Saturday, February 6, 2010

New All-Time Snowfall Records at Washington Dulles, Baltimore, Wilmington

For related posts, including the latest all-time seasonal record, see:
Midnight Update: This is also the 4th highest 2-day storm total in Washington history and the 2nd highest at Washington National:
THE 17.8 INCH TWO-DAY STORM TOTAL SNOWFALL RECORDED TODAY AT RONALD 
REAGAN WASHINGTON NATIONAL AIRPORT IS THE SECOND HIGHEST TWO-DAY
STORM TOTAL RECORD...SECOND ONLY TO THE 18.7 INCHES FOR NATIONAL
AIRPORT FROM 18-19 FEBRUARY 1979. THIS WOULD ALSO BE THE 4TH
HIGHEST TWO-DAY STORM TOTAL ALL-TIME SNOWFALL FOR WASHINGTON RECORDS
WHICH DATE BACK TO 1871...BEHIND ONLY THE 27-28 JANUARY 1922
KNICKERBOCKER STORM WITH 26.0 INCHES...THE 12-13 FEBRUARY 1899 STORM
WHICH PRODUCED 19.0 INCHES...AND THE 18.7 INCHES WHICH FELL 18-19
FEBRUARY 1979.
The storm total snowfall at Wilmington, Delaware was the largest in history, and the seasonal total snowfall is now the 2nd highest on record:
THE 25.8 INCHES OF SNOW THAT FELL IN WILMINGTON LATE YESTERDAY AND 
TODAY WAS THE GREATEST SNOWFALL IN RECORDED HISTORY.

THE FIVE GREATEST SNOWFALLS AT WILMINGTON:

RANK SNOWFALL DATE
(INCHES)

1 25.8 FEBRUARY 5/6 2010
2 22.2 JANUARY 8/9 1996
3 22.0 FEBRUARY 16/17/18 2003
4 21.7 MARCH 6/7 1912
5 20.0 JANUARY 16/17/18 1907

...SECOND SNOWIEST YEAR (JULY THROUGH JUNE) THUS FAR IN
WILMINGTON...

WITH THE 25.8 INCHES OF NEW SNOW IN WILMINGTON, THE SEASON TOTAL
JUMPED TO 53.9 INCHES. THIS TOTAL NOW RANKS SECOND AND IS ONLY
BEHIND THE 55.9 INCHES THAT FELL IN 1995-1996.

THE TEN SNOWIEST YEARS (JULY THROUGH JUNE) AT WILMINGTON:

RANK SNOWFALL YEARS
(INCHES)

1 55.9 1995-1996
2 53.9 2009-2010
3 49.5 1957-1958
4 46.0 2002-2003
5 45.6 1977-1978
6 44.7 1933-1934
7 44.7 1906-1907
8 44.2 1978-1979
9 44.1 1960-1961
10 43.5 1966-1967
This was the 2nd highest storm total in Philadelphia history, and the season's total at Philadelphia is now the 2nd highest in history:
THE 28.5 INCHES WHICH FELL AT PHILADELPHIA LATE YESTERDAY AND TODAY 
WAS THE SECOND GREATEST SNOWFALL IN RECORDED HISTORY.

THE FIVE GREATEST SNOWFALLS AT PHILADELPHIA:

RANK SNOWFALL DATE
(INCHES)

1 30.7 JANUARY 7/8 1996
2 28.5 FEBRUARY 5/6 2010
3 23.2 DECEMBER 19/20 2009
4 21.3 FEBRUARY 11/12 1983
5 21.0 DECEMBER 25/26 1909

THIS IS ALSO THE FIRST TIME IN RECORDED HISTORY THAT PHILADELPHIA
HAS EXPERIENCED TWO SNOWFALLS IN EXCESS OF 20 INCHES IN THE SAME
WINTER SEASON.

...SECOND SNOWIEST YEAR (JULY THROUGH JUNE) THUS FAR IN
PHILADELPHIA...

WITH THE 28.5 INCHES OF NEW SNOW IN PHILADELPHIA, THE SEASON TOTAL
JUMPED TO 56.3 INCHES. THIS TOTAL NOW RANKS SECOND AND IS ONLY
BEHIND THE 65.5 INCHES THAT FELL IN 1995-1996.

THE TEN SNOWIEST YEARS (JULY THROUGH JUNE) AT PHILADELPHIA:

RANK SNOWFALL YEARS
(INCHES)

1 65.5 1995-1996
2 56.3 2009-2010
3 55.4 1898-1899
4 54.9 1977-1978
5 49.1 1960-1961
6 46.3 2002-2003
7 44.3 1966-1967
8 43.9 1917-1918
9 43.8 1904-1905
10 41.8 1957-1958
Original post: The National Weather Service announced this evening that new all-time snowstorm records have been set at Washington Dulles and Baltimore BWI:
AT 5:10 PM EST THIS AFTERNOON...32.4 INCHES OF TWO-DAY STORM TOTAL   
SNOWFALL WAS RECORDED AT THE NATIONAL WEATHER SERVICE WEATHER
FORECAST OFFICE IN STERLING VA. THIS OBSERVATION RECORDED AT THE
STERLING WEATHER FORECAST OFFICE IS DEEMED CLIMATOLOGICALLY
REPRESENTATIVE OF DULLES INTERNATIONAL AIRPORT DUE TO ITS PROXIMITY
TO THE AIRPORT.

