Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 060850 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 350 AM EST FRI MAR 6 2015 .SYNOPSIS... HIGH PRESSURE BUILDS OVERHEAD TODAY...THEN SETTLES OVER THE SOUTHEASTERN STATES THROUGH THIS WEEKEND. A WEAK COLD FRONT CROSSES THE MID-ATLANTIC SATURDAY NIGHT WITH HIGH PRESSURE THEN BUILDING OVERHEAD THROUGH SUNDAY NIGHT. LOW PRESSURE MOVES ALONG THE CAROLINA COAST TUESDAY WITH A COLD FRONT CROSSING THE MID-ATLANTIC TUESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CENTER OF SFC HIGH PRESSURE IS OVER THE LOWER MS VALLEY THIS MORNING. STILL A PRESSURE GRADIENT OVER THE REGION...ALTHOUGH A FEW SHELTERED OBS ARE 3 KT OR LESS. THESE TWO FACTORS ARE COMBATING EACH OTHER IN THE RESULTING WIND CHILLS...AS TEMPS ARE FALLING A LITTLE MORE SLOWLY THAN FORECAST. WILL KEEP THE ADVISORY GOING UNTIL 10 AM AS CRITERIA STILL REMAINS POSSIBLE. THE HIGH WILL SLIDE EAST TODAY...RESULTING IN QUIET BUT VERY COLD CONDITIONS WITH LOW LEVEL THERMAL TROUGH OVERHEAD. HIGHS WILL LIKELY FALL SHORT OF THE FREEZING MARK EXCEPT IN CENTRAL VA...SOME 20-25 DEGREES BELOW NORMAL. MOISTURE FIELDS INDICATE POSSIBLE STRATOCU...MAINLY W OF THE BLUE RIDGE...AND ADVANCING MID/HIGH CLOUDS LATE AHEAD OF A SHORT WAVE TROUGH. TEMPS WILL FALL AGAIN TONIGHT...AND WITH A WEAKER GRADIENT AND SNOW PACK...EXPECT ANOTHER NIGHT OF TEENS AND SINGLE DIGITS. BLENDED IN ECMWF DATA WITH CURRENT FORECAST WHICH CAPTURES AREAL DISTRIBUTION WELL. SLIGHTLY HIGHER DEWPOINTS AND PERHAPS SOME CLOUD COVER ASSOCIATED WITH THE UPPER TROUGH MAY LIMIT THE FALL. WITH THE CENTER OF THE HIGH TO THE SE BY SATURDAY...RETURN FLOW WILL HELP TEMPERATURES REBOUND NICELY FROM THE COLD MORNING. HOWEVER HIGHS WILL STILL BE BELOW NORMAL. CLOUDS WILL INCREASE LATE IN THE DAY AHEAD OF ANOTHER WEAK NORTHERN STREAM TROUGH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... NO LONGER A SIMPLE WARMING TREND THIS WEEKEND THROUGH MIDWEEK AS PREVIOUSLY THOUGHT. THE SFC HIGH DOES REMAIN ANCHORED OVER THE SERN CONUS. HOWEVER...A WEAK COLD FRONT FROM A LOW OVER THE ST. LAWRENCE VALLEY SHIFTS EAST ACROSS THE MID-ATLANTIC SATURDAY NIGHT. EXPECT AN INCH OF UPSLOPE SNOW WEST FROM THE ALLEGHENY FRONT...WITH JUST CLOUDS EAST ACROSS THE CWA. WEST FLOW SUNDAY WILL DOWNSLOPE AND WARM FOR MID TO UPR 40S N AND LOW TO MID 50S S. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... SFC HIGH SETTLES OVER THE AREA SUNDAY NIGHT. THIS IS DOWNSTREAM OF A SRN JET STREAM TROUGH OVER THE SRN PLAINS. THIS TROUGH WILL PRODUCE A LOW OFF THE CAROLINA COAST MONDAY NIGHT/TUESDAY. RAIN FROM THE PRECIP SHIELD COULD SKIRT THE SRN PORTIONS OF THE CWA. WENT A LITTLE ABOVE WPC GUIDANCE WITH 40 POPS TUESDAY FOR SRN MD AND CHANCES FOR SRN HALF OF CWA AND EAST FROM I-95. SO FAR THIS LOOKS TO BE RAIN. THOUGH SHOULD PRECIP COME IN EARLIER AND BE FARTHER NORTH...SOME MIX OF SLEET OR FREEZING RAIN WOULD BE POSSIBLE. UPR TROUGH SETS UP OVER NERN CONUS WEDNESDAY...PROGRESSING EAST THURSDAY. THIS WILL INCREASE WEST WINDS OVER THE AREA...BUT EXPECT DRY AND NEAR NORMAL TEMPERATURES. