Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 281914 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 314 PM EDT SAT MAR 28 2015 .SYNOPSIS...
-- Changed Discussion --
AN UPPER-LEVEL TROUGH WILL MOVE ACROSS THE EASTERN UNITED STATES TONIGHT. HIGH PRESSURE WILL BUILD OVERHEAD ON SUNDAY. A COLD FRONT WILL DROP THROUGH THE AREA ON MONDAY...WITH ANOTHER COLD FRONT ARRIVING ON WEDNESDAY.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
LTST WATER VAPOR IMAGERY DEPICTS A SHARP UPR TROF AXIS ACRS THE NERN CONUS TAFTN. EMBEDDED W/IN THIS AXIS IS A S/WV ENTERING WRN PA. A CONCENTRATION OF CLDS EVIDENT ON VSBL SATPIX...AND IT APPEARS AS THO THERE ARE ACCOMPANYING FLURRIES ON RGNL RADARS. 12Z NAM/GFS IN GOOD AGREEMENT SWINGING THIS FEATURE ACRS MD LT TAFTN INTO ELY THIS EVNG. WHERE DIFFS LAY RELATE TO THE AMT OF ASSOCD MSTR. ITS TRUE THAT IN THE WAKE OF THE MRNG TROF DEWPTS HV DROPPED...AND HV VALUES NEAR 10F ACRS A SIZEABLE PORTION OF THE CWFA ATTM. THAT WL DO A GOOD JOB EATING AWAY AT ANY PCPN THAT ATTEMPTS TO FALL. HWVR...PVA IMPRESSIVE AND ITS TIMED IN SYNCH WITH BEST DAYTIME HEATING. THUS WOULD BE INCLINED TO BELIEVE THAT SOMETHING WL REACH THE GRND. THE MORE GENEROUS GFS QPF FIELDS KEEPING TRUE TO ITS TENDENCY TO BE WETTER...WHICH THIS MRNG PROVED TO BE THE BETTER FCST. STATISTICAL GDNC ON THE OTHER HAND WUD TEND TO WASH OUT SUCH SMALL SCALE FEATURES. THEREFORE...NEW DATABASE GRIDS ALIGNED WITH THIS MORE AGGRESSIVE SOLN. TEMPS TAFTN WARMER THAN THE MRNG ROUND...BUT BY NO MEANS WUD IT BE CONSIDERED WARM-- JUST ABOUT EVERYWHERE TRAPPED IN THE 30S. THEREFORE ANY FALLING PCPN WUD LIKELY BE PARTIALLY IF NOT COMPLETELY FROZEN. TIME OF YEAR AND TEMP OF AMS ALOFT SUGGEST GRAUPEL A CONSIDERATION. WL STICK W/ SHSN OR SHRASN FOR SIMPLICITY. BEST TIMING WOULD BE 20-00Z BASED ON MEAN VORT POSN. AFTR SUNSET...POTL SHUD WANE. IN THE WAKE OF THE VORT...EXPECT MEAN LYR RH TO THIN...WHICH WHEN FACTORED W/ LOSS OF DIURNAL CLDS AND NVA...CLDS SHUD RAPIDLY DECREASE. STILL A DECENT P-GRAD SO WINDS SHUD BECOME LESS BUT WL STILL BE A FACTOR. CONSIDERING IMPACT OF CAA AND CURRENT TEMPS... WENT ON THE COOL SIDE OF MOS MEAN EVEN W/O GOOD DCPLG. THUS MIN-T IN THE TEENS COMMONPLACE BLURDG WWD. WL BE UNDER TRANSITORY SFC HIPRES SUNDAY W/ BLDG HGTS ALOFT. THAT SHUD BE A FVRBL COMBO...MOSUN SKIES AND WARMER TEMPS. MOS MEAN NOT FAR OFF FM PRVS FCST...SO A BLEND WAS TAKEN. MAXT MAY EXCEED 50F IN OUR VA CNTYS...STILL MORE THAN 10 DEGF BLO AVG BUT 10+ DEGF WARMER THAN TDA. IN ADDITION...WNDS ARND 5 KT WUD MEAN NOT MUCH OF A WIND CHILL.
