Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 220116 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 916 PM EDT MON JUL 21 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN ALONG THE EASTERN SEABOARD THROUGH TUESDAY. TEMPERATURES WILL SLOWLY RISE THROUGH WEDNESDAY AHEAD OF A COLD FRONT EXPECTED TO MOVE INTO THE AREA THURSDAY. HIGH PRESSURE IS EXPECTED TO RETURN TO THE MID ATLANTIC STATES TO END THE WORKWEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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HIPRES REMAINS FROM THE NEW ENGLND CST DWN THRU THE MID ATLC... KEEPING SELY LLVL FLOW ACROSS THE CWA. SHRA THAT HV DVLPD LT TDA HV PRIMARILY BEEN ALNG THE RDG LINE. NOW THAT DIURNAL HTG HAS BEEN LOST...XPCT THESE TO WANE. LWX 00Z RAOB DEPICT RELATIVELY AMPLE MSTR THRU H6. GIVEN THE ONSHORE MSTR FEED AND LGT WNDS...HV A GOOD SCENARIO FOR LOW CLDS/FOG TO DVLP. THOSE WL BE THE PRIMARY OVNGT CONCERNS...AND ARE DEPICTED QUITE WELL BY GOING FCST. WL ADJUST W/ LTST GDNC BLENDED IN...HITTING UPON LTST TRENDS.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... FLAT RIDGE BUILDS IN FOR TUESDAY. DAY LIKELY STARTS OUT WITH PLENTY OF CLOUDS BUT SOME PEEKS OF SUNSHINE SHOULD OCCUR IN THE AFTERNOON. RIDGE MAY HELP LIMIT CONVECTION...BUT WITH BETTER MOISTURE/INSTABILITY THAN RECENT DAYS CAN/T RULE OUT A FEW SHOWERS/THUNDERSTORMS DURING THE AFTERNOON/EVENING MAINLY NEAR THE HIGHER TERRAIN. HEIGHTS START TO DECREASE FOR WEDNESDAY. DESPITE THIS...A SHIFT TO A SOUTHWEST WIND AND SOME SUNSHINE SHOULD SUPPORT WARMER TEMPERATURES LIKELY AOA 90 DEG EAST OF THE BLUE RIDGE. MODELS ALSO HINT AT THE PRESENCE OF A PRE-FRONTAL TROUGH...THUS EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE CWA BY AFTERNOON. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HEAVY SHOWERS AND STRONG TO POSSIBLY SEVERE THUNDERSTORMS MAY DEVELOP DURING THE DAY THURSDAY DUE TO A COMBINATION OF UPPER ENERGY...A COLD FRONT AND DAYTIME HEATING. THE STRONGEST THUNDERSTORMS COULD PRODUCE DAMAGING WINDS AND LOCALLY HEAVY RAIN. HIGH CAPE AND LOW TO MODERATE SHEAR COULD LEAD TO THE DAMAGING WINDS...WHILE PRECIPITABLE WATER VALUES OF AROUND 2 INCHES COULD INDICATE HEAVY RAIN WOULD BE A THREAT FROM THE STORMS. AS OF NOW...TIMING OF THE HEAVIEST ACTIVITY APPEARS TO BE THURSDAY AFTERNOON AND EVENING. A SURFACE COLD FRONT WILL PUSH THROUGH OUR REGION THURSDAY NIGHT TO ALLOW FOR A RIDGE OF HIGH PRESSURE TO BUILD IN FROM THE NORTHWEST. THIS FRONT HAS THE POTENTIAL TO STALL NEAR THE VIRGINIA AND NORTH CAROLINA BORDER THURSDAY NIGHT INTO FRIDAY...THUS MAYBE KEEPING A SLIGHT CHANCE OF RAIN SHOWERS ACROSS THE SOUTHERN TWO-THIRDS OF THE CWA WITH A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE VIRGINIA PIEDMONT AND MAIN STEM CHESAPEAKE BAY. HIGH PRESSURE SHOULD GRADUALLY PUSH THE FRONT FARTHER SOUTH TO ALLOW COOLER AND DRIER AIR TO MOVE IN ACROSS THE CWA FRIDAY AFTERNOON THROUGH MIDDAY SATURDAY. THE HIGH IS EXPECTED TO MOVE OFFSHORE SATURDAY AFTERNOON AND SATURDAY NIGHT. AN ONSHORE FLOW DEVELOP DURING THE PERIOD...AIDING IN AN INCREASE IN LOW LEVEL MOISTURE. GIVEN THE UNCERTAINTY OF THE POSITION OF THE HIGH...NEAR LONG ISLAND OR THE TIDEWATER OF VIRGINIA...WE LEFT A CHANCE OF RAIN SHOWERS SATURDAY AND A SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM SATURDAY NIGHT. DESPITE THE HIGH BEING THE FAVORITE...BOTH THE EURO AND GFS INDICATE A FEW RIPPLES IN THE UPPER LEVEL FLOW THAT MAY INDICATE A WEAK DISTURBANCE OR TWO MAY FIND ITS WAY ACROSS OUR CWA...HENCE THE CHANCE OF A SHOWER OR STORM. SUNDAY AND MONDAY WILL BE A PRECURSOR OF AN ACTIVE MIDWEEK OF SHOWERS AND THUNDERSTORMS AS A STRONGER UPPER LEVEL STORM SYSTEM PIVOTS ACROSS THE GREAT LAKES. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/...
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HIPRES OFF THE MID ATLC/NEW ENGLAND COAST. GIVEN ONSHORE FLOW... XPCT LOW CLDS/FOG TO DVLP. PRVS TAFS ALREADY HAD MVFR/IFR RESTRICTIONS. FOR 00Z CYCLE...EXPANDED UPON THAT A BIT AREALLY. SOME GDNC SUGGESTING LIFR /OR VLIFR/. DID NOT TAKE THAT STEP YET...THO ITS CERTAINLY CONCEIVABLE. VFR RETURNING BY TUE AFTN. ONCE AGN...SCT SHRA PSBL...BUT NOT AT A LVL WORTHY OF TAF INCLUSION AT THIS JUNCTURE. AFTERNOON/EVENING THUNDERSTORMS ARE POSSIBLE ON WEDNESDAY. IFR OR LIFR CONDITIONS ARE POSSIBLE AT ANY OF THE TERMINALS THURSDAY AS LOCALLY HEAVY RAINFALL AND GUSTY WINDS ACCOMPANY THE SHOWERS AND THUNDERSTORMS.
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&& .MARINE...
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HIGH PRESSURE ALONG THE COAST KEEPING A SOUTHEAST FLOW IN PLACE. WINDS TURN MORE TO THE SOUTH TONIGHT INTO TUESDAY...CHANNELLING LIKELY TO PROMOTE WINDS INCREASING CLOSER TO 15 KT UP THE MAIN CHANNEL OF THE BAY. CHANNELLING COULD RESULT IN MARGINAL SCA CONDITIONS UP THE BAY BY WEDNESDAY EVENING. NO MARINE HAZARDS EXPECTED THURSDAY THROUGH FRIDAY...EXCEPT FOR POSSIBLE GUSTY WINDS IN THUNDERSTORMS THURSDAY.
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&& .TIDES/COASTAL FLOODING...
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ANOMALIES CONTINUE TO BE AROUND 1 FT ABOