Wednesday 29 January 2014

Rainy Night Ahead, Showers Lingering into Thursday JANUARY 29, 2014


Rainy Night Ahead, Showers Lingering into Thursday

JANUARY 29, 2014

It’s been a cloudy, wet day across portions of northern California today outside of the delta area and the west side of the Sacramento valley where some rain shadowing has taken hold. Outside of those areas, the east side of the valley, portions of the coast, coastal mountains, west slope of the sierra (& sierra itself of course), and the foothills have nearly all seen measurable precipitation from around north of Jackson. Personally, here in Rocklin (Placer county), I’ve picked up .14″ thus far ahead of the main precipitation band.

Offshore as of 7:30pm, an upper low about 700 miles offshore from the coast of northern California is pulling up a long fetch of sub-tropically based moisture, with the tropical convective source blooming over Hawaii. This sub-tropical moisture plume-infused 100 – 130kt jet streak has been blasting northern California/Oregon today, and is what is assisting in the intensifying offshore precipitation band associated with the upper low and it’s cold front.


Given precipitable water values of 1.2 – 1.3″ and rather strong 700mb vertical velocities indicative of strong vertical motion (lift) along and ahead of the cold front along the frontal precipitation band, moderate to heavy precipitation seems in order once the system begins pushing ashore. Nose of the precipitation was just beginning to make it inland as of 7:35pm, and thus expecting precipitation to become widespread again after 8:30 – 9pm tonight (Thursday). Frontal precipitation will continue through around 2 – 3am in the Chico area, cutting off around 3 – 5am in the Sacramento area.
1z HRRR indicating moderate to perhaps heavy precipitation ahead of cold front late tonight into the early morning hours of Thursday.

Given 850mb temps ahead of the front remaining above 4c or so through 12 – 2am, snow levels will remain above 6000ft through at least 1 – 2am. After around 2am, I’m more confident that snow levels will dip down to around 4000ft by 4 – 5am. While the front will slide through the South Lake Tahoe area around 3 – 5am, moist upslope flow will continue through morning Thursday continuing precipitation development up the west slope of the sierra to the sierra crest.

Snow increasing in areal coverage (blue) through the overnight and morning hours of Thursday.

Total QPF amounts still look to be around .25 – .75″ in the valley, with 1 – 3.5″ in the mountains, with the heaviest amounts along southwest facing slopes. This translates to about 1 – 2ft of snow above 7000 – 7500ft, with 6 – 12″ above 5000ft, and a few inches down to 4000 – 4500ft.


Convection:

Models have pushed back the timing of the upper low itself to slide across northern California to the late afternoon during the evening hours, which won’t be very favorable for strong convection due to the best source of lift being that low, and with it offshore it wouldn't be close enough to northern California to produce the lift we need. Despite this, it appears this may be a good setup to see some pockets of clearing by mid to late morning Thursday behind the overnight front and the upper low. With -20 to -25c 500mb temperatures aloft within the trough diving overhead Thursday and surface temperatures warming upper 50s and locally low 60s in the valley with 30s and 40s in the mountains, low-level lapse rates should rise on up into the 6 – 8c range, with a plume of moderately steep mid-level lapse rates also sliding overhead Thursday afternoon as the trough’s base places itself over northern California.


Given the upper low is now forecast to remain offshore until late Thursday, shear will remain rather weak through the day Thursday. Despite that, surface based CAPE values are forecast in the 200 – 500 j/kg range in the foothills, and mountains north of Highway 50 Thursday afternoon. The RAP even indicates some MLCAPEs of 300 – 500j/kg from Placer to Butte county, which is pretty decent for northern California given we typically with with low instability setups in the winter months. While lift won’t be too significant, upslope flow and more upper level lift is forecast to be present Thursday afternoon within the base of the trough, mountain convective initiation seems most likely Thursday afternoon, with storm motions being for the most part from north to south.
0z 4km NAM’s forecast mixed-layer CAPE valid for mid-afternoon Thursday, indicating rather decent values in the west slope of the sierra and north-central mother-load foothills.

There is a slight chance the low could move a bit faster than forecast and support some convective development in the valley, but the “slight chance” is key. Certainly not a given in this case. The best chance in the foothills would be from Sonora south, given the jet will be further south associated with the front in southern California during the day Thursday.
0z 4km NAM’s forecast reflectivity valid for the later afternoon Thursday, indicating some convection over the northern sierra.