PRELIMINARY INDICATIONS ARE THAT THIS 32.4 INCH TWO-DAY STORM TOTAL
SNOWFALL BREAKS THE PREVIOUS TWO-DAY STORM RECORD OF 23.2" ON 7-8
JANUARY 1996...AND THE PREVIOUS THREE-DAY STORM RECORD OF 24.6" ON
6-8 JANUARY 1996.

AT 4:54 PM EST THIS AFTERNOON...A 24.8 INCH TWO-DAY STORM TOTAL
SNOWFALL WAS ESTIMATED AT BALTIMORE/WASHINGTON INTERNATIONAL
THURGOOD MARSHALL AIRPORT.

PRELIMINARY INDICATIONS ARE THAT THIS 24.8 INCH TWO-DAY STORM TOTAL
SNOWFALL EXCEEDS THE PREVIOUS TWO-DAY STORM TOTAL SNOWFALL RECORD OF
24.4 INCHES FROM 16-17 FEBRUARY 2003.

Blog Posting Delayed by Weather
Snow Totals Updated

Blog posting and updating have been interrupted by an extended power outage and continuing Comcast cable outage. Thank you for your patience.

1 PM Update: Current snow depth on the ground:
Washington National 16"
Dulles 20"
Baltimore/BWI 24"
Original post: Here are some snowfall totals reported by the National Weather Service as of 10:42 am for the Washington/Baltimore area. At noon, Washington National was reporting heavy snow and an increase of 1" to 15". Dulles and BWI both reported moderate snow; BWI increased 1" to a current depth of 22" on the ground.
********************STORM TOTAL SNOWFALL********************  

LOCATION STORM TOTAL TIME/DATE COMMENTS
SNOWFALL OF
/INCHES/ MEASUREMENT

DISTRICT OF COLUMBIA

..DISTRICT OF COLUMBIA

1 NNE WASHINGTON 20.0 959 AM 2/06
AMERICAN UNIVERSITY 19.5 650 AM 2/06 SPOTTER

MARYLAND

..ANNE ARUNDEL COUNTY

1 NNE CROFTON 26.8 730 AM 2/06 LIQ EQUIV 2.17 COCORAHS
2 NW RIVA 25.5 830 AM 2/06
1 W GLEN BURNIE 24.5 710 AM 2/06
BALT-WASH INTL ARPT 23.9 1027 AM 2/06
MILLERSVILLE 23.5 900 AM 2/06
1 S CROFTON 21.0 800 AM 2/06
1 NE GREEN HAVEN 20.0 553 AM 2/06
GREEN HAVEN 19.2 930 AM 2/06
1 NW BELVEDERE HEIGH 18.5 925 AM 2/06
BELVEDERE HEIGHTS 18.0 1011 AM 2/06
3 SSW CROWNSVILLE 18.0 830 AM 2/06
1 NNW PASADENA 18.0 300 AM 2/06
EASTPORT 17.8 830 AM 2/06
1 NW ANNAPOLIS 17.6 900 AM 2/06
1 NNE OWINGS 15.0 700 AM 2/06
1 E CHURCHTON 12.5 845 AM 2/06

..BALTIMORE COUNTY

1 NW RANDALLSTOWN 25.0 810 AM 2/06
1 W HAMPTON 25.0 900 AM 2/06
1 E OELLA 25.0 800 AM 2/06
ESSEX 24.5 930 AM 2/06
2 NE CATONSVILLE 24.0 800 AM 2/06 SPOTTER
2 SSE HAMPSTEAD 22.5 900 AM 2/06
1 NW PERRY HALL 20.0 744 AM 2/06
1 ESE TIMONIUM 19.0 910 AM 2/06
1 ESE GLYNDON 19.0 745 AM 2/06 SPOTTER
2 NW LONG GREEN 18.0 900 AM 2/06
PARKVILLE 17.0 549 AM 2/06
1 ENE PARKVILLE 16.0 630 AM 2/06 SPOTTER
1 SE COCKEYSVILLE 14.2 420 AM 2/06
1 NNW PARKVILLE 13.2 310 AM 2/06 SPOTTER

..BALTIMORE CITY

PIMLICO 24.5 930 AM 2/06
1 S GWYNN OAK 24.0 945 AM 2/06
2 ESE ARLINGTON 23.0 900 AM 2/06
BALTIMORE 20.0 434 AM 2/06 THUNDER
1 W PARK HEIGHTS 19.5 930 AM 2/06

