Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 020018 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 718 PM EST SUN FEB 1 2015 .SYNOPSIS... LOW PRESSURE OVER THE MID MISSISSIPPI VALLEY WILL TRACK ACROSS THE OHIO VALLEY AND INTO PENNSYLVANIA TONIGHT...AND RE-DEVELOP OFF THE NEW JERSEY COAST MONDAY MORNING. CANADIAN HIGH PRESSURE RETURNS TO THE REGION TUESDAY AND SHIFTS OFFSHORE WEDNESDAY. && .NEAR TERM /THROUGH MONDAY/... THE CURRENT SURFACE ANALYSIS INDICATES A DEEPENING 1003MB SURFACE LOW OVER SRN IL...WITH A COLD FRONT TRAILING BACK THROUGH THE LOWER MISSISSIPPI VALLEY...AN A WARM FRONT EXTENDING ENE ACROSS IN/OH. SURFACE HIGH PRESSURE IS NOW WELL OFF THE SOUTHEAST COAST. ALOFT...A VIGOROUS SHORTWAVE TROUGH IS DROPPING THROUGH THE CENTRAL PLAINS RESULTING THE AFOREMENTIONED STRENGTHENING LOW. MID-LEVEL RIDGING STILL PREVAILS LOCALLY AND HENCE A DRY FORECAST WILL BE CONTINUED THROUGH 00Z. DEEPER MOISTURE SHOULD BE SLOW TO REACH E OF THE APPALACHIANS THIS EVENING AS THE SURFACE LOW SHOULD BE OVER SRN IN/OH. THE AIRMASS REMAINS DRY BELOW 800MB EARLY THIS EVENING...SO ONLY A BAND OF 30-40% POPS WILL BE FORECAST FOR EXTREME NRN PORTIONS...BORDERED BY A BAND OF 20% POPS...WITH SUB 15% POPS OVER SE PORTIONS. PARTIAL THICKNESSES SUPPORT RAIN THROUGHOUT THE EVENING...BUT GIVEN THE DRY AIR INITIALLY...THE ONSET OF PCPN COULD BE A BRIEF MIX OF -RA/IP...THOUGH NOT SUBSTANTIAL ENOUGH (SURFACE TEMPERATURES UPPER 30S/LOW 40S) TO INCLUDE IN THE GRIDS. MOISTURE STEADILY INCREASES THROUGH THE NIGHT...WITH LIKELY POPS NW AFTER 03Z...STEADILY INCREASING TO 80-90% FOR ALL AREAS AFTER 09Z. THE SURFACE AIRMASS IS EXPECTED TO MODIFY THROUGH THE NIGHT AS SOUTHERLY FLOW DEVELOPS ACROSS THE REGION DUE TO THE LOW TRACKING N OF THE AREA. LOWS IN THE UPPER 30S/LOW 40S SHOULD OCCUR IN THE EVENING...WITH TEMPERATURES RISING AND RANGING FROM THE UPPER 40S NW...TO LOW/MID 50S SE BY 12Z MONDAY. LIKELY TO CATEGORICAL POPS WILL BE MAINTAINED FOR THE ENTIRE AREA 12-15Z MONDAY...AND IN FAR SE LOCATION THIS SHOULD BE THE PERIOD OF MOST SIGNIFICANT RAINFALL. A QUICK DRYING TREND COMMENCES FROM 15-18Z OVER MOST OF THE AREA...BUT LIKELY TO CATEGORICAL POPS WILL BE MAINTAINED FOR THE ERN THIRD OF THE AREA THROUGH 18Z. TOTAL QPF SHOULD AVERAGE AROUND 0.5 IN...WITH UP TO 0.75 IN ACROSS THE MD ERN SHORE. OTHERWISE...POPS ALONG THE COAST QUICKLY DROP OFF TO 20-30% DURING THE AFTERNOON. THE DAY WILL BEGIN CLOUDY ACROSS THE AREA WITH INTERIOR VA/NC BECOMING PARTLY SUNNY BY AFTERNOON. THE DAY WILL BEGIN WARM...AND CAA WILL LIKELY WAIT UNTIL AFTER SUNSET...SO HIGHS SHOULD RANGE FROM THE UPPER 40S/AROUND 50 F FAR NW...TO 55-60 F ACROSS MOST OF THE AREA. A GUSTY NW WIND WILL DEVELOP AS CLEARING/DRYING ARRIVES MONDAY AFTERNOON...WITH SPEEDS AVERAGING AROUND 20 MPH...WITH GUSTS TO 30-35 MPH. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... DEEP LAYER NW FLOW PREVAILS MONDAY NIGHT...AND BACKS TO WESTERLY TUESDAY. THIS WILL ALLOW SURFACE HIGH PRESSURE (AND ASSOCIATED CAA) TO BUILD INTO THE REGION MONDAY NIGHT...WITH THE HIGH LOCATING ALONG THE COAST BY TUESDAY AFTERNOON. LOWS MONDAY NIGHT SHOULD FALL INTO THE MID TEENS NW...TO LOW 20S SE UNDER A MOSTLY CLEAR SKY. HIGHS TUESDAY WILL BE BELOW NORMAL AND RANGE FROM THE LOW/MID 30S NW...TO LOW 40S SW. A SPLIT FLOW PATTERN WILL PREVAIL TUESDAY NIGHT AND WEDNESDAY...WITH THE MID-ATLANTIC REGION LARGELY SITUATED BETWEEN QUASI-ZONAL NRN STREAM FLOW AND A MOIST SRN STREAM ALONG THE GULF COAST. THIS WILL RESULT IN DRY CONDITIONS...WITH SKY COVER AVERAGING PARTLY CLOUDY ACROSS NRN PORTIONS AND MOSTLY CLEAR/SUNNY ACROSS SRN PORTIONS. SURFACE HIGH PRESSURE MOVES OFFSHORE TUESDAY NIGHT AND WEDNESDAY...WHICH WILL ALLOW TEMPERATURES TO MODERATE. LOWS TUESDAY NIGHT SHOULD AVERAGE 25-30...FOLLOWED BY HIGHS WEDNESDAY IN THE UPPER 40S/AROUND 50 FROM THE NW PIEDMONT TO THE MD ERN SHORE...AND THE LOW/MID 50S ACROSS CENTRAL/SE VA AND NE NC. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