Thunderstorms in the mountains would be capable of hail, very heavy rain or snow depending on elevation/location, and gusty winds given undirectional shear profiles.

Things clear out through the day Friday, and should remain dry across most of northern California through at least the middle of next week, at least based on current models. One additional low within the trough is expected to slide down the coast Sunday into Monday, if current models are correct with the track, all precipitation may remain offshore with the system, despite perhaps some showers in the northern mountains.

As while this system will bring us some much-needed precipitation, this won’t be nearly enough to even nudge the current severe drought we’re stuck in, it would take another 15 or so of these systems to effectively put a hamper on our current drought, and it doesn’t look like we’ll have a train of storms of that magnitude in the near future.

Whenever a new system arises, I’ll post an update. Some indications that a trough could get in here late next week, but there’s considerable disagreement at the moment.

Post your rainfall totals in the comments or on the Facebook page if you like!

Tuesday 28 January 2014

Wednesday/Thursday Storm Update: Rain, Snow, & Thunderstorms

Wednesday/Thursday Storm Update: Rain, Snow, & Thunderstorms

Posted January 28, 2014 by wxtracker15 & filed under Active, Convection, Storm,Thunderstorms, Trough, Winter.



After weeks upon weeks of unseasonably dry and warm weather across the state, over the last few days a decent sized system has been taking shape in the east-central Pacific, north of Hawaii. This system consists of a couple of upper lows spiraling around north of the fierce 100 – 130kt jet within the trough, and a large plume of sub-tropical moisture steaming on up from the Hawaiian islands area.


Over the last couple of days this stream of moisture has been hosing Oregon and far northern California with some light to moderate rain, which itself isn’t very significant, but the depth and amount of moisture present is notable, with precipitable water values in excess of 1″, and may reach values of around 1.3″ Wednesday ahead of the main cold front involved with this system.

As the upper low(s) begin their eastward track Wednesday, a tightening in thermal/temperature gradients develops in the eastern Pacific, a new low is modeled to develop and strengthen lift to the east of the low, stretching east into northern California along a stationary/warm front. Along this boundary is where precipitation will begin to develop and fill in through the day Wednesday. Precipitation will likely fist start along the coast as the stream of moisture begins to drop south out of southern Oregon, then in the mountains as orographics strengthen. Still some uncertainty as to when precipitation may begin to fill in-in the valley, but generally models indicate low-level saturation and strengthening in lift enough for precipitation development in the lower elevations by mid to late afternoon, perhaps as early as early afternoon in some locations and as late as early evening in other locations. In the San Joaquin valley, precipitation may not begin until mid to late evening due to the front not speeding up it’s southward run until around that time.

00z 4km NAM’s forecast reflectivity valid for the later evening Thursday.

As the system strengthens just offshore Wednesday evening, frontal and pre-frontal lift also increases in intensity across northern California through the evening Wednesday, also increasing precipitation intensity. Given 1.2 – 1.3″ PW values and 700mb vertical velocities of 40 – 50 UB/s in the valley and 700mb VV’s in the 50 – 90 UB/s range in the foothills and mountains ahead of the cold front Wednesday night into early Thursday morning, moderate to heavy precipitation seems quite likely up until frontal passage Thursday morning.

4km NAM’s forecast 700mb vertical velocity and 700mb heights valid for mid-evening Wednesday.

Snow levels are forecast to start out rather high given the warm origins of the system’s moisture tap, likely starting out up around 7500 – 8500ft in most sierra locations. Through the night Wednesday into Thursday morning, snow levels steadily drop off to perhaps around 4000 – 5000ft Thursday. Even after frontal passage Thursday morning, upslope flow and orographic effects will continue to support precipitation development over the higher elevations.

4km NAM’s forecast precipitation type valid during Wednesday morning, indicating little snow in the sierra due to high snow levels.

4km NAM’s forecast precipitation type for early Thursday morning as the initial cold front passes. Snow level drops off a few thousand feet compared to the evening Wednesday.

Will the valley dry out after the first front passes early Thursday morning you ask? Well, it appears it may not – in fact, it could be quite the contrary. High resolution models are indicating that a secondary front may develop in the colder air behind the sub-tropically infused first cold front, and slide through northern California later Thursday morning into the mid or even late-afternoon, just in time for peak heating.

