Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
000
FXUS61 KLWX 020613
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
113 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/...

HIGH PRES NOSING INTO THE MID ATLC PRNTLY SENTERED 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.

&&

.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 /06Z 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...
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. AN INSTANCE OF SMALL STREAM
FLOODING CANNOT BE RULED OUT THROUGH TONIGHT BUT IS NOT LIKELY. THE
MAIN ISSUE WOULD BE SITUATIONS WHERE PLOWED SNOW IS BLOCKING DRAINS
AND NUISANCE POOLING OF WATER MAY OCCUR. 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.

&&

.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.

&&

$$
PRODUCTS...WOODY/HTS/JCE/LFR


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