Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 022033 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 333 PM EST MON MAR 2 2015 .SYNOPSIS...
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HIGH PRESSURE THEN WILL BUILD ACROSS THE AREA TONIGHT. A WARM FRONT WILL PUSH THROUGH THE AREA TUESDAY NIGHT. A STRONG COLD FRONT WILL APPROACH THE REGION LATE WEDNESDAY FOLLOWED BY COLD HIGH PRESSURE FOR THURSDAY INTO THE WEEKEND.
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&& .NEAR TERM /THROUGH TUESDAY/...
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HIGH PRESSURE WILL BUILD INTO THE MIDDLE ATLANTIC REGION TONIGHT. WINDS WILL DIMINISH BY SUNSET AND WITH MOSTLY CLEAR SKIES...TEMPERATURES WILL FALL OFF QUICKLY AND BOTTOM OUT IN THE LOWER 20S IN MOST LOCATIONS EXCEPT TEENS OVER THE NORMALLY COLDER AREAS WEST OF THE BLUE RIDGE. CLOUDS WILL BE ON THE INCREASE FROM WEST TO EAST BY EARLY TUESDAY MORNING AS THE NEXT WEATHER SYSTEM APPROACHES FROM THE WEST. LIGHT PRECIPITATION IS EXPECTED TO BEGIN FIRST OVER THE WESTERN SLOPES OF THE ALLEGHENY FRONT THEN SPREADING EAST ACROSS THE REMAINDER OF THE FORECAST AREA MID TO LATE MORNING. PROFILES INDICATE THERE IS ENOUGH COLD AIR FOR PRECIPITATION TO START AS A MIXTURE OF SNOW AND SLEET BUT A FAIRLY QUICK TRANSITION TO SLEET AND FREEZING RAIN IS EXPECTED BY MIDDAY TO EARLY AFTERNOON. SNOWFALL AMOUNTS WILL BE LIGHT. CAD SITUATION EXPECTED ONCE AGAIN WITH COLD HIGH TO THE NORTH AND EAST HELPING TO TRAP COLDER AIR IN THE LOWER LEVELS. LIGHT FREEZING RAIN/FREEZING DRIZZLE WILL BECOME THE MAIN P-TYPE BY AFTERNOON WITH A FEW HUNDREDTHS TO ONE TENTH OF AN INCH OF ICE ACCRETION EXPECTED. SURFACE TEMPERATURES WILL BE COLD ENOUGH FOR SOME SLIPPERY TRAVEL TO DEVELOP FOR THE AFTERNOON AND EVENING COMMUTE. A WINTER WEATHER ADVISORY WILL BE ISSUED TO COVER THIS THREAT. WARMER AIR WILL GRADUALLY FILTER IN FROM SOUTH TO NORTH AS SOUTHERLY WINDS INCREASE DURING THE LATE AFTERNOON AND EARLY EVENING. RAIN WILL BECOME MORE LIKELY OVER CENTRAL AND SOUTHERN LOCATIONS. LIGHT FREEZING RAIN WILL LIKELY HOLD ON LONGER FOR THE FAR NORTH AND WEST SUBURBS OF BALTIMORE AND WASHINGTON DC INTO THE EVENING. HIGH TEMPERATURES TOMORROW WILL ONLY RISE INTO THE 30S IN MOST LOCATIONS.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