00z NAM’s forecast reflectivity valid early Thursday afternoon, indicating another round of precipitation moving inland with a shortwave.

This second front/precipitation band appears to be associated with the main shortwave that drove in the initial cold front, which may energize cloud tops enough with the second band to support some convection along the second band. If the valley were to see any cloud breaks Thursday morning before things cloud back over ahead of the secondary system, instability could be enough to assist in the development of some thunderstorms Thursday afternoon into the early evening in the valley and foothills… perhaps even along the coast if the shortwave is strong enough.

Even with limited sunshine, high resolution models are generating surface based CAPEs of 100 – 300 j/kg, with more bullish solutions, such as that of the 4km NAM’s, indicate values of around 500 j/kg along a band from Yuba City to Modesto. In addition to a bit of CAPE, lifted indexes (LI) are also forecast to dip to around 0 to -3c depending just how unstable the valley is able to get. Now, if I’m talking convection here, I just have to dab into the shear aspect of this setup (then again, who wouldn’t?). Taking a peak at the NAM’s hodographs, I can find my favorite shape present in most Sacramento valley site forecast hodo’s, and that’s a clockwise curve. What does this clockwise curve mean you ask? Well, it indicates that there is some decent turning going on with height wind wise, which as some of you may know is great for developing rotating updrafts in thunderstorms, and thus, supercell structured storms. To support these hodographs indications, 0 – 3km storm relative helicity values are progged in the 100 – 200 M2/S2 range, which is well within the range of which mini-supercells are known to have occurred/developed in. The only iffy thing about this event is coverage of showers/storms Thursday, and when the second front exits the valley.

4km NAM’s forecast surface based CAPE valid for later Thursday afternoon, indicating 250 – 500 j/kg values in the southern Sacramento/northern SJ valley.



NAM’s forecast hodograph for Thursday afternoon.

If the front exits the valley by or before around 1 – 3pm, there would be a few hours left of sunshine in the valley to increase instability and lapse rates, perhaps enough to get storms developing and possibly rotating if instability were to be strong enough. Another, well, option per-say would be for there to be some sunshine ahead of the second front, which is also possible, but not set in stone, as there could be lingering status over the region. In either of these solutions thunderstorms would be possible, either along/within the secondary precipitation band, or behind it if there is enough time left before sunset.

In the case thunderstorms do develop, as mentioned before, there is enough directional shear for some rotating thunderstorms/supercellular structures. And if storms of such strength were to develop, they could become capable of hail, gusty winds, and weak tornadoes. Again, that’s if there is enough instability and shear for mini-supercells to develop and sustain themselves, which is possible, but not set in stone.

Once the trough’s base shifts east, lift ceases to exist and precipitation also ceases to exist through the night Thursday. Throughout this ~48 hour event, .25 – .50″ of rain appears possible for a good chunk of the Sacramento and northern San Joaquin valley, with amounts up to an inch possible along the east side of the valley, where uplsoping/precipitation banking along the foothills and western slope stack up and intensity precip from the east side of the valley up into the foothills and western slope of the sierra. Along south and southwest facing slopes, where orographics are maximized from this system, 3 – 5″ of precipitation appears possible, with 2 – 3″ possible in most of the west slope as well. .75 – 2″ also appears likely in the coastal mountains, with 2 – 5″ along the northwestern corner of the state. It appears the west side of the valley could be moderately to severely rain-shadowed, limiting precipitation quite a bit compared to areas that aren’t directly adjacent to mountain ranges.

Snow wise, currently looks like around 8 – 10″ is possible around 4500ft, with 1 – 2ft above 6000ft. These amounts will likely be enough to cause some travel issues across the sierra Wednesday night and Thursday, and while winds won’t be all that significant, snowfall intensity at times could be heavy enough to limit visibility quite a bit, adding to the travel danger of driving on snow.

Things are forecast to remain dry through the weekend into at least early next week as a ridge takes over once again, but we won’t be climbing into the 70s any time soon, as we’ll be stuck under some much colder air draining southward from Canada.

If anything changes forecast/model wise Wednesday, especially regarding the threat of convection Thursday, I’ll be sure to update this post or post an entirely new post if needed. Stay tuned, and be sure to check out the site’s Facebook page (can be found to the right) for “nowcasts” and up to the minute updates on active weather.