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GFS/ECMWF IN VERY GOOD AGREEMENT WITH REGARD TO OVERALL PATTERN AND TANGIBLE WEATHER DURING THE DAYS 4-7 PERIOD. OVERALL... TEMPERATURES SHOULD BE BELOW NORMAL...WITH NO BIG PRECIP EVENTS IN THE EXTENDED PERIOD. ECMWF HAS TRENDED TOWARD GFS WITH REGARD TO FRONTAL WAVE AND ASSOCIATED COLD FRONTAL PASSAGE ON THURSDAY. EXPECT SOME LIGHT PRECIP...EITHER RAIN AND/OR SNOW TO BE PRODUCED IN ASSOCIATION WITH THE FRONTAL PASSAGE. BEHIND THE FRONT...ANOTHER BRIEF COLD SURGE BUILDS IN FOR THURSDAY NIGHT THROUGH SATURDAY...WITH HIGH PRESSURE IN CONTROL. ANOTHER POLAR/ARCTIC FRONT IS FORECAST TO MOVE SWD INTO THE REGION SATURDAY NIGHT/SUNDAY...WITH A WAVE FORECAST TO DEVELOP SUNDAY NIGHT. ECMWF/GFS DO DIVERGE AT THIS POINT WITH REGARD TO WHERE THE WAVE WILL DEVELOP...AND THEREFORE WHAT TYPE OF PRECIPITATION MIGHT IMPACT THE CWA DURING THAT TIME. GFS IS FURTHER WEST AND WARMER...WITH ECMWF...AS IT HAS FOR THE LAST 1-2 MONTHS...SUGGESTING A WINTER WEATHER EVENT. HAVE GONE IN BETWEEN THE 2 MODELS...WITH CHC OF RAIN AND/OR SNOW...AND CAPPED POPS AT 40 PERCENT.
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&& .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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DRY AIR BELOW 10K FT WILL BE REPLACED BY MOIST CONDITIONS TOWARD MIDNIGHT WITH INCREASING SOUTHERLY FLOW AHEAD OF A FAST MOVING LOW PRESSURE SYSTEM IN THE OHIO VALLEY. PCPN IN SW VA WILL SPREAD EASTWARD AND DEVELOP AT THE TAF SITES DURING THE EARLY MORNING HOURS. IFR CONDITIONS SHOULD HOLD OFF UNTIL THE LOW LEVELS BECOME SATURATED BY THE PCPN. WITH THE AREA BECOMING WARM SECTORED... CONFIDENCE IN IFR IS NOT HIGH...ESPECIALLY AT PHF ORF AND ECG. INCLUDED AT LEAST A FEW HOURS OF IFR AT ALL TAF SITES AS THE NAM BUFR SOUNDINGS WOULD SUGGEST IT WILL OCCUR. WINDS SHIFT TO WESTERLY EARLY MONDAY AFTN AS A COLD FRONT SWEEPS ACROSS THE AREA FROM WEST TO EAST. PCPN ENDS AND CONDITIONS IMPROVE WITH THE FRONTAL PASSAGE. OUTLOOK...HIGH PRESSURE RETURNS TUESDAY. THE NEXT COLD FRONT CROSSES THE REGION WEDNESDAY NIGHT-THURSDAY MORNING WITH A CHC FOR PCPN MAINLY ON THURSDAY.
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&& .MARINE... HAVE MADE ONLY MINOR ADJUSTMENTS TO PREVIOUS FORECAST IN THE SHORT TERM...WHICH WILL BE DOMINATED BY SFC LOW AND ASSOCIATED COLD FRONT MOVING THROUGH THE REGION TONIGHT/MONDAY. WILL UPGRADE TO GLW IN AREAS WHERE A GALE WATCH IS CURRENTLY IN EFFECT. HOWEVER...THERE WILL BE A PROLONGED PERIOD OF SCA CRITERIA WIND BEFORE STRONGEST COLD ADVECTION SURGE MOVES IN LATE MONDAY AFTERNOON/MONDAY EVENING. WINDS DROP OFF QUICKLY ON TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION. HIGH MOVES OFFSHORE TUESDAY NIGHT...WITH NEXT FRONT FORECAST TO CROSS THE REGION THURSDAY AND THURSDAY EVENING. GFS/ECMWF HAVE SOME INTO BETTER AGREEMENT WITH THE EVOLUTION OF THIS FRONT ACROSS THE AREA...AND HAVE FOLLOWED THEM CLOSELY. WINDS EXPECTED TO BE WEAKER AHEAD OF THIS FRONT...REMAINING BELOW SCA CRITERIA. BEHIND THE FRONT...ANOTHER GOOD COLD SURGE SHOULD SEND WINDS WELL INTO SCA CRITERIA THURSDAY INTO THURSDAY NIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST MONDAY FOR ANZ630>638. GALE WARNING FROM 6 PM MONDAY TO 6 AM EST TUESDAY FOR ANZ630>632-634-650-652-654-656-658. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EST MONDAY FOR ANZ650- 652-654-656-658. && $$ SYNOPSIS...AJZ/LKB NEAR TERM...AJZ/LKB SHORT TERM...AJZ/LKB LONG TERM...WRS AVIATION...LSA MARINE...WRS

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