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COLD AIR MAY BE LINGERING INTO THE ELY EVNG N OF THE PTMC RIVER TUE EVNG...OTRW WAA WL MAKE ITS WAY TO THE SFC. SHUD HV WARMING TEMPS THRUT THE NGT. THEREFORE...WL BE RUNNING W/ A PTYPE OF RA... W/ JUST A LITTLE LINGERING FZRA TO THE N. THE MAIN PTYPE ISSUE FOR OVNGT TUE INTO WED WL BE RA. A SOLID PLUME OF MSTR WL BE CHANNELED EWD FM THE WRN GLFMEX AHD OF AN APPROACHING CDFNT. AM GOING W/ QPF ARND A HALF INCH...CLOSER TO AN INCH FOR THE MTNS. MORE ON THIS IN THE HYDRO SECTION BELOW. CFP WL COME LT IN THE DAY. WE WL BE STARTING FM A BASE IN THE UPR 40S NORTH TO UPR 50S SOUTH /BLENDED NEWER GDNC INTO THE ENSEMBLE MAXT FCST/ SO EVEN AFTER FROPA...PCPN WL STILL BE RAIN. PROBLEM IS...SFC TEMPS WL KEEP DROPPING THRU THE AFTN-EVNG WHILE THE PLUME OF MSTR CONTS TO STREAM EWD ABV IT. THAT WUD SUPPORT PCPN CHGG OVER TO SNW /OR PERHAPS SLEET/ WED NGT. QSTNS REVOLVE ARND THE TIMING OF THAT TRANSITION ALONG W/ HOW MUCH MSTR WL BE AVBL AT THAT TIME. AN UPR JET WL BE SUPPORTIVE OF PCPN GENERATION...AS WE WL BE IN THE RRQ. AT THIS TIME...IT SEEMS APPARENT THAT THERE WL BE MEASUREABLE SNOW WED NGT INTO THU MRNG. IT CUD BE MORE THAN JUST A LTL. HV THIS IN THE HWO ATTM. REFER TO OUR PROBABLISTIC DATA VIA OUR WEBSITE FOR THE RANGE OF POSSIBILITIES. HV SNOW TAPERING OFF DURING THE DAY ON THU. DOUBT THERE WL BE MUCH OF A TEMP RISE.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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AFTER A FEW BUSY WX DAYS...HIGH PRESSURE SETTLES INTO THE REGION OVERNIGHT THURSDAY. EXPECT LIGHT WINDS WITH CLEARING SKIES...LEADING TO STRONG RADIATIONAL COOLING AND VERY COLD TEMPERATURES...ESPECIALLY IF THERE IS SNOW COVER FROM THE THURSDAY SYSTEM. HIGH TEMPERATURES WILL REMAIN NEAR FREEZING FRIDAY DESPITE THE RETURN OF WAA. AFTER ANOTHER COLD NIGHT FRIDAY...TEMPERATURES BEGIN TO REBOUND SATURDAY AND EVEN MORE SUNDAY. HOWEVER...THEY WILL REMAIN IN THE MID/UPPER 40S...WHICH IS BELOW AVERAGE FOR THIS TIME OF YEAR. AT THIS POINT LEFT WEEKEND PRECIP FREE. BUT...RECENT MODEL RUNS APPEAR TO HAVE A SYSTEM DEVELOPING IN THE DEEP SOUTH AND PERHAPS BEGINNING TO IMPACT OUR AREA ON SUNDAY. WOULD LIKE TO SEE MORE RUN TO RUN CONSISTENCY BEFORE INTRODUCING POPS.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/...
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VFR EXPECTED THROUGH 12Z TUESDAY. LIGHT PRECIPITATION WILL MOVE IN FROM WEST TO EAST BY MID TO LATE MORNING. HAVE INTRODUCED LIGHT SNOW/SLEET MIXTURE AT MOST TERMINALS AROUND MIDDAY BUT EXPECT FREEZING RAIN TO BECOME THE MAIN P-TYPE BY AFTERNOON AND EVENING. THE PRECIPITATION MAY CHANGE TO ALL RAIN CENTRAL AND SOUTH WITH LIGHT FREEZING RAIN/FREEZING DRIZZLE HOLDING ON LONGER NEAR KBWI. MVFR TO IFR FLGT CONDS SHUD BE WIDESPREAD TUE NGT THRU THU. MAINLY RA TUE NGT AND WED. SNOW SHUD BE THE PRIMARY PTYPE WED NGT INTO THU. DEPENDING UPON TIMING...LIFR PSBL. AT THIS POINT NOT EXPECTING ANY AVIATION CONCERNS FROM THURSDAY NIGHT THROUGH SUNDAY.
