Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 311836 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 236 PM EDT FRI OCT 31 2014 .SYNOPSIS...
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LOW PRESSURE DESCENDING FROM THE GREAT LAKES WILL CROSS THE CAROLINAS SATURDAY BEFORE STRENGTHENING OFFSHORE WHILE HEADING TOWARDS CAPE COD SUNDAY. HIGH PRESSURE WILL RETURN TO THE AREA MONDAY AND TUESDAY FOLLOWED BY A COLD FRONT DURING MIDWEEK.
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&& .NEAR TERM /TONIGHT/...
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W.V. STLT IMGRY SHOWS SHORT WV HAS PUSHED INTO SRN LAKE MI. THIS WILL DIVE ACROSS SC SAT AS UPPER LEVEL PATTERN UNDERGOES SUBSTANTIAL AMPLIFICATION W/ A RDG OVR THE CENTRAL PART OF THE COUNTRY AND A LARGE TROF DVLPG OFFSHORE AS THE NORTHERN AND SOUTHERN STREAMS PHASE. WITH THIS SOUTHWARD TRAJECTORY...FORCING WILL BE FOCUSED OVER THE MOUNTAINS FOR THE FIRST STAGE OF THIS SYSTEM. RAIN SHOWERS ARE POSSIBLE THIS AFTN/TNGT IN THE HIGHLANDS. E OF THE MTNS XPCTD TO BE DRY TNGT. TEMPS IN THE L50S OVR MUCH OF THE AREA FOR TRICK OR TREATING. LOWS WL BE IN THE 40S XCPT 30S IN THE HIGHLANDS.
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&& .SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
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UPR VORT/SHORT WV OVR ERN TN SAT MRNG...MOVG E OF THE SC CST DURG THE AFTN. THIS WL MAKE THE HIGHLANDS THE ONLY AREA IN THE FCST AREA W/ THE PSBLTY OF SEEING SNOWFALL..BUT THE 1000-850MD TCHKNS`S AREN`T THAT LOW: ~1320M. THIS MEANS THE ATMOSPHERIC COLUMN JUST ISN`T THAT COLD...AND ANY PCPN THAT FALLS IN THE FRZN VARIETY WL BE VERY DEPENDENT ON ELEVATION. DURG SAT ACCUMULATIONS WOULD BE SLUSHY AND MINOR. BLV THAT THERE WL BE A PD OF RA E OF THE MTNS JUST ABT EVERYWHERE SAT. HIGHS RANGING FM THE L50S E OF I-95 TO THE U30S IN THE HIGHLANDS. BY SAT NGT...S/WV ENERGY WUD HV SHIFTED OFF THE CST...INDUCING CYCLOGENESIS NE OF CAPE HATTERAS. IN TERMS OF PCPN E OF THE APLCHNS...THAT PRETTY MUCH WL MARK THE END...AS DRIER AIR WL WORK IN ON THE NW SIDE OF THE CYCLONE. WINDS MAY BE THE BIGGEST IMPACT...BUT THE NOCTURNAL TIMING MAY PREVENT THE FULL 30-40 KT AVBL H9-8 FM MIXING DOWN. WL BE KEEPING GUSTS 25-30 MPH. ACRS THE MTNS...THE AMS WL BE COOLING SUFFICIENTLY FOR SOME SNOW. HWVR...THE BEST DYNAMIC COOLING WL PASS S OF AREA. THIS LEAVES ONLY A MARGINALLY FVRBL AMS W/ WARM GRND. SNOW TOTALS 1-2" IN THE HIGHER ELEVS. IT IS NOT OUT OF THE QSTN THAT ACCUMS COULD BE ENUF TO REACH ADVSRY LVL...BUT THIS IS NOT A SLAM DUNK AND WL LV THIS TO BE DECIDED LATER. LOWS SAT NGT RANGE FM THE M20S IN THE MTNS TO THE L40S ALONG THE BAY.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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BLV WINDS MAY END UP BEING THE BIGGEST STORY FM THE UPCOMING SYSTEM. SOME SNOW FLAKES COULD CONTINUE TO FALL FOR A COUPLE OF HOURS AFTER SUNRISE ALONG THE ALLEGHENY FRONT...BUT ALL OF THE PRECIP WILL BE WRAPPED UP ACROSS THE AREA BY MID-MORNING SUNDAY. THE STORY WILL THEN BE THE COLD AND WIND. A 100+ KT JET CENTERED AROUND 20000 FT WILL PASS OVERHEAD SUNDAY. EXPECT A DECENT AMOUNT OF THESE WINDS TO MIX DOWN TO THE SURFACE...WITH