About Jeff Masters
Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
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California Drought Worsening During Height of Rainy Season
By: Dr. Jeff Masters , 9:10 PM GMT on January 23, 2015
The Western U.S. winter rainy season has reached its halfway point, and there is only bad news to report for drought-beleaguered California. November through March marks the period when California receives its heaviest rains and snows, thanks to the wintertime path of the jet stream, which dips to the south and brings wet Pacific low pressure systems to the state. The rainy season started out promisingly, with several December storms bringing precipitation amounts close to average for the month over much of the state. Troublingly, though, record-warm ocean temperatures off of the coast meant that the December storms were unusually warm. This resulted in snow falling only at very high elevations, keeping the critical Sierra snow pack much lower than usual. The jet stream pattern shifted during January 2015, bringing disastrously dry conditions to the state. January usually brings 4.19" of rain to San Francisco, but no rain at all has fallen in January 2015 in the city--or over much of Central California. The dryness has been accompanied by near-record warmth at higher elevations in the Sierras, with temperatures at Blue Canyon and South Lake Tahoe averaging nearly 8°F above average for the month of January. As a result, the snowpack in the Sierras--a critical reservoir of water that is used throughout the rest of the year--is abysmally low, running about 30% of normal for this time of year. California's eight largest reservoirs are 33% - 86% below their historical average, and the portion of the state covered by the highest level of drought expanded in mid-January--a very ominous occurrence for the height of the rainy season. 
Figure 1. The Enterprise Bridge passes over a section of Lake Oroville that was nearly dry on September 30, 2014, in Oroville, California. Lake Oroville, California's 2nd largest reservoir, was at 49% of average (30% of capacity), the second lowest level on record (behind 1977.) Heavy rains in December 2014 allowed lake levels to recover slightly--as of January 23, 2015 Lake Oroville was at its 7th lowest level of the past 35 years. Image credit: California Department of Water Resources.
Figure 2. The same view of Lake Oroville in happier times: July 20, 2011. (Paul Hames/California Department of Water Resources/Getty Images)
The forecast: hot and dry
An intense ridge of high pressure will build in over California this weekend, bringing near-record high temperatures in the low to mid-70s to San Francisco. The all-time hottest January temperature in San Francisco of 73°F, set just last year, could fall on Sunday. The ridge of high pressure will stay entrenched over California during the remainder of January, bringing continued dry conditions. A weak upper-level low pressure system will bring a few rain showers to the state beginning this Tuesday, but rainfall amounts will be generally less than 1/2"--an insignificant drop in a very large, dry bucket. With long-range models showing no shift in the jet stream pattern through the first week of February, California may be on its way to a fourth consecutive bone-dry rainy season--pushing the state into an increasingly dire drought situation.
Figure 3. Time series of the change in drought conditions in California from January 28, 2014 through January 22, 2015. The area covered by the worst category of drought--"Exceptional"--peaked at 58% during the summer of 2014. In December 2014, "Exceptional" drought coverage fell to 32%, thanks to heavy rains, but this area increased again to 39% in mid-January 2015 due to unusual dryness. Image credit: drought.gov.
Related blog post: The State of the California Drought: Still Very Bad, January 13, 2015, by water resources expert Dr. Peter Gleick of the Pacific Institute.
Jeff Masters
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605. win1gamegiantsplease
5:57 PM GMT on January 28, 2015604. tiggerhurricanes2001
11:02 PM GMT on January 26, 2015603. vis0
10:51 PM GMT on January 25, 2015Now i have to spend 3 times longer on the phone explaining to my relatives in Puerto Rico, that i'm not asking them if they know?! Juno?
If its been said too bad, i just woke up and filling my calories to get ready for a long hard walk across Manhattan during the storm, gonna wifi the storm abroad LIVE lets see if wx conditions allow it.
602. CraigsIsland
8:43 PM GMT on January 25, 2015That is absolutely crazy
601. BahaHurican
8:06 PM GMT on January 25, 2015600. Climate175
7:17 PM GMT on January 25, 2015599. georgevandenberghe
7:07 PM GMT on January 25, 2015This was huge for total snow over a large area, severe weather over FL and Cuba, storm surge over FL, Snow into the FL panhandle, huge snow totals deep into the southeast and near record single storm accumulations over the Piedmont from Georgia to Maine. It was not huge for snow along the I95 corridor, every major metro got about a foot followed by dry slotting rather than the forecast 2-3 feet with no dry slotting. This error was due to 12H earlier than forecast development of the storm resulting in a more westward track, and a shift of the warm air a little (50 miles) further west which also placed the dry slot along the metro corridor rather than just offshore. West of that dry slot in Central Va and the foothills of the Appalachians, they got what we were fearing, 2-3 feet of snow.