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&& .MARINE...
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SOLID SCA CONDITIONS OCCURRING THIS AFTERNOON WILL DIMINISH BY SUNSET. ADDITIONAL SMALL CRAFT CONDITIONS COULD DEVELOP TUESDAY NIGHT. VISIBILITY WILL BE REDUCED IN FROZEN PRECIPITATION TUESDAY AFTERNOON INTO TUESDAY NIGHT. THERE IS THE POTENTIAL FOR A BRIEF PERIOD OF SCA THURSDAY AFTERNOON AND NIGHT BEFORE WINDS SUBSIDE. AFTER THIS NOT EXPECTING MARINE CONCERNS THROUGH SUNDAY.
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&& .HYDROLOGY... WE HAVE BEEN ADVERTISING THE POTENTIAL OF MIDWEEK FLOODING IN THE HAZARDOUS WEATHER OUTLOOK. LIQUID PRECIP FCST FROM WPC PUTS MUCH OF THE FCST AREA IN A MINIMA FOR AMOUNTS...AROUND AN INCH OR LESS IN MANY AREAS. WITH TEMPERATURES EXPECTED TO RISE INTO THE 50S ON WEDNESDAY...THERE WILL BE SOME...POSSIBLY A LOT OF...MELTING OF THE EXISTING SNOWPACK...WHICH COMPUTER MODELS AND OBSERVATIONS INDICATE CONTAINS ANYWHERE FROM 3/4 INCH TO 2 INCHES OF SNOW WATER EQUIVALENT. THIS COMBINATION MAY LEAD TO MINOR FLOODING AS THE RAIN FALLS ON WEDNESDAY. ALTHOUGH RIVER ICE IS NOT ESPECIALLY THICK...IT WILL HAVE TO BE MONITORED FOR POTENTIAL ROLE IN AFFECTING RUNOFF. ALSO...PLOWED SNOW IS LIKELY COVERING SOME OF THE DRAINS OUT THERE...WHICH COULD CAUSE MORE POOR DRAINAGE FLOODING THAN WOULD OTHERWISE USUALLY BE EXPECTED. WORTH NOTING...CURRENT FORECAST RAIN TOTALS ARE ON THE LOWER SIDE OF THE ENSEMBLE SUITES OF THE GEFS AND SREF. PLEASE CONTINUE TO MONITOR THE FORECAST FOR UPDATES AS THE EVENT GETS CLOSER.&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...WINTER WEATHER ADVISORY FROM 9 AM TO 10 PM EST TUESDAY FOR DCZ001. MD...WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST TUESDAY FOR MDZ501-502. WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM EST TUESDAY FOR MDZ003. WINTER WEATHER ADVISORY FROM 9 AM TO 7 PM EST TUESDAY FOR MDZ016>018. WINTER WEATHER ADVISORY FROM 9 AM TO 10 PM EST TUESDAY FOR MDZ004>006-011-013-014-503>508. VA...WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST TUESDAY FOR VAZ025>031-503-504-507-508. WINTER WEATHER ADVISORY FROM 9 AM TO 7 PM EST TUESDAY FOR VAZ036>040-050>052-055>057-501-502. WINTER WEATHER ADVISORY FROM 9 AM TO 10 PM EST TUESDAY FOR VAZ053-054-505-506. WV...WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST TUESDAY FOR WVZ050-055-501>506. WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM EST TUESDAY FOR WVZ051>053. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530>543.
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&& $$ SYNOPSIS...KRW NEAR TERM...KRW SHORT TERM...HTS LONG TERM...MSE AVIATION...KRW/HTS/MSE MARINE...KRW/HTS/MSE HYDROLOGY...JE

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