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
AFTER YET ANOTHER REMINDER WINTER HASN`T COMPLETELY LEFT...THE START OF THE WORK WEEK WILL HAVE MORE OF A SPRING-LIKE REBOUND. LOWS SUN NIGHT INTO MON MORNING WILL BE COLD...NEAR FREEZING IN MOST AREAS BRIEFLY - AND ALSO STARTING OFF CLOUDY W/ AN UPPER WAVE PASSAGE. A BRIEF PERIOD OF UPSLOPE PRECIP...AND SOME LIGHT SNOW AND/OR RAIN SHOWERS FOR PORTIONS OF THE SRN FRINGE OF THE AREA. GOOD GUIDANCE AGREEMENT THAT THE APLCNS EFFICIENTLY DISPERSE MUCH OF THE PRECIP AS THE UPPER WAVE AND SFC COLD FRONT QUICKLY PASSES OVERHEAD. SOME WEAK LLJ DYNAMICS AND SOME LIMITED THE WINDS WILL THEN KICK-IN SHORTLY AFTER SUNRISE...LOW LEVEL - BUT INCREASING - MOISTURE SHOULD ALSO ALLOW FOR SOME PRECIP DEVELOP ACROSS OUR SRN FRINGE BRIEFLY EARLY MON. A LIGHT AND BRIEF RAIN/SNOW MIX POSSIBLE OVER SRN MD/DELMARVA BEFORE DAWN...THEN THIS ACTIVITY QUICKLY MOVES OFF THE COAST. IN ITS WAKE WILL BE CLEARING SKIES OVER THE AREA AND A BREEZY WLY WIND THAT WILL KEEP THE HIGHER TERRAIN COOLER BUT THE DOWNSLOPING EFFECT IN THE VLYS/LOWLANDS WILL HELP HIGH TEMPS REACH THE M-U50S BY AFTN. WINDS WILL GUST IN THE 20-30KT RANGE ACROSS THE AREA...ESPEC ALONG THE MASON-DIXON LINE AND ACROSS THE HIGHER TERRAIN. NOT ANTICIPATING WIND ADVISORY CONDS BUT IT COULD BE WARRANTED FOR HIGHER TERRAIN. MON NIGHT...TEMPS WILL AGAIN DROP TOWARD THE FREEZING MARK...EVEN W/ A RELATIVELY HIGHER DEWPOINT FIELD ACROSS THE REGION. AS WINDS DROP OFF FROM THE MONDAY COLD FRONTAL PASSAGE...TUE WILL START OFF MUCH MORE CALM BUT STILL COLD. TEMPS WILL QUICKLY CLIMB BACK THRU THE 40S AND 50S ON THE WAY TO HIGHS IN NEAR 60F BEFORE YET ANOTHER UPPER WAVE PASSAGE. ODDLY THE 12Z VERSIONS OF THE EURO AND GFS TRADED SOLUTIONS FROM THEIR 06Z RUNS. THE LATEST GFS TOOK THE MINOR UPPER WAVE ELONGATED MORE LATITUDINALLY AND MADE IT THE FURTHER NORTH COMPACT LOW SPREADING DIRECTLY OVER PA AND TOUCHING OUR NRN FRINGE. THE 12Z EURO IS THE OPPOSITE. THEIR ALGORITHMS ALSO MAKE A DECENT PERCENTAGE OF THE MODEL PRECIP INTO SNOW...ESPEC OVER THE NRN REACHES OF THE PRECIP BATCH. THE TROUBLE W/ THE STRONGER OF THE SOLUTIONS - WHICH WOULD BE THE POTENT AND MORE COMPACT SYSTEM TO THE NORTH IS THAT IT WOULD ILLICIT A STRONGER WAA REGION OUT AHEAD OF THE SYSTEM. THE WARMER AIR ENTRAINED INTO THE PORTION OF THE SYSTEM SPREADING ACROSS OUR REGION WOULD HAVE A LOWER POTENTIAL FOR FROZEN PRECIP W/ HIGHS REACHING THE 50S/L60S JUST AHEAD OF THE SYSTEM. NOT AN INTENSE TEMP PLUNGE EXPECTED W/ THIS FEATURE EITHER WAY...W/ TEMPS DROPPING AT AN AVERAGE PACE INTO THE U30S/L40S. THE ADVECTION PATTERN ALSO NOT PARTICULARLY STRONG ACCORDING TO THESE SAME MODELS...WHICH KEEPS THE SFC WINDS FAIRLY LIGHT THROUGHOUT THIS EPISODE.
-- End Changed Discussion --
&& .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
-- Changed Discussion --
A FEW RAIN SHOWERS COULD LINGER ALONG THE MASON DIXON REGION TUESDAY NIGHT AS A COLD FRONT WORKS ITS WAY SOUTHWARD AND HIGH PRESSURE BUILDS SOUTHEASTWARD FROM THE GREAT LAKES REGION. LOW TEMPERATURES WILL BE MAINLY IN THE UPPER 30S TO NEAR 40...NEAR NORMAL FOR EARLY APRIL. THE HIGH PRESSURE WILL BRING DRY CONDITIONS AND NEAR NORMAL TEMPERATURES TO THE REGION WEDNESDAY. EXPECT HIGH TEMPERATURES TO BE NEAR 60 TO THE MIDDLE 60S. AS THE HIGH MOVES TO THE EAST COAST AND OFFSHORE WEDNESDAY NIGHT...A SOUTHERLY FLOW WILL DEVELOP AND INCREASE DURING THE DAY THURSDAY AHEAD OF AN APPROACHING COLD FRONT. LOW TEMPERATURES SHOULD REACH THE MIDDLE 40S WEDNESDAY NIGHT AS HIGHS ARE EXPECTED TO APPROACH 70 DEGREES ACROSS MUCH OF THE REGION THURSDAY. A COLD FRONT SHOULD PUSH ACROSS THE LOWER GREAT LAKES THURSDAY BEFORE SLOWING DOWN AND DRAGGING ACROSS THE MID ATLANTIC REGION THURSDAY NIGHT AND FRIDAY. THIS FRONT WILL BE THE FOCAL ZONE OF DEVELOPING RAIN SHOWERS AND PERHAPS A RUMBLE OF THUNDER OR TWO LATE THURSDAY THROUGH FRIDAY. TEMPERATURES SHOULD REMAIN MILD THURSDAY NIGHT AND FRIDAY WITH HIGHS REACHING THE MIDDLE 60S FRIDAY. BY FRIDAY NIGHT AND POSSIBLY AS LATE AS SATURDAY AFTERNOON...A LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP ALONG THE COLD FRONT AND PUSH ACROSS THE REGION...BRINGING PROLONGED CHANCES OF RAIN SHOWERS OR EVEN A THUNDERSTORM. TIMING IS UNCERTAIN AS TO THIS LOW`S DEVELOPMENT AND ITS LOCATION OR PROGRESS...NONETHELESS...THE RAIN CHANCES LINGER ONCE AGAIN ACROSS THE MID ATLANTIC.
