Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 020633 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 133 AM EST TUE FEB 2 2016 .SYNOPSIS... HIGH PRESSURE BUILDS INTO THE AREA TONIGHT AND TUESDAY. A STRONGER COLD FRONT WILL MOVE THROUGH THE MID ATLANTIC STATES WEDNESDAY AFTERNOON BRINGING WIDESPREAD RAIN. HIGH PRESSURE BUILDS IN FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TODAY/...
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DON`T WANT THIS TO GET LOST IN THE MULTIPLE SXNS OF THIS DSCN - INTERESTING TO LOOK AT AREA HYDROGRAPHS. STRMS/CRKS SHOWED SHARP RISES DURG MON AFTN BUT ARE NOW FALLING. RVRS ARE NOW ON THE RISE BUT ARE STILL SVRL FT BLO FLD STG. THESE RISES APPEAR TO BE SLOWING. HIGH PRES NOSING INTO THE MID ATLC PRSNTLY CENTERED OVER LK HURON. ATTM A FEW SPOTS REPORTING FOG BUT BY AND LARGE NOT MUCH IN THE WAY OF VSBY RESTRICTIONS. WL KEEP EYES ON THIS THRUT THE NGT. USED AN ENSEMBLE OF MESO GDNC TO POPULATE TEMP/DEWPT GRIDS. BASED ON THAT...ADJUSTED MIN-T FOR THE OVNGT HRS...LWR ACRS N-CENTRL MD /WHERE SKIES SHUD PRTLY CLR AND CAA STRONGEST/ AND SVRL DEGF HIER IN THE SHEN VLY /WHICH CUD BE PLAGUED BY INSULATING LOW CLDS AND FOG/. HIPRES OVER THE GRTLKS WL SETTLE ACRS THE AREA TUE. IT WL BE PROVIDING PT-MOSUN SKIES AND COOLER TEMPS. CLDS WL BE RAPIDLY ADVNCG AHD OF NXT SYSTEM DURING THE AFTN HRS. HWVR...NO WX XPCTD DURING THE DAYTIME HRS.
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&& .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... STRONG WARM AIR ADVECTION PATTERN DEVELOPS LATE TUE NIGHT AHEAD OF STRONG WINTER STORM CURRENTLY AFFECTING THE ROCKIES AND MID- SECTION OF THE COUNTRY. RAIN EXPECTED TO SPREAD NORTHEAST LATE TUE NIGHT AND CONTINUE THROUGH THE DAY WED AS FORCING AND MOISTURE DEEPENS AS SHARP COLD FRONT APPROACHES. A SLIGHT RISK OF A TSRA FOR AREAS ALONG THE I-95 CORRIDOR. PRECIP COULD LINGER OVER SRN MD WED NIGHT AS FRONT SLOWS DOWN AND STALLS ALONG THE ATLC COAST. STORM TOTAL QPF IN THE HALF INCH TO 1.25 INCHES HEAVIEST OVER NORTHEAST MD. NUISANCE FLOODING LIKELY OVER BALTIMORE WHERE STORM DRAINS BLOCKED DUE TO SNOW. SOME RIVER FLOODING LIKELY OVER THE POTOMAC RIVER. REFER TO HYDRO SECTION. && .LONG TERM /THURSDAY THROUGH MONDAY/... SOME UPSLOPE SNOW SHOWERS MAY DEVELOP IN THE MOUNTAINS AND SOME RAIN SHOWERS MAY LINGER IN THE EASTERN PART OF OUR CWA AS COLD FRONT MOVES AWAY ON THU. CONDITIONS SHOULD BE DRYING OUT INTO FRI AND CONTINUE DRY THRU SUN WITH HIGH PRESS CENTERED SOUTH OF THE MID-ATLANTIC AND THEN OFF THE COAST. FOR MON BOTH ECMWF AND GFS BRINGS A COASTAL LOW NEAR US... BUT GFS HAS PRECIP REACHING OUR CWA EARLIER ON MON. WE HAVE TO WATCH THE PROGRESS OF THIS SYSTEM AS P-TYPE MIGHT BE AN ISSUE DEPENDING ON THE TIME IT REACHES US. HIGH TEMPS FOR THIS PERIOD WILL BE IN THE MOSTLY IN THE 40S AND LOW TEMPS IN THE 20S AND LOW 30S. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... ALL SITES PRNTLY VFR. FOG DVLPMNT PSBL AT MRB/CHO BUT ONLY FCSTG MVFR OVNGT. LOTS OF CLOUDS TUE WITH MVFR CIGS POSSIBLE AT KCHO AND KMRB. THEN RAIN AND MVFR/IFR CONDITIONS LATE TUE NIGHT AND WED. VFR SHUD GNLY PREVAIL THU-SAT UNDER BLDG HIPRES. && .MARINE... NLY FLOW ACRS THE WATERS ATTM...GNLY NEAR 10 KT. NO SCA XPCTD. AS HIPRES BLDS N OF THE WATERS TUE...WNDS WL GRDLY VEER ELY...AND EVENTUALLY SELY BY TUE EVNG. SPDS SHUD BE AOB 10 KT. WINDS EXPECTED TO STRENGTHEN WED WITH SOLID SMALL CRAFT CONDITIONS XPCTD. HIPRES WL BLD THEREAFTR. && .HYDROLOGY...