Interactive NWS Alert Information New Event for Delaware County


Interactive NWS Alert Information
New Event for Delaware County
SPS valid from Jan 28 6:28 PM to Jan 29 5:00 AM EST
Sent to SMS and E-Mail at Jan 28 6:28 PM EST

Radar Time: Jan 28 2014 8:55 PM EST
000 WWUS81 KPHI 282328 SPSPHI SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 628 PM EST TUE JAN 28 2014 DEZ001-MDZ008-NJZ010-012>019-PAZ070-071-102-104-106-291000- NEW CASTLE-CECIL-SOMERSET-MIDDLESEX-WESTERN MONMOUTH- EASTERN MONMOUTH-MERCER-SALEM-GLOUCESTER-CAMDEN- NORTHWESTERN BURLINGTON-DELAWARE-PHILADELPHIA-EASTERN CHESTER- EASTERN MONTGOMERY-LOWER BUCKS- INCLUDING THE CITIES OF...WILMINGTON...ELKTON...SOMERVILLE... NEW BRUNSWICK...FREEHOLD...SANDY HOOK...TRENTON...PENNSVILLE... GLASSBORO...CAMDEN...CHERRY HILL...MOORESTOWN...MOUNT HOLLY... MEDIA...PHILADELPHIA...WEST CHESTER...KENNET SQUARE... NORRISTOWN...LANSDALE...MORRISVILLE...DOYLESTOWN 628 PM EST TUE JAN 28 2014 ...A PERIOD OF ACCUMULATING SNOW LATER TONIGHT... SNOW IS EXPECTED TO OVERSPREAD THE AREA LATER THIS EVENING AND FALL AT ITS GREATEST INTENSITY AROUND MIDNIGHT. THE SNOW WILL END BEFORE THE START OF THE MORNING COMMUTE ON WEDNESDAY. ACCUMULATIONS SHOULD AVERAGE CLOSE TO ONE INCH, WITH SOME HIGHER AMOUNTS POSSIBLE EAST OF THE TURNPIKE IN NEW JERSEY AND SOUTH OF INTERSTATE 95 IN DELMARVA. THE LATEST MESOSCALE MODELS ARE SHOWING THAT THIS AREA IS GOING TO BE CLOSE TO THE PIVOT POINT AS TO HOW FAR WEST THE ACCUMULATING SNOW WILL BE ABLE TO REACH. THE SNOW WILL STICK INSTANTLY ON UNTREATED ROADWAYS AND MAKE FOR SLIPPERY TRAVEL. IF DRIVING OVERNIGHT, GIVE YOURSELF SOME EXTRA TIME TO REACH YOUR DESTINATION. ALSO GIVE YOURSELF SOME EXTRA TIME FOR THE MORNING COMMUTE ON WEDNESDAY, ESPECIALLY IF YOU ARE DRIVING EARLY OR HAVE COMMUTING PLANS TOWARD THE SOUTHEAST. 
GIGI/GORSE

Sunday 26 January 2014

Wet Weather by Mid-Week, Though no Drought Buster



Wet Weather by Mid-Week, Though no Drought Buster 

After a very long period of dry weather with weak storms here and there, models have locked onto a system developing in the east-central Pacific this week, kicking east off the western U.S. coast by mid-week and offshore by late-week, which should bring some more widespread precipitation to at least the northern half of the state between mid and late-week.
Currently, a cutoff low is spiraling around off the southern California coast, one of a few that have either come up from the southeastern Pacific, or east from the Great Basin. To the west of that, a large deep low about 1000 miles off the WA/OR coast is forecast to ride over the ridge sitting over the western U.S. coast, sending it into Alaska Monday.
It appears as though the tail end of the large system off the western U.S. coast may bring northern California some light precipitation late Monday into early Tuesday, and while it wouldn’t be significant, this system will open door for the next.

A piece of energy rotating around this strong, deep low in the Gulf of Alaska will dive north of Hawaii Tuesday, tapping into a plume of sub-tropical moisture. When this occurs, a tighter thermal gradient develops, and allows the system to strengthen into a more large scale trough/upper low, pushing eastward Wednesday.
12z GFS’s 300mb wind and heights valid for Wednesday morning, indicating the base of the trough off the western U.S. coast by about 1000 miles, directing strong jet stream level winds into California, Oregon, and Washington. You can also point out how far south the jet extends, where it;s likely tapping into some sub-tropical convection east of Hawaii.