-- End Changed Discussion --
&& .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR CONDS WL GENERALLY PREVAIL THRU TMRW. HWVR...CANNOT GUARANTEE A DRY FCST. THERE MAY BE A FEW SHOWERS...OF RAIN OR SNOW OR EVEN GRAUPEL...LATE THIS AFTN TO NEAR SUNSET SPCLY NEAR BWI/MTN. HWVR CONFIDENCE AND AREAL CVRG PRECLUDE ANY RESTRICTIONS IN TAFS. DID PLACE WX IN TAF FOR MTN/BWI NEAR TIME OF MOST LKLY OCCURENCE...20- 23Z. ANY RESTRICTIONS WUD BE BRIEF AND LIMITED...MOST LKLY NO LWR THAN MVFR. WINDS WL BE THE LARGER SCALE ISSUE...WITH NW WINDS 15 KT GUSTING UP TO 25-30 KT. THE GUSTS WL SUBSIDE SOMEWHAT THIS EVNG...BUT WL STILL HV 10-15 KT WINDS INTO TMRW. DURING THE DAY SUNDAY WINDS WL SUBSIDE TO LESS THAN 10 KT AND VEERING SW. FEW IF ANY CLDS XPCTD. A FAST-MOVING COLD FRONT WILL SLIDE THRU EARLY MON MRNG...W/ LITTLE IF ANY PRECIP BUT A BRIEF PERIOD OF OVC MID CLOUDS THAT BREAK UP AND MOVE E QUICKLY AFTER SUNRISE. SFC AND BOUNDARY LAYER WINDS EXPECTED IN THE 30-40KT RANGE W/ SOME 20-25KT GUSTS AT THE SFC DURING THE DAYTIME HRS. MVFR CONDITIONS POSSIBLE AT MTN AND BWI TERMINALS TUESDAY NIGHT DUE TO LINGERING RAIN SHOWERS NEAR A FRONT...OTHERWISE...VFR CONDITIONS ELSEWHERE TUESDAY NIGHT AND WEDNESDAY. WINDS LIGHT AND VARIABLE TUESDAY NIGHT BECOMING NORTHWEST AND GUSTING TO 15 KNOTS WEDNESDAY.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SOLID SCA CONDS ATTM CONTG THRU THIS EVNG. WINDS WL BE SLOWLY SUBSIDING OVNGT AND SUNDAY MRNG. HV SCALED BACK SCA AT MIDNGT FOR THE MID-UPR PTMC. CONTD THE REST INTO SUN MRNG...AND CONTD MID BAY INTO SUNDAY AFTN. PASSING HIPRES WL BE RESPONSIBLE FOR DIMINISHING WINDS DURING THE DAY. A COLD FRONT CROSSES OVER THE AREA EARLY MON MRNG...W/ SCA CONDS POSSIBLE OVERNIGHT. BEHIND THE FRONT...WEST WINDS WILL AGAIN PICK UP INTO SOLID SCA RANGES AND POSSIBLE GALES FOR THE DAYTIME HRS MON. WINDS WILL GRADUALLY SUBSIDE OVERNIGHT INTO TUE. ANOTHER COLD FRONT WILL CROSS THE REGION LATE TUE...W/ A PERIOD OF LOW-END SCA GUSTS POSSIBLE. NO MARINE HAZARDS EXPECTED TUESDAY NIGHT AND WEDNESDAY. WINDS MAY GUST TO 15 KNOTS WEDNESDAY.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
WATER LVLS AS LOW AS A FOOT BELOW ASTRO PREDICTIONS IN THE NRN BAY AND 1.5 FT IN THE UPPER TIDAL POTOMAC ATTM. THIS NEGATIVE DEPARTURE WILL ONLY INCREASE AS STRONG NW WINDS RESULT IN BLOW-OUT CONDS.
-- End Changed Discussion --
&& .CLIMATE...
-- Changed Discussion --
TEMPERATURES SUNDAY MORNING MAY APPROACH THE RECORD LOWS FOR THE DATE. CURRENTLY THE FORECAST LOWS ARE ABOVE THESE RECORDS...ASIDE FROM DULLES. IF THE LOW DROPS TO 21 OR LESS AT DULLES IT WOULD BE THE COLDEST SO LATE IN THE SEASON SINCE 1987...AND IF THE LOW DROPS TO 24 OR LESS AT BWI IT WOULD BE THE COLDEST SO LATE IN THE SEASON SINCE 1985. SITE...3/29 RECORD MIN T... DCA......18 (1923)......... BWI......18 (1923)......... IAD......20 (1982).........
-- End Changed Discussion --
&& .EQUIPMENT...
-- Changed Discussion --
NWR PIKESVILLE HAS RETURNED TO SERVICE AFTER TOWER WORK TODAY.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT SUNDAY FOR ANZ530>532- 537>540-542. SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR ANZ533-534-541- 543. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ535-536.
-- End Changed Discussion --
&& $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...GMS LONG TERM...KLW AVIATION...HTS/GMS/KLW MARINE...HTS/GMS/KLW TIDES/COASTAL FLOODING...HTS CLIMATE...DFH/JE/HTS EQUIPMENT...HTS

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.