FREQUENT GUSTS IN THE 30 TO 40 KT RANGE POSSIBLE FOR THE HIGHER ELEVATIONS AND OVER THE BAY...AND GUSTS OF 20 TO 30 KTS POSSIBLE ELSEWHERE...DURING THE DAY SUNDAY. DEEP LAYER NORTHWESTERLY FLOW WITH A FETCH WELL UP INTO EASTERN CANADA WILL BRING SEASONABLY COOL AIR TO THE MID-ATLANTIC. HIGHS SUNDAY WILL BE AROUND 50...WHICH IS ABOUT 10 TO 15 DEGREES BELOW NORMAL...THOUGH STILL A COUPLE OF DEGREES ABOVE RECORD LOW MAXIMUM TEMPS. SUNDAY NIGHT WILL SEE THE COLDEST TEMPS OF THE FALL SO FAR...WITH FREEZING AND SUBFREEZING TEMPERATURES EXPECTED FOR MOST OF THE CWA AS HIGH PRESSURE SETTLES INTO THE AREA. WIND SPEEDS WILL ALSO BE ON THE DECLINE SUNDAY NIGHT DUE TO THE DECREASING PRESSURE GRADIENT AS THE HIGH PRESSURE CENTER APPROACHES. HIGH PRESSURE WILL SETTLE ALONG THE SOUTHEAST COAST FOR THE FIRST PART OF THE WORKWEEK AND TEMPS WILL MODERATE TOWARD NORMAL AS LIGHT RETURN FLOW FILLS IN. HIGHS TUESDAY AND WEDNESDAY SHOULD BE WELL INTO THE 60S WITH PLENTY OF SUNSHINE. A COLD FRONT MAY APPROACH THE AREA WEDNESDAY NIGHT AND THURSDAY. THIS DOES NOT APPEAR TO BE A STRONG COLD FRONT...SO CONFIDENCE IS LOW IN PRECIPITATION COVERAGE AT THIS POINT. OPERATIONAL ECMWF ACTUALLY KEEPS US MOSTLY DRY WHILE GFS BRINGS IN SOME LIGHT RAIN. OVERALL HAVE LOW END CHANCE POPS IN THE FORECAST WITH RAIN AS THE ONLY EXPECTED P-TYPE DUE TO WARM LOW LEVEL TEMPS. HIGH PRESSURE SHOULD BUILD BACK IN BY THE END OF NEXT WORKWEEK.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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SKIES HV GONE OVC OVR MUCH OF THE AREA AS LOW PRES OVR MI ROTATES MOISTURE INTO THE MID ATLC. CIGS ARE PRSNTLY VFR...BUT THESE ARE XPCTD TO SLOWLY LWR OVRNGT. MVFR CONDS XPCTD SAT. LOW PRESSURE STRENGTHENS OFF THE COAST SAT. NRLY WINDS WILL GUST UP TO 20-25 KT. WINDS WL PROVIDE PRIMARY IMPACT SAT NGT-SUN...AS AN ELEVATED CORE OF 40+ KT WNDS CROSS TERMINALS. THE LLJ WL RESIDE ABT 2K FT ABV SFC. SHUD HV 25-30KT GUSTS IN NW FLOW AT GRND LVL...MAYBE A LTL HIER THAN THAT SUN MRNG-MIDDAY. ANY CIGS WUD BE MVFR-VFR SAT NGT AND SHUD CLR BY/SOON AFTR SUNRISE SUN MRNG. VFR SUN AFTN INTO TUE.
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&& .MARINE...
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NE WINDS WL BECOME MORE NRLY TNGT BUT RMN UNDER SCA CONDITIONS THRU TNGT AS A LOW PRESSURE SYSTEM PASSES SW OF THE AREA. WITH THE STRENGTHENING LOW MOVING OFF THE COAST ON SATURDAY...SMALL CRAFT CONDITIONS WILL BE MET WITH NORTHERLY WINDS GUSTING TO AROUND 30 KT. WE HV ISSUED A GALE WRNG FOR SAT NGT. A GALE WARNING WILL LIKELY BE NEEDED FOR PORTIONS OF THE WATER DURING THE DAY SUNDAY AND POTENTIALLY INTO SUNDAY EVENING. A SMALL CRAFT ADVISORY MAY BE NEEDED INTO EARLY SUNDAY MORNING.
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&& .TIDES/COASTAL FLOODING...
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BLOWOUT CONDITIONS ARE XCTD SAT AFTERNOON THROUGH SUNDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 AM TO 8 PM EDT SATURDAY FOR ANZ530>543. GALE WARNING FROM 8 PM EDT SATURDAY TO 6 AM EST SUNDAY FOR ANZ530>543.
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&& $$ PRODUCTS...WOODY!/CEB

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