It appears this sub-tropical moisture plume and band of frontal lift will begin to nose into northern California as early as Wednesday, increasing clouds and beginning the onset of precipitation across the region through the day. Precipitation is currently forecast to continue into at least Thursday before the base of the trough moves its way inland, sending the back edge of the cold front through and cutting off lift, and precipitation with that. Colder air aloft within the trough may promote some instability during the day Friday behind the front, so some convection isn’t out of the question, depending on placement of the upper-level low.

Precipitation is currently modeled to be more or less light to moderate through most of the event, however given 1.1 – 1.3″ precipitable water values it doesn’t take much variation in the strength of the upper low to affect precipitation intensity and amounts. I should know more by the next update I post on this system Tuesday.
Snow levels with this system are forecast to begin rather high due to the tropical origin of the moisture, likely around 6000 – 7000ft, but should lower to around 4000ft by Thursday as colder air behind the cold front works its way overhead.

Current model guidance indicates .25 – .75″ of rain in the valley, however models have had issues with the strength of the system and how long it sticks around, with some model runs and ensemble members dumping over an inch of rain in the valley, which does seem plausible given the significance of the sub-tropical moisture plume… but for now we can wait a couple more days for more precise/higher resolution model guidance and run to run confidence. 1 – 3″ is the mean of model indications in the foothills and mountains, with locally upwards of 4 to 5″ in orographically enhanced areas, but there could be even more if wetter solutions were to vertify.
Several GFS ensemble members’ (not all are shown) 72 hour precipitation for the Wednesday – Friday trough/precipitation. event. The members that produce the most precipitation indicate more purple, which indicates 1.5″+.

Right now, it appears we’ll remain under the cold trough into the weekend, but unsure if any additional shortwaves within the trough will bring us any additional precipitation at this time. For now, main concentration is on the Wednesday – Friday system, and I plan to have another update by Tuesday as aforementioned, when high-res models are in range, and more is known about what the weekend, and possibly even what early next week has in store.

Even if the wettest models were to be correct, it certainly won’t be enough to produce any significant drought relieve, but of course any bit we can get will help at least somewhat, but we need an exceptional amount of precipitation from here on out through our known wet season (which continues into April, and some years lingers into May/early June) to get us out of these severe drought conditions.
Precipitation required to end a drought based on a -2 PHDI through the next 3 months. This was based on conditions through December, though, and given we’re in later January and the same pattern has stuck, we may be in a more widespread -3 PHDI now, requiring even more precipitation.


Stay tuned for the next update on this system.

Friday 17 January 2014


UPDATED: Driest Year Ever in California, Drought Officially Declared

Posted on January 16, 2014

2013 was California’s driest year since 1849, when the state started measuring rainfall. Low rainfall measurements broke prior records in Los Angeles, San Francisco, Shasta and up to Eugene, OR. Experts say that if rain doesn’t fall soon, the worst may be yet to come.







“The 2013–14 water year is off to a rotten start,” the University Corporation for Atmospheric Research (UCAR) wrote in their analysis. As of January 10th the Sierra snow pack, which is responsible for about a third of California’s water, was at 84% below average.





The high pressure zone, winter 2012-2013 to now – Credit: NOAA/ESRL


Meteorologist say the cause for this dry spell is a massive high pressure zone, about 4 miles high and 2,000 miles long, that’s been blocking storms for more than a year. This zone typically comes and goes year to year — but this year, it stayed put and the consequences can be dire.




Another view of the high pressure zone – Credit:WeatherWest.com


Some of the potential consequences California faces: 
Combine this dryness with the Santa Ana winds, the risk of huge wildfires grow exponentially! 
Impact on agriculture and food cost, and the jobs in this sector 
Impact to water and energy bills 
Impact to fresh water recreation, such as fishing, swimming and boating 
Water supply shortage for rural residents — can creep to cities if it gets bad enough 
Water-use restrictions — less showers, car washes, etc. 




2013 was the driest year on record for most of California – Credit: WRCC/DRI


California’s Governor Jerry Brown will officially declare a drought soon. Let’s hope it starts raining soon!


Wednesday 15 January 2014

Early Season Fire Danger & Strong Valley Inversion This Week

Think it's warm in the valley? Some locations in the foothills and western slope of the sierra are upwards of 10 degrees warmer due to the strong inversion that is trapped over the Sacramento and San Joaquin Valley.