598. hurricanes2018
6:33 PM GMT on January 25, 2015597. Hazardousweather
6:33 PM GMT on January 25, 2015What's the biggest one so far this century?
596. stormchaser19
6:31 PM GMT on January 25, 2015595. WunderAlertBot (Admin)
6:30 PM GMT on January 25, 2015594. VermontStorms
6:28 PM GMT on January 25, 2015Thank you, in my memory it seemed that the criteria included total snowfall, high winds and very very cold. I am not sure how to measure snowfall in high winds, though.
593. VermontStorms
6:26 PM GMT on January 25, 2015I must say, I like your map better than the current NWS forecast for my area, but while you are at it, could you move that 30" forecast into Vermont? (You may note that when snow is involved I always count on the highest end of the forecast as a promise)
592. Drakoen
6:25 PM GMT on January 25, 2015Will be a great storm to watch for sure. Convective snow bands running over the same areas for a long period of time. Dangerous situation.
591. georgevandenberghe
6:24 PM GMT on January 25, 2015Veterans day Snowstorm 1987. Forecast flurries, verification 18" in Central and South PG County.
590. wxgeek723
6:24 PM GMT on January 25, 2015First it was Nemo
Then it was Hercules
Now it's Juno
589. hurricanes2018
6:23 PM GMT on January 25, 2015588. sar2401
6:20 PM GMT on January 25, 2015587. georgevandenberghe
6:19 PM GMT on January 25, 2015Terminal C or terminal B??
586. washingtonian115
6:19 PM GMT on January 25, 2015Link
585. Drakoen
6:19 PM GMT on January 25, 2015584. KEEPEROFTHEGATE (Mod)
6:18 PM GMT on January 25, 2015583. KEEPEROFTHEGATE (Mod)
6:17 PM GMT on January 25, 2015582. KEEPEROFTHEGATE (Mod)
6:15 PM GMT on January 25, 2015581. TropicalAnalystwx13
6:14 PM GMT on January 25, 2015Track shifts slightly farther west, could allow for heavier accumulations.
579. TropicalAnalystwx13
6:01 PM GMT on January 25, 2015578. LargoFl
5:54 PM GMT on January 25, 2015Blizzards are dangerous winter storms that are a combination of blowing snow and wind resulting in very low visibilities. While heavy snowfalls and severe cold often accompany blizzards, they are not required. Sometimes strong winds pick up snow that has already fallen, creating a ground blizzard.
Officially, the National Weather Service defines a blizzard as a storm which contains large amounts of snow OR blowing snow, with winds in excess of 35 mph and visibilities of less than 1/4 mile for an extended period of time (at least 3 hours). When these conditions are expected, the National Weather Service will issue a "Blizzard Warning". When these conditions are not expected to occur simultaneously, but one or two of these conditions are expected, a "Winter Storm Warning" or "Heavy Snow Warning" may be issued.
Blizzard conditions often develop on the northwest side of an intense storm system. The difference between the lower pressure in the storm and the higher pressure to the west creates a tight pressure gradient, or difference in pressure between two locations, which in turn results in very strong winds. These strong winds pick up available snow from the ground, or blow any snow which is falling, creating very low visibilities and the potential for significant drifting of snow.
577. KEEPEROFTHEGATE (Mod)
5:53 PM GMT on January 25, 2015Warning: The information on WeatherAlert-Forecast is not guaranteed to be up-to-date and is prone to large errors. Never use for important decision making.
576. LargoFl
5:52 PM GMT on January 25, 2015575. hurricanes2018
5:49 PM GMT on January 25, 2015keep adding more snow on this snowfall map pink color getting bigger by the hour of over 2 feet of snow in pink
574. KEEPEROFTHEGATE (Mod)
5:46 PM GMT on January 25, 2015573. Gearsts
5:45 PM GMT on January 25, 2015572. sar2401
5:44 PM GMT on January 25, 2015I really think there used to be a criteria for cold as well. Some dictionary definitions still mention "intense cold". However, it seems there are only two things now that officially define a blizzard - wind and visibility. This is the NWS definition, complete with the all caps teletype abbreviation. :-)
Blizzard
(abbrev. BLZD)- A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:
Sustained wind or frequent gusts to 35 miles an hour or greater; and
Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than 1/4 mile)
Link
571. hurricanes2018
5:43 PM GMT on January 25, 2015wow two feet on snow for new haven!! i live there
570. hurricanes2018
5:38 PM GMT on January 25, 2015the new GFS got this storm littie more to the west again right next to the coast of northeast
569. wetrain
5:34 PM GMT on January 25, 2015568. Climate175
5:33 PM GMT on January 25, 2015567. TropicalAnalystwx13
5:32 PM GMT on January 25, 2015For comparison, the current forecast for the region:
At the very least, this will be a significant, long duration, and life-threatening blizzard for much of the Northeast, with the potential for historical totals in some locations.