..FREDERICK COUNTY

2 NE JEFFERSON 26.5 850 AM 2/06
JEFFERSON 23.5 700 AM 2/06
POINT OF ROCKS 22.1 930 AM 2/06
EMMITSBURG 22.0 800 AM 2/06 SPOTTER
4 SSW FREDERICK 22.0 700 AM 2/06
3 ESE CAVETOWN 21.0 622 AM 2/06
1 WNW NEW MARKET 20.5 725 AM 2/06
NEW MARKET 20.0 730 AM 2/06

..HOWARD COUNTY

2 W ELKRIDGE 30.3 600 AM 2/06 SWE 2.73- 3-4 HR RATE
2 N COLUMBIA 27.9 900 AM 2/06
1 ESE ELLICOTT CITY 26.0 800 AM 2/06
1 WSW SAVAGE 25.0 700 AM 2/06 COCORAHS
1 SSE SIMPSONVILLE 24.5 655 AM 2/06 SPOTTER LIQ EQUIV 2.09
1 ENE GLENELG 21.0 418 AM 2/06 SPOTTER
2 SE GAITHER 20.0 700 AM 2/06 COCORAHS
1 N SAVAGE 20.0 630 AM 2/06 SPOTTER

..MONTGOMERY COUNTY

2 ESE GERMANTOWN 25.9 1014 AM 2/06
1 NW ROCKVILLE 24.5 717 AM 2/06
2 NE CLARKSBURG 24.5 700 AM 2/06
2 WSW DAMASCUS 23.0 825 AM 2/06
1 SE NORBECK 22.6 841 AM 2/06
1 NNE GLENMONT 22.1 735 AM 2/06
1 SE OLNEY 22.0 927 AM 2/06
1 S OLNEY 21.0 900 AM 2/06 1.97 LIQ EQUIV
POOLESVILLE 21.0 840 AM 2/06
1 E CLOVERLY 21.0 934 AM 2/06
1 N FOUR CORNERS 19.5 740 AM 2/06
GLEN ECHO 18.8 800 AM 2/06
FOUR CORNERS 17.0 340 AM 2/06 SPOTTER
1 NNW SOMERSET 16.5 730 AM 2/06 SPOTTER
2 WNW OLNEY 14.0 700 AM 2/06 SPOTTER

..PRINCE GEORGES COUNTY

1 SSW BELTSVILLE 20.0 920 AM 2/06
3 ENE GLENN DALE 20.0 700 AM 2/06 SPOTTER
BOWIE 19.0 800 AM 2/06
FRIENDLY 18.5 1016 AM 2/06
1 NNE GREENBELT 18.0 742 AM 2/06
1 N FRIENDLY 17.0 1000 AM 2/06
HYATTSVILLE 16.8 819 AM 2/06
CAMP SPRINGS 14.0 1000 AM 2/06 NCEP HPC

..ST. MARYS COUNTY

SOTTERLEY 11.5 945 AM 2/06
1 ESE HILLVILLE 9.5 600 AM 2/06 SPOTTER
1 NNE HOLLYWOOD 9.0 700 AM 2/06 SPOTTER
COMPTON 9.0 900 AM 2/06 MIXED WITH SLEET

VIRGINIA

..ARLINGTON COUNTY

1 NNE BAILEYS CROSSR 16.2 400 AM 2/06 SPOTTER
REAGAN NATIONAL AIRP 14.4 1026 AM 2/06
2 E BARCROFT 13.5 629 AM 2/06

..CITY OF ALEXANDRIA

1 SSW ALEXANDRIA 16.9 800 AM 2/06

..CITY OF MANASSAS

1 ESE MANASSAS 16.0 800 AM 2/06
1 W MANASSAS PARK 14.3 547 AM 2/06

..FAIRFAX COUNTY

2 NE CHANTILLY 24.0 800 AM 2/06
2 N RESTON 21.0 1023 AM 2/06
1 SE CENTREVILLE 20.0 900 AM 2/06
1 NNE HERNDON 20.0 945 AM 2/06
1 SE THE I66 AND I49 19.0 1018 AM 2/06
1 W CENTREVILLE 18.7 830 AM 2/06 2.10 LIQUID
RAVENSWORTH 18.0 845 AM 2/06
VIENNA 16.0 700 AM 2/06
LORTON 14.3 830 AM 2/06 USDA MET