With no precipitation in the forecast throughout northern California for at least the next week or so, there is no drought drought relief in sight. This historically dry streak over the last year has lead up to this: an early season fire weather event expected to linger through the week this week.

Never would have thought I’d be making maps having to do with fire danger in the middle of January.

Offshore winds across California are, and really already have dried out the low-levels significantly, and in addition to the very dry low-levels, the offshore wind gradient is strong enough to support some locally gusty winds throughout northern, central, and southern California.

In this graphic I’ve plotted dew points in the fill and dew point values from METAR sites across the region. The lower the dew point, the dryer the air.

What’s causing this offshore flow you ask? The core of our exceptionally strong ridge is sitting off the northern California/Oregon coast, directing some upper level winds to spiral clockwise around it, which sends northeast to easterly winds right over California. The ridge center will slowly work its way overhead Thursday and Friday, allowing winds to weaken… though, could remain locally breezy. Dew points and humidities will have a hard time recovering through the rest of the week into the weekend due to the offshore flow continuing, though weakly.

300mb heights and winds plotted through the 4km NAM indicating the clockwise flow of the super-ridge off the CA/OR coast.

In addition to dry and breezy conditions, a strong to very strong inversion has set up over the Sacramento and San Joaquin valley, where winds aren’t strong enough to mix out this warm belt a couple thousand feet above the surface. This is keeping the valley about 5 – 10 degrees cooler than most foothill and western slope locations. Generally valley temperatures have remained in the mid to locally upper 60s (except in the north valley where the inversion isn’t present, allowing them to reach the low, mid, and even locally upper 70s), while foothills and mountain communities between 1000 and 4000 – 5000ft in elevation are warming into the low to mid 70s. Overnight lows in the valley have been quite cool due to the trapped cooler air, dipping into the 30s, while in the foothills and mountains where the inversion layer is present, most lows have been in the upper 30s to mid and even upper 40s locally.


In this graphic I plotted surface (well, 2-meter) temperatures in the fill and surface temps via METAR sites. Compare temperatures from the Sacramento/San Joaquin valley to those in outlying mountain areas.

This pattern with elevated fire danger and strong inversion temperature gradients is expected to continue into the weekend, then an odd split-flow and possibly a cutoff low are expected to develop by next week, perhaps breaking up the inversion and bringing cooler temperatures and perhaps some clouds. Models are all over the place with the cutoff low portion of the forecast, with some runs dropping it and others continuing to indicate it. For instance, the ECMWF has indicated some sort of closed low for the last few days, while the GFS has been flipping and flopping… but seems to have trended way from that idea for now. The GEM also dropped the idea of a cutoff low and instead keeps our exceptionally strong ridge overhead, and in fact strengthens and amplifies it further.

I’ll keep an eye on next weeks pattern for anything interesting and have an update when confidence is high in whatever evolves out of next weeks pattern, whether it winds up being dry or perhaps a bit wet (which right now seems unlikely).




Wednesday 8 January 2014


Sunspot goes wild! 

X-class solar flare blasts in our direction
Image: Solar activity
A false-color composite image from NASA's Solar Dynamics Observatory shows a blast of activity originating from an active sunspot region at the center of the sun's disk on Tuesday.



The sun erupted with a powerful solar flare on Tuesday, disrupting radio traffic and sending a blast of electrically charged particles our way. And there may be more blasts to come.

The X1.2-class flare was recorded by sun-observing satellites, including NASA's Solar Dynamics Observatory, at about 2:32 p.m. ET. X-class flares are the strongest category of solar outbursts, although X1.2 is toward the category's low end. The National Oceanic and Atmospheric Administration's Space Weather Prediction Center said the flare sparked a strong radio blackout.

For days, space weather forecasters have been bracing themselves for solar eruptions from a large active sunspot region called AR1944. This region has now turned to face Earth directly, which means strong solar flares are likely to send storms of charged particles — also known as coronal mass ejections, or CMEs — heading straight for us.

Strong solar storms can damage satellites and electrical grids. One such outburst in 1989 knocked out power for a wide swath of Quebec. And don't get us started about thesuperstorm of 1859!

The geomagnetic storm generated by Tuesday's flare won't be that disruptive, but it could have an impact. NASA expects the CME to sweep over us somewhere around 3 p.m. ET Wednesday. The current space weather report says there's a chance we'll see more X-class flares through Friday.