566. wetrain
5:31 PM GMT on January 25, 2015565. washingtonian115
5:30 PM GMT on January 25, 2015564. hurricanes2018
5:28 PM GMT on January 25, 2015From 1pm EST, Mon, Jan 26 Until 12am EST, Wed, Jan 28
Affected Areas
Radar
Jan 25, 12:15pm EST Weather In Motion®
Issued by The National Weather Service
New York City, NY
Sun, Jan 25, 9:53 am EST
... BLIZZARD WATCH REMAINS IN EFFECT FROM MONDAY AFTERNOON THROUGH TUESDAY EVENING...
* LOCATIONS... SOUTHERN CONNECTICUT AND LONG ISLAND.
* HAZARD TYPES... HEAVY SNOW AND BLOWING SNOW... WITH BLIZZARD CONDITIONS LIKELY.
* ACCUMULATIONS... SNOW ACCUMULATION OF 1 TO 2 FEET... WITH LOCALLY HIGHER AMOUNTS POSSIBLE.
* WINDS... NORTH 25 TO 35 MPH WITH GUSTS UP TO 55 MPH.
* VISIBILITIES... ONE QUARTER MILE OR LESS AT TIMES.
* TIMING... HEAVIEST SNOW AND STRONGEST WINDS WILL OCCUR OVERNIGHT MONDAY INTO TUESDAY.
* IMPACTS... EXTREMELY DANGEROUS TRAVEL DUE TO HEAVY SNOWFALL AND STRONG WINDS WITH WHITEOUT CONDITIONS LIKELY. SECONDARY AND TERTIARY ROADS MAY BECOME IMPASSABLE. STRONG WINDS MAY DOWN POWER LINES AND TREE LIMBS.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A BLIZZARD WATCH MEANS THERE IS A POTENTIAL FOR FALLING AND/OR BLOWING SNOW WITH STRONG WINDS AND EXTREMELY POOR VISIBILITIES. THIS CAN LEAD TO WHITEOUT CONDITIONS AND MAKE TRAVEL VERY DANGEROUS.
&&
More Information
... POTENTIALLY HISTORIC WINTER STORM TO IMPACT THE AREA FROM LATE MONDAY INTO TUESDAY... .
563. KEEPEROFTHEGATE (Mod)
5:28 PM GMT on January 25, 2015562. LAbonbon
5:24 PM GMT on January 25, 2015Caleb - I have seen that site, but haven't played too much with it (yet). Thanks!
Looks like the winds will be howling on the Cape - based on the 'point & click', 100 km/h (62 mph).
561. MaxWeather
5:23 PM GMT on January 25, 2015I had a hard time trying to decide over that area... I traced the 6-12" line in between right through BWI...
560. Climate175
5:23 PM GMT on January 25, 2015559. washingtonian115
5:19 PM GMT on January 25, 20151 hr ·
BALTIMORE / DC FRIENDS... THE UPDATED NATIONAL WEATHER SERVICE SNOWMAP FINALLY AGREES WITH MY THINKING... A half foot and more from Baltimore City N & E for grand totals.
4-6" overall. Sharp cutoff from DC and south.
558. beell
5:19 PM GMT on January 25, 2015All my experiences with regurgitation have not been near that useful. So...that's something nice to say.
557. Drakoen
5:16 PM GMT on January 25, 2015Exactly.
Right now my forecast agree with the NWS. General 4-6 inches with the potential for higher amounts.
556. KEEPEROFTHEGATE (Mod)
5:15 PM GMT on January 25, 2015winds just off Avalon off newfoundland showing location wind direction using degrees and wind speed using kmh
555. Sfloridacat5
5:14 PM GMT on January 25, 2015D.C. might not see significant accumulations until late Monday night into Tuesday morning.
I think by Tuesday morning there will be several inches (3-6") on the ground in the D.C. area.