..FAUQUIER COUNTY

MARSHALL 24.0 630 AM 2/06 NWS EMPLOYEE
WARRENTON 19.5 800 AM 2/06
OPAL 18.0 1000 AM 2/06

..LOUDOUN COUNTY

2 WSW LEESBURG 25.0 500 AM 2/06
BLUEMONT 25.0 929 AM 2/06
LEESBURG 24.0 900 AM 2/06
3 WSW ASHBURN 23.0 745 AM 2/06
ASHBURN 22.0 700 AM 2/06 THUNDER AT 635 AM
1 E STERLING PARK 22.0 715 AM 2/06 SPOTTER
1 SSW ARCOLA 21.2 900 AM 2/06
3 SSW ARCOLA 21.0 715 AM 2/06 NWS EMPLOYEE
MIDDLEBURG 20.0 728 AM 2/06
2 NNW DULLES INTERNA 20.0 645 AM 2/06 WFO STERLING CO-OP OB
DULLES INTERNATIONAL 18.9 1036 AM 2/06
1 NE ASHBURN 18.8 600 AM 2/06 NWS EMPLOYEE
3 NW DULLES INTERNAT 17.5 435 AM 2/06

..PRINCE WILLIAM COUNTY

GAINESVILLE 20.5 900 AM 2/06
1 SSW WOODBRIDGE 12.5 500 AM 2/06 COCORAHS

Washington, Baltimore Set New Snowfall Records

For related posts, see:
As noted earlier, Washington Dulles easily broke its daily snowfall record for Feb. 5. The liquid precipitation for the day of 0.99" also more than doubled the old record of 0.46" set in 1998.

The 8.7" of snow at Washington National broke the more substantial record of 7.5" set in 1892. The season's total so far of 36" puts 2009-10 within striking distance of surpassing the number 10 seasonal total of 37.7" in 1979. The month-to-date amount of 12", however, is still over 5" short of breaking into the top 10 February list.

The 7.8" at BWI breaks the old daily record of 6.4" in 1899.

Friday, February 5, 2010

Washington Super Storm Snowfall Scoreboard: Going for the Gold

For related posts, see:
11 PM Update: Colder temperatures and higher snowfall rates have picked up the accumulations significantly since early this evening. National now has 8" on the ground, Dulles has 10" of new snow, for a total of 11" on the ground. Baltimore/BWI has 6".

Original post:
Super Storm!
Armageddon!
Apocalypse!
Wall-to-wall coverage of the checkout lines at Giant supermarket, snow shovel buyers at Strosnider's Hardware and Home Depot. Don't forget the live shot from the salt domes.
Do they have your attention yet?

The much anticipated Blizzard of 2010 is making itself felt in the Washington metro area. In what must be an unprecedented move, the normally-cautious National Weather Service at 12:34 issued a prediction that puts the all-time Washington snowfall record in jeopardy:
...RECORD SNOWFALL FORECAST IN THE BALTIMORE-WASHINGTON DC REGION...

EXTREMELY DANGEROUS WINTER WEATHER CONDITIONS DEVELOPING TONIGHT
GUSTY NORTHEAST WINDS 20 TO 30 MPH WITH VISIBILITIES FREQUENTLY
FALLING BELOW ONE-QUARTER MILE DUE TO HEAVY SNOW WILL DEVELOP
TONIGHT TO PRODUCE NEAR-BLIZZARD AND EXTREMELY HAZARDOUS WINTER WEATHER
CONDITIONS TONIGHT THROUGH SATURDAY MORNING. TRAVEL IS HIGHLY
DISCOURAGED TONIGHT AND WILL BE VERY DANGEROUS.
LOOKING BACK AT THE BIGGEST STORM OF RECORD FOR WASHINGTON DC... THE
JANUARY 1922 KNICKERBOCKER STORM...28.0 INCHES OF SNOW WAS
PRODUCED FROM 3.02 INCHES OF LIQUID WATER. CURRENT FORECASTS FOR
THIS EVENT HAVE TOTAL LIQUID FALLING FROM THIS STORM APPROACHING 3
INCHES...WHICH ACCORDINGLY WOULD CREATE A SNOWFALL THAT WILL RIVAL
THE KNICKERBOCKER STORM TOTAL. GENERALLY ACROSS THE REGION...20 TO
30 INCHES OF SNOW WILL FALL BY SATURDAY EVENING.
BALTIMORES RECORD OF 26.8 INCHES FROM THE PRESIDENTS DAY FEBRUARY 2003
STORM WILL ALSO BE THREATENED.
Snow began falling in the mid to late morning; here in Montgomery County MD it started with some very tiny flakes and a temperature of 37° at 10:40. The pace picked up into early afternoon, but even after several hours of precipitation, the temperature was only down to 34.5°. The above-freezing temperatures kept paved surfaces wet for several hours. Although residential streets are now snow-covered, conditions were not treacherous enough to prevent the UPS man from delivering on time a reinforcing supply of warm Gold Toe Socks.

It's still early into what is shaping up as a major storm, but in much of the metro area, it would have to be rated as underperforming its advertised target of 2-4" this afternoon. As of 4 pm, only Dulles was in the range with 3.4", which was a record for the date, since the old one was a puny 1" in 2001. National was at 1.1", and BWI had only a trace.