Although space storms can be damaging, they can be beautiful as well: Be on the watch for enhanced northern lights over the next couple of nights. To get the auroral forecast for your area, check out the maps at SpaceWeatherLive.com. And for cool views of the aurora, keep an eye on SpaceWeather.com.

Update for 9:30 a.m. ET: Tuesday's massive solar flare has forced the commercial spaceflight company Orbital Sciences to postpone the planned launch of a private cargo mission to the International Space Station today. Read the full story here: Huge Solar Flare Delays Private Rocket Launch to Space Station

A massive solar flare erupted from the sun on Tuesday (Jan. 7), rising up from what appears to be one of the largest sunspot groups seen on the star's surface in a decade, NASA officials say.

NASA's Solar Dynamics Observatory captured a video of the huge solar flare as it developed, showing it as an intense burst of radiation from a colossal sunspot region known as AR1944. The sunspot group — which is currently in the middle of the sun as viewed from Earth — is "one of the largest sunspots seen in the last 10 years," NASA officials wrote in a statement. It is as wide as seven Earths, they added.

Tuesday's big flare was an X1.2-class solar event on the scale used to classify sun storms. It occurred at 1:32 p.m. EST (1832 GMT) and came just hours after an M7.2-class flare. Space weather officials at the the Space Weather Prediction Center overseen by NOAA are expecting the flare to spark geomagnetic storms in Earth's magnetic field when a wave of super-hot solar plasma associated with the flare - known as a coronal mass ejection - reaches Earth in the next few days. [Photos: The Biggest Solar Flares of 2014]

"This is the first significant flare of 2014, and follows on the heels of mid-level flare earlier in the day," NASA spokeswoman Karen Fox of the agency's Goddard Space Flight Center in Greenbelt, Md., wrote in a statement. "Each flare was centered over a different area of a large sunspot group currently situated at the center of the sun, about half way through its 14-day journey across the front of the disk along with the rotation of the sun."

X-class solar flares are the most powerful solar storms on the sun. Mid-level storms are dubbed M-class events and can supercharge Earth's northern lights displays, with weaker C-class flares rounding out the top three.
This labeled image taken by SDO's Helioseismic and Magnetic Imager shows the location of two act …

When aimed directly at Earth, the strongest X-class solar flares can pose a risk to astronauts in orbit and interrupt communications and navigation satellite operations. 

Tuesday's solar flare did force the commercial spaceflight company Orbital Sciences to delay the launch of its first Cygnus cargo mission to the International Space Station from NASA's Wallops Flight Facility on Wallops Island, Va.

NASA officials told SPACE.com today that the crew of the International Space Station will not have to take measures to shelter themselves from the solar flare's radiation effects. There are currently six astronauts living on the station as part of the outpost's Expedition 38 crew. The team includes three Russian cosmonauts, two NASA astronauts and one Japanese astronaut.

The sun is currently in an active phase of its 11-year solar cycle. The current cycle, called Solar Cycle 24, began in 2008. 


Tuesday 7 January 2014

'Polar Vortex' 
Creates Huge Temperature Difference Across US

A blast of Arctic air pushing south as far as Atlanta has caused air temperatures across the United States to plunge, creating a massive 140-degree Fahrenheit (77 degrees Celsius) temperature difference between the chilly Dakotas and balmy Florida yesterday (Jan. 5).

The pulse of frigid air, called a polar vortex, whirled into the United States this weekend on the heels of a majorwinter storm. But unlike that storm, the polar vortex won't bring heavy snowfall. (The snowstorm dropped nearly 2 feet, or 60 centimeters, of snow in Boston last week.) Instead, the National Weather Service is forecasting dangerous cold and windchills. The cold temperatures are expected to last through Wednesday, the NWS forecasts.

The polar vortex is a low-pressure system that circulates from west to east in the Arctic during winter. Late last week, a high-pressure system — called an atmospheric block — situated over northeastern Canada and Greenland stopped this circulation pattern, pushing the cold air into the United States. On Sunday afternoon, temperatures ranged from minus 55 F to 85 F (minus 48 C to 29 C), according to NWS weather data.

On Monday morning, air temperatures in North Dakota and South Florida were still more than 100 F apart. Chicago set a new record low of minus 16 F (minus 27 C) Monday morning, and Tulsa, Okla., broke a 102-year record with a new low of minus 1 F (minus 18 C) recorded at 7:14 a.m. local time, the NWS said.