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS ARE LIKELY THROUGH THE TAF PERIOD UNDER HIGH PRESSURE. THE ONLY EXCEPTION WOULD BE POSSIBLE STRATOCU AT MRB TODAY WHICH MAY FALL INTO THE MVFR CATEGORY IF THEY BECOME BKN. THINK THIS IS A SMALL PROB. ALSO A SMALL SUBSET OF GUIDANCE SHOWING POSSIBLE VSBY REDUCTIONS LATE TONIGHT AS SLIGHTLY HIGHER DEWPOINTS WORK IN...BUT AM NOT SOLD ON THESE SOLUTIONS YET WITH THE DRY ARCTIC AIRMASS IN PLACE. NORTHERLY WINDS AROUND 10 KT TODAY BECOME LIGHT/VRB BY EVENING...THEN SOUTHERLY SATURDAY AROUND 10 KT. VFR CONDS SATURDAY NIGHT THROUGH MONDAY NIGHT. LIGHT SW FLOW SATURDAY NIGHT BECOMES WLY BEHIND A WEAK COLD FRONT. LIGHT W/NW FLOW THEN THROUGH MONDAY. LIGHT RAIN POSSIBLE TUESDAY AS LOW PASSES THE CAROLINA COAST. && .MARINE... OCCASIONAL SCA LEVEL GUSTS CONTINUE ON THE WATERS EARLY THIS MORNING. WILL MONITOR THE NEED FOR POSSIBLE EXTENSION FOR THE SEGMENTS WHICH EXPIRE AT 6 AM. HOWEVER...ALL GUSTINESS SHOULD SUBSIDE BY MIDDAY AS HIGH PRESSURE BUILDS IN. BY SATURDAY AFTERNOON SOUTHERLY WINDS DEVELOP BUT APPEAR TO STAY BELOW SCA LEVELS. LIGHT SWLY FLOW SATURDAY NIGHT...THEN LIGHT WLY/NWLY FLOW SUNDAY THROUGH MONDAY. LIGHT RAIN POSSIBLE TUESDAY AS A LOW PASSES THE CAROLINA COAST. && .HYDROLOGY... ICE JAM APPEARS TO NOT BE BROKEN YET ON CACAPON RIVER NEAR GREAT CACAPON. WILL CONTINUE TO MONITOR RISES THERE AND ANY OTHER RISES. ICE JAMS APPEAR TO HAVE BROKEN ON GOOSE CREEK IN LEESBURG. && .CLIMATE... SNOWFALL DURING METEOROLOGICAL WINTER (DECEMBER 1ST THROUGH FEBRUARY 28TH...OR 29TH IF IT IS A LEAP YEAR) WAS NEAR NORMAL AT OUR THREE MAIN CLIMATE SITES. HOWEVER...ADDING EARLY SEASON SNOWFALL FROM NOVEMBER AND THE RECENT SNOWFALL SO FAR IN MARCH PUSHES THE ANNUAL SNOWFALL TOTALS ABOVE NORMAL. BELOW IS A TABLE OF NORMAL ANNUAL SNOWFALL (RECORDED FROM JULY 1ST OF A GIVEN YEAR TO JUNE 30TH OF THE FOLLOWING YEAR TO ENCOMPASS THE ENTIRE COOL SEASON)...COMPARED TO OBSERVED 2014-15 VALUES THROUGH MARCH 5TH. .................NORMAL ANNUAL SNOWFALL (INCHES).................... ................NOV...DEC...JAN...FEB...MAR*..APR...TOTAL........... WASHINGTON DC...0.5...2.3...5.6...5.7...1.3...0.0...15.4............ BALTIMORE MD....0.4...3.0...6.8...8.0...1.9...0.0...20.1............ DULLES AIRPORT..0.5...3.5...7.3...7.6...2.8...0.3...22.0............ *NORMAL VALUES FOR THE ENTIRE MONTH OF MARCH ...........OBSERVED 2014-15 SNOWFALL (INCHES, THROUGH MARCH 5TH).... ................NOV...DEC...JAN...FEB...MAR*..TOTAL..(DEPARTURE).... WASHINGTON DC....T.....T....3.6...9.8...4.9...18.3...(+2.9)......... BALTIMORE MD....0.3...0.2...5.9..14.6...6.5...27.5...(+7.4)......... DULLES AIRPORT..1.6....T....8.7..16.1...9.6...36.0...(+14.0)........ *VALUES LISTED ARE TOTALS THROUGH MARCH 5TH...AND ARE ALREADY WELL ABOVE NORMAL FOR THE MONTH. MEANWHILE...AS HAS BEEN THE CASE MANY TIMES IN RECENT MONTHS... RECORD COLD TEMPERATURES ARE IN JEOPARDY AS ANOTHER COLD AIRMASS PIVOTS ACROSS THE REGION DURING THE NEXT 24 HOURS. BELOW IS A LIST OF RECORD DAILY LOW TEMPERATURES FOR MARCH 6TH AND 7TH...AND RECORD DAILY LOW MAXIMUM TEMPERATURES FOR MARCH 6TH. SITE...RECORD MIN 03/06...RECORD LOW MAX 03/06...RECORD MIN 03/07... DCA.....10 F (1988).........21 F (1901)...........13 F (1890)....... BWI.....13 F (1901/1873)....21 F (1901)...........10 F (1960)....... IAD.....15 F (1978).........32 F (2007)...........14 F (1985)....... && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ003>006-011-501>508. VA...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ025>031-040-501-503>508. WV...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ050>053-055-501>506. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST TODAY FOR ANZ532>534-537- 540-541-543. SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ530-531-536-538-539-542. && $$ SYNOPSIS...BAJ NEAR TERM...ADS SHORT TERM...BAJ LONG TERM...BAJ AVIATION...BAJ/ADS MARINE...BAJ/ADS HYDROLOGY...BAJ CLIMATE...DFH

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