We noted here earlier that the major risk to the forecast for a record-breaking event was the liquid vs. frozen precipitation issue, and that is certainly still the case. In the past hour or so, radar indicates that the rain/snow line has advanced northward from Richmond to near Fredericksburg.

The chart shows the accumulated frozen and liquid precipitation at Washington National through 6 pm. The scales are in the ratio of 10:1 of frozen to liquid, so if the green is ahead of the blue, the water content is relatively higher (lower frozen to liquid ratio). Check back for updates as conditions warrant through the storm.

Image (click to enlarge): Washington National accumulated frozen vs. liquid precipitation, CapitalClimate chart from National Weather Service data

Thursday, February 4, 2010

All-Time Record Snowfalls for Washington and Baltimore

For related posts, see:
The list of all-time biggest snowstorms in Washington and Baltimore from the National Weather Service, modified to include the record storm of December 2009:
THE TOP 11 SNOW STORMS FOR WASHINGTON ARE AS FOLLOWS...

1ST JANUARY 27-28 1922......28.0 INCHES
2ND FEBRUARY 11-13 1899......20.5 INCHES
3RD FEBRUARY 18-19 1979......18.7 INCHES
4TH JANUARY 6-8 1996......17.1 INCHES
5TH FEBRUARY 15-18 2003......16.7 INCHES
6TH FEBRUARY 11-12 1983......16.6 INCHES
7TH DECEMBER 18-19 2009. . . 16.4 INCHES
8TH FEBRUARY 15-16 1958......14.4 INCHES
9TH FEBRUARY 7 1936......14.4 INCHES
10TH FEBRUARY 16-18 1900......14.3 INCHES
11TH JANUARY 29-30 1966......13.8 INCHES

THE TOP 11 SNOW STORMS FOR BALTIMORE ARE AS FOLLOWS...

1ST FEBRUARY 15-18 2003......28.2 INCHES
2ND JANUARY 27-29 1922......26.5 INCHES
3RD FEBRUARY 11-12 1983......22.8 INCHES
4TH JANUARY 7-8 1996......22.5 INCHES
5TH DECEMBER 18-19 2009......22.2 INCHES
6TH MARCH 29-30 1942......22.0 INCHES
7TH FEBRUARY 11-14 1899......21.4 INCHES
8TH FEBRUARY 18-19 1979......20.0 INCHES
9TH MARCH 15-18 1892......16.0 INCHES
10TH FEBRUARY 15-16 1958......15.5 INCHES
11TH JANUARY 25 2000......14.9 INCHES

Expected Mid-Atlantic Blizzard Fueled by Massive Moisture

For related posts, see:
Feb. 5 Update: The final total of 2.51" at Jackson MS blew away the old record of 1.75" from 1956.

Midnight Update: Unofficially, Jackson received at least another 0.57" before midnight, which would break the daily record. An additional 1.20" at Meridian pushed that total over 2". Gulfport MS got 2.26" in 6 hours. The total at New Orleans was also over 2". Mobile AL had 1.76" in 6 hours.

Original post:
The storm system now developing along the western Gulf Coast has prompted widespread Winter Storm Warnings through the Mid Atlantic region and even a Blizzard Warning for the New Jersey and Delaware coasts. Precipitation amounts can't be taken too literally, since precipitation is the most difficult of the various meteorological parameters to forecast, but model forecast accumulations have continued to increase. This afternoon's output from the GFS model, for example, shows total liquid precipitation amounts (in the dark red area) from 2.5"-3" through much of Virginia and the southern half of Maryland.

Rainfall reports today from the Gulf Coast indicate that this is indeed a very moist system. The National Weather Service office in Jackson, Mississippi said this afternoon:
THURSDAY MORNING ALL THE WAY THROUGH THURSDAY NIGHT WAS PERFECT   
WEATHER IF YOU WERE A DUCK. HOWEVER...FOR THE REST OF US...IT WAS A
COOL AND VERY SOGGY DAY ACROSS THE ENTIRE REGION. HIGH TEMPERATURES
WERE STIFLED IN THE MID AND UPPER 40S AREAWIDE DUE TO THE EXCESSIVE
CLOUD COVER AND RAINY CONDITIONS. A FLASH FLOOD WATCH REMAINS IN
EFFECT FOR SOUTHERN AND SOUTHEAST MISSISSIPPI THROUGH MIDNIGHT
FRIDAY MORNING.
Preliminary daily climate reports in the region show heavy rainfall amounts, although it appears that no records have been set so far. Some daily precipitation reports through 4 pm CST include (record amount in parentheses):
Hattiesburg MS   2.00" (5.12")
Jackson MS 1.20" (1.75")
Meridian MS 0.83" (3.24")
Vicksburg MS 0.90" (1.83")
Beaumont TX 1.55" (2.91")
Lake Charles LA 1.58" (3.34")
Lafayette LA 2.08" (3.12")
New Orleans LA 1.58" (3.00")
Images (click to enlarge): Precipitation forecast for 48 hours ending Saturday afternoon, Feb. 6, from The Weather Channel; GFS model precipitation forecast for 60 hours ending 1 pm Sunday, Feb. 7

Washington's Top 10 February Snow Totals

Feb. 7 update: click here.