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Sunday 5 January 2014

Winter Storm Ion Forecast: Heavy Midwest Snow, Freezing Rain for South and East, Then Widespread Brutal Cold


Winter Storm Ion Bringing More Snow
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Winter Storm Ion Bringing More Snow 
Life Threatening Cold 



Winter Storm Ion is spreading a swath of heavy snow across the Midwest, and its icy tentacles will also bring wintry weather into the South and parts of the East. Following closely behind Ion will be a blast of brutally cold air.


What can you expect from the snowy side of Ion? We have the forecast details below.
Snow, Wintry Mix From Midwest into Deep South
Current Radar


Snowfall Forecast

Sunday Night South Forecast


The primary low pressure center associated with Winter Storm Ion will continue to intensify as it tracks northeast Sunday night. The low should be near Toronto by 3 a.m. Monday.

This track has lead to widespread accumulating snow from Missouri to Illinois, Indiana, Ohio and southern Lower Michigan. The National Weather Service placedwinter storm warnings into effect for large portions of these states, valid through Sunday evening and the wee hours of Monday morning. Additionally, a blizzard warning has been issued through the overnight hours for parts of north-central Indiana and far southwestern Michigan. 

The snow will wind down from southwest to northeast Sunday night. Most areas west of Interstate 65 should be done with the snow by midnight Sunday night. Although, by 10 p.m. Sunday, snow totals had already exceeded 12 inches in parts of Missouri, Indiana, and Illinois.


In parts of Kentucky, Tennessee, West Virginia, western Pennsylvania and Ohio, there will be a period of rain changing over to snow as the arctic cold front charges east Sunday night. Snowfall amounts will be lighter in these areas owing to the shorter duration of the snow.


The changeover from rain to snow or a mix of sleet and freezing rain has reached into the Deep South as well, starting in north Mississippi late Sunday afternoon, it will then briefly swept into north Alabama Sunday evening,. Sunday overnight, the changeover to snow will move into north Georgia after midnight. Although snow and ice accumulations will be light, slick travel conditions are likely, especially on bridges and overpasses, given that the arriving blast of sharply colder air will likely freeze any moisture on the roads. Icy patches could remain a problem through Tuesday night as temperatures stay well below freezing all day Monday and Tuesday in these normally mild locales.

Additional lake-effect snow in the wake of Winter Storm Ion will add to the totals over west and southwest Michigan and parts of far northern Indiana, boosting storm totals past the one-foot mark. Lake-effect snows will also kick in for northeast Ohio Monday through Wednesday with significant amounts possible.

Ion is also impacting the Northeast, but with a different outcome from what we just saw with Winter Storm Hercules.
Ion Slides Through the Northeast
Sunday Night Forecast

Monday's Forecast


Since the area of low pressure associated with Ion will track inland across the Ohio Valley into Ontario through Sunday night, we are not expecting much snow in the Northeast.

(FORECAST: Boston | New York | Washington)

Unfortunately, the recent cold air mass is dense and stubborn and is not easily scoured out by the southerly winds ahead of Winter Storm Ion. As a result, freezing rain remains a concern from northern Virginia northward into upstate New York and New England.

The highest ice totals are expected to be in a small area from northwest Virginia through north-central Maryland into parts of south-central Pennsylvania. Here, 1/4 inch of ice glaze may be enough to snap some tree limbs and cause spotty power outages before temperatures rise above freezing Sunday night. Untreated pavement will be very slick in affected areas, so walk and drive with caution.

Farther north over interior New England, the wintry mix of sleet and freezing rain Sunday evening should gradually change over to rain from south to north through the night. Northernmost areas of New England, however, may remain icy all night.

Bitterly cold wind flow around the departing low pressure system will also allow lake-effect snow to develop east of Lakes Erie and Ontario Monday through Wednesday, affecting areas from Erie, Pa. to Buffalo, N.Y., and between Syracuse and Watertown, N.Y. Snow accumulations will likely exceed 2 feet east of Lake Erie and well over 3 feet east of Lake Ontario, causing travel to become nearly impossible on the usual stretches of I-90 and I-81, respectively. Closures are likely due to the combination of heavy snow and extremely dangerous wind chills.

MORE ON WEATHER.COM: Photos of Winter Storm Ion



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The Chicago skyline and a freezing Lake Michigan are seen from the Museum Campus in Chicago on Sunday, Jan. 5, 2014. (AP Photo/Nam Y. Huh)

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