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MON MORNING READING SHOWED ANOTHER HALF INCH OF LIQUID EQUIV LOST BETWEEN FRIDAY AND MONDAY...NOW DOWN TO 1.6 INCHES. STEADY MELTING IS CONTINUING DUE TO THE WARM TEMPERATURES AND MILD DEWPOINTS. THANKS TO THE DRIFTS...THERE ARE SPOTS WITH A LOT OF SNOW COVER AND SNOW WATER...WHILE OTHER SPOTS HAVE GONE TOTALLY BARE. AREAS WHERE THE SNOW DEPTH IS STILL AROUND A FOOT LIKELY HAVE ABOUT 3 INCHES OF WATER IN THAT SNOW. MELTING HAS SHOWN UP ON THE RIVERS IN THE POTOMAC HIGHLANDS AND RAPPAHANNOCK/OCCOQUAN BASINS...NOT SO MUCH YET FURTHER NORTH BUT THERE ARE SIGNS OF THAT BEGINNING TODAY. A SLOW BUT STEADY MELT CONTINUES TUESDAY...BUT NOT AS MUCH AS TODAY SINCE IT WILL BE COOLER. THE PERIOD OF HIGHEST POTENTIAL CONCERN REMAINS WEDNESDAY INTO THURSDAY. TEMPERATURES ARE FORECAST TO WARM INTO THE 60S ALMOST EVERYWHERE EAST OF THE POTOMAC HIGHLANDS WEDNESDAY...WITH RAIN AND LIKELY A MELT OF MOST IF NOT ALL OF THE REMAINING SNOW WATER... ESPECIALLY EAST OF THE BLUE RIDGE. ULTIMATELY...THE FLOOD POTENTIAL WILL BE DEPENDENT ON HOW MUCH SNOW WATER REMAINS BY THEN...AND HOW MUCH RAIN ACTUALLY FALLS. CURRENT EXPECTATIONS ARE FOR A HALF TO THREE-QUARTERS OF AN INCH OF RAIN IN MOST AREAS...POSSIBLY UP TO AN INCH IN NERN MD AND A FEW OTHER LOCALIZED SPOTS. THIS YIELDS POTENTIAL FOR SMALL-STREAM FLOODING WEDNESDAY... ESPECIALLY EAST OF THE BLUE RIDGE...AND URBAN FLOODING WEDNESDAY AFTERNOON ESPECIALLY WHERE DRAINS ARE SNOW-BLOCKED. NOT ENOUGH CONFIDENCE YET TO RAISE AN AREAL FLOOD WATCH. RIVER FLOOD POTENTIAL IS WEDNESDAY NIGHT THROUGH THURSDAY...POSSIBLY LASTING INTO FRIDAY ON THE MAINSTEM POTOMAC. THE HIGHEST POTENTIAL IS GENERALLY BETWEEN SPRINGFIELD AND WASHINGTON DC ON THE POTOMAC... AND THE LARGER TRIBUTARIES THAT FLOW INTO THE POTOMAC...SUCH AS THE OPEQUON AND MONOCACY AND MAINSTEM SHENANDOAH. HOWEVER...IT IS IMPORTANT TO NOTE THAT RIGHT NOW THE MOST LIKELY SCENARIO FOR MOST AREAS WHERE A THREAT EXISTS IS FOR MINOR TO LOW-END MODERATE FLOODING ONLY.
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&& .TIDES/COASTAL FLOODING... WATER LVLS WL BE GRDLY RISING IN ONSHORE FLOW TUE AND SLY FLOW WED. TIDES WL LKLY EXCEED MINOR THRESHOLDS AT HAVRE DE GRACE AND BOWLEYS QUARTERS LATE WED. BALTIMORE AND ANNAPOLIS WL BE THREATENING ACTION STAGE DURING THIS CYCLE AS WELL. WL CONTINUE TO MONITOR. && .CLIMATE... RECORDS HIGHS FOR WED: FEB 3RD IS SORT OF "LOW HANGING FRUIT" AS RECORDS MAXES THAT DAY ARE COLDER THAN SURROUNDING DAYS. DCA: 65 SET IN 1927 BWI: 66 SET IN 1932 IAD: 66 SET IN 1991 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE... HYDROLOGY... TIDES/COASTAL FLOODING... CLIMATE...

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