For related posts, see:
With 3.3" of snow recorded so far this February and a major storm widely expected this weekend, how much would it take to break into the all-time top 10 of Washington February snow totals? Generally, it takes at least one large storm to reach the 17.2" minimum for the top 10.

In 1958, #10 on the list, 14.4" fell on Feb. 15-16. The only other measurable snow that month was 2.8" on the 1st. In December of that winter, 11.4" had already fallen on Dec. 3-4, and the season wound up with another double digit month in March spread over 3 separate storms. That was enough to put 1957-58 into 7th place for seasonal totals.

In 1961, #9, 3 storms provided 8.3" on Feb. 3-4, 6.4" on the 8th, and 3.3" on the 12th. No other measurable snow fell the rest of the month, however, and the temperature reached 70° twice, on the 19th and the 27th.

February 1934, #8, also had no single storm over 10": 8.1" on the 1st-2nd, 1.5" on the 5th-6th, 1.8" on the 19th, and a few other small amounts.

February 1936, #6, saw 14.4" on the 7th, but the remainder of the total was made up of 1.8" on the 18th and scattered minor amounts on 3 other days.

In 1983, there was a major storm (possibly an analog to the current one) with 16.6" on the 10th-11th. The only other measurable snow was 4.4" on the 6th. That was enough to put that year into 4th place.

The 2nd and 3rd place years, 1979 and 2003, had the infamous President's Day Storms I and II, 18.7" on the 18th-19th and 16.7" on the 15th-18th, respectively.

Wednesday, February 3, 2010

Snow Obsessive-Compulsive Disorder Outbreak Expected in DC Area

For related posts, see:
Major Winter Storm of Hysterical Proportions?

Feb. 3, Midnight Update: The GFS model continues to be consistent, a little drier (more realistic), a little less warm than the NAM. Although precipitation amounts are still very high, the rain/snow line is still a concern for snowfall amounts, especially in the immediate Washington/Baltimore area.

Feb. 3, 9:35 PM Update: The evening (00Z) NAM model has reached 60 hours within the last few minutes. There are no surprises, although the forecast storm position for Saturday morning is closer to the coast. This brings in more warm air and increases the chances for precipitation mixing or changing to rain.

Feb. 3, 5 PM Update: The afternoon model run, with 72-hour results being posted just within the last few minutes, is confirming the general story of heavy precipitation, mainly snow, beginning during the day on Friday and extending into Saturday. The main difference is that precipitation amounts have increased from earlier runs.

Feb. 3, 4 PM Update: The Washington/Baltimore local forecast discussion has been updated. As indicated here earlier, mixing or changeover to rain will be a major issue, but some very heavy snow amounts are still likely.
BY MIDDAY FRI...MODERATE-HEAVY PRECIP WILL BE PUSHING ACROSS THE ERN
SEABOARD AND INTO THE MID ATLC. ENOUGH COLD AIR WILL BE IN PLACE /E
OF I-95/ FOR AN ALL-SNOW P-TYPE /POSSIBLY A BRIEF PERIOD OF A RAIN-
SNOW-SLEET MIX AT ONSET/. ALONG AND E OF I-95 WILL CERTAINLY BE THE
MIX LINE FOR MUCH OF THE DAY...W/ A CHANCE OF A SNOW CHANGEOVER
LATER IN THE EVENING-OVERNIGHT AS A SFC LOW STRENGTHENS OFF THE
COAST OF CAPE HATTERAS AND PULLS SOME OF THE COLDER AIR BACK SWD. AS
THIS LOW STRENGTHENS...MUCH LIKE THE DEC STORM...WINDS WILL
STRENGTHEN OVER THE BAY AND COASTAL REGIONS /NEARING GALE WARNING
FROM SAT AFTN-EARLY SUN/. BACK TO THE WEST...SNOW WILL CONTINUE OVER
THE REGION AND BE ESPECIALLY HEAVY AND CONTINUOUS LATE FRI INTO
EARLY SAT. EVEN AS THE SFC LOW TAKES A BULK OF THE SYSTEM OFF THE
MID ATLC COAST SAT MORNING...SNOW WILL CONTINUE ALL THE WAY BACK
INTO THE OHIO VLY /HEAVIEST EAST OF THE APLCNS/. ANOTHER ROUND OF
LIGHT-MODERATE SNOW WILL CONTINUE THRU MUCH OF THE DAY FOR THIS
REGION ASSOCIATED W/ THE PASSING UPPER TROF AXIS.
Note that the first reference to p-type (precipitation) is undoubtedly a typo and should refer to all or mostly snow west of I-95, rather than east.

Feb. 3 PM Update: At 2:45, the National Weather Service issued a Winter Storm Watch for the Washington, DC/Baltimore area and much of adjoining central Maryland and northern Virginia for Friday and Saturday, Feb. 5-6:
WINTER STORM WATCH IN EFFECT FROM FRIDAY MORNING THROUGH
SATURDAY EVENING...

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A
WINTER STORM WATCH...WHICH IS IN EFFECT FROM FRIDAY MORNING
THROUGH SATURDAY EVENING.

* PRECIPITATION TYPE...SNOW.

* ACCUMULATIONS...THIS STORM IS LIKELY TO PRODUCE 12 OR MORE
INCHES OF SNOW IN THE WATCH AREA...WITH A GOOD CHANCE FOR
LOCALIZED AMOUNTS OVER 20 INCHES.

* TIMING...SNOW IS EXPECTED TO BEGIN LATE MORNING
FRIDAY...CONTINUING THROUGH SATURDAY EVENING.

* TEMPERATURES...HIGHS IN THE LOWER TO MID 30S FRIDAY. FRIDAY
NIGHT AND SATURDAY...TEMPERATURES WILL BE 25 TO 30 DEGREES.

Feb. 3 Noon Update: The latest model run, posted within the last hour, continues to show a major storm off the Mid Atlantic coast by Saturday afternoon. The timing has accelerated a bit, however, and the precipitation amounts, although still heavy, are a little lower.

The storm evolution is now also within range of the higher-resolution NAM model. In general, it tells a similar tale, but with some subtle differences. The storm is slower, wetter, but also a little warmer.

The bottom line at this point approaching 48 hours to the onset of the event:
  • A major storm is extremely likely to develop
  • Precipitation will probably be heavy
  • Enough cold air will be in place for the majority to be snow in parts of the Mid Atlantic area
So what could possibly go wrong? Just ask the crack chefs at Momma Nature's Weather Grill why they keep such a large array of mops and other cleaning tools in their kitchen. The major risk to this forecast is the potential mixing or changeover of precipitation to rain for a while, especially as the storm is initially strengthening off the coast.

Image (click to enlarge): Computer model forecast for 7 am Saturday, Feb. 6, shows a strong storm moving away from the Mid Atlantic Coast. Precipitation amounts in the Washington area would be in the range of 3-6" of snow in the previous 6 hours, with larger amounts earlier. Implied temperatures would be cold enough for snow southward through nearly all of Virginia.

Feb. 2 Evening Update: Despite some amateurs flaunting their crystal balls, as of 9:16 pm, the National Weather Service is prudently reiterating their guidance:
THE FORECAST REFLECTING A GOOD CONSENSUS W/ LONG RANGE GUIDANCE...
WHICH POINTS TOWARD A FAIRLY SIMILAR SET-UP FROM THE LATE DEC STORM
/AT LEAST IN MID LEVEL DYNAMICS UPPER VORT MAX WELL WEST OF THE
STRENGTHENING SFC LOW OFF CAPE HATTERAS-VA TIDEWATER/. STILL TOO
EARLY TO FOCUS ON AREAS-ACCUMULATION...THO POPS HAVE BEEN RAISED
INTO CATEGORICAL RANGE FOR LATE FRI-THRU EARLY SAT. ALSO...THIS
SYSTEM APPEARS TO HAVE MORE WARM AIR WRAPPED INTO IT. ENOUGH COLD
AIR WILL BE ASSOCIATED W/ THE APPROACHING UPPER LOW ON FRI TO BE
MAINLY ALL-SNOW FOR THE ENTIRE CWA /OUTSIDE OF LOWER SRN MD-NEAR
BAY AREAS WHICH WOULD BE MORE OF A RAIN-SNOW MIX/.

Feb. 2 PM Update: This afternoon's view of Saturday's map shows a distinct jog to the north in the storm position, even in relation to the model run made just 6 hours earlier from this morning's data. At the 96-hour range, the general picture of a classic East Coast storm is coming into focus, but even a 72-hour forecast has an average error in storm location of about 175 miles, which makes a big difference in the weather at any particular location. For what it's worth, however, (and it can't be taken literally) the model is projecting an area of 1.5"+ of precipitation from the Carolinas northward through Virginia and into the southern two-thirds of Maryland. From about a line from DC to Baltimore northward, much of this would be frozen, so snow amounts of a foot or more would not be out of the question in some places. Assigning specific numbers, even in probabilistic terms, however, at this point is pure hype-casting.

Feb. 1 Update: This just in: Model forecasts at the range of 5 or 6 days can have errors. Here's this afternoon's version of a forecast for the same time on Saturday. Notice any differences?
  • The Hudson Bay high is not as cold and is centered further west.
  • The low is still strong but not as intense.
  • The heaviest precipitation is further south.
Some of the differences are the result of faster timing. Other models have different ideas. So far, the indications are that the odds for snow are more favorable south of the Mason-Dixon line than north. At least some fanatics are likely to be disappointed. Back to our regular programming.

Original post:
After a week of hyperventilating over the prospect of what turned out to be 4-6" of mostly air in the Washington metro area, snow obsessive-compulsive disorder victims should brace themselves for the coming week. It's waaay too early to assign percentages, as a certain blog (they know who they are) does to pimp out their eyeball count, but the models are hinting at the possibility of a major east-coast storm for next weekend, Feb. 5-6.

The latest run this afternoon of the GFS, the primary U.S. computer model, shows a pool of extremely cold air anchored over Hudson Bay and a strong low-pressure area developing off the southeast U.S. coast (click image to enlarge). The 6-day forecast, for 1 pm on Saturday, shows heavy precipitation (as much as 1" in 6 hours, roughly 10" of snow) from near Washington, DC southeast to Tidewater Virginia. Temperatures are indicated to be cold enough for snow as far south as central Virginia and eastward to the middle of the Maryland Eastern Shore. In short, all the ingredients from Momma Nature's Weather Grill cookbook.

Western Washington's Warmest January

The National Weather Service reports that January 2010 was the warmest on record in Seattle, including records dating to 1891 at the Federal Building downtown. The average of 47.0° was 0.4° above the old record in 2006 and 6.1° above the long-term average. This was even above the normal average high of 45.8°.
SEATTLE RECORDS INCLUDING THE FEDERAL BUILDING 
(1891 TO PRESENT)

1. 47.0 2010 **
2. 46.6 2006
3. 46.4 1995 **
4. 45.7 2003 **
45.7 1931
Bellingham, Washington tied its record for January. Olympia, Quillayute, and Hoquiam had their second warmest Januaries.

Tuesday, February 2, 2010

2009-10 vs. Record Snow Seasons

Feb. 7 update: click here.

For related posts, see:
Feb. 3 Update: The updated climate report for today posted within the last few minutes adds another 1.2" after midnight for a storm total of 3.3" and season-to-date of 27.3". For the other major regional locations, the storm snowfall and seasonal totals are:
Dulles trace today, no change  
BWI 4.9"/35.6"
The National Weather Service chart shows the overall Feb. 2-3 snowfall pattern for the Washington/Baltimore region:


Midnight Update: The chart has been updated to include the 2.1" reported through midnight tonight. The season's total of 26.1" is now just behind the 25th place season of 1982-3 with 27.6". Here are the other regional Feb. 2 daily and season-to-date totals:
Dulles 4.0"/31.1"
BWI 3.0"/33.7"
The BWI total is the 22nd highest in Baltimore records dating back to 1883. The record highest is 62.5" in 1995-6.

Tune back in on Wednesday for final storm totals.

Original post:
Not counting the snow falling tonight, the Washington, DC seasonal snowfall total of 24" is the 32nd highest since records began in 1888. This year is also the highest since the number 6 season of 2002-3 with 40.4".

How does the year so far stack up against the top snow seasons? The chart shows month-by-month and seasonal totals for the current season and the top 10, including the all-time record of 54.4" in 1898-99. The chart will be updated periodically during the rest of the season as conditions warrant.

Image (click to enlarge): Washington, DC monthly and seasonal snow totals for 2009-10 and record top 10 years; CapitalClimate chart from National Weather Service data, background image © Kevin Ambrose

Monday, February 1, 2010

January 2010 Temperature Review: "Most Average" Since 1987

The new decade began with a cold first 2 weeks in the Washington DC area, followed by a warmer 2 weeks. A cold last 3 days brought the average of 35.3° for January 2010 down to within +0.4° of the 1971-2000 normal. This marked the 5th out of the last 6 years in which January has been above average. In the 11 years beginning in 2000, 8 have been above average. This January's average was also the closest to the long-term mean since 1987, when temperatures averaged just 0.2° below what is now the current normal. In fact, 2010 is tied with 1956 (-0.4°) for 11th closest to average out of 140 years of data.

There were 23 days with lows of 32° or below, and 6 of these failed to reach a high above freezing. These were a little more than the normals of 20.7 and 4.6, respectively.

Heating degree days totaled 914, just 0.3% below average. For the season the total is 2341, 2.5% below average.

Despite the frenzy of the snow obsessive-compulsives, the only statistic which really stands out for this January is the precipitation deficit. Following an excessively wet December, the year is starting out at less than 50% of average. The preliminary total of 1.36" may have to be revised upward, however, as December's was. The reported 0.13" of liquid associated with 6.4" of snow on the 30th would imply an astonishingly high ratio of over 49:1 of liquid to frozen precipitation. Including the measly 1" of powder which fell on the 8th, the total snowfall was only a little more than 1" above average.

Images (click to enlarge): Washington DC temperature departures from average, daily Jan. 2010, monthly 2000-2010 and 1871-2010; CapitalClimate charts from National Weather Service data

Seasonal Outlook

Latest seasonal forecast: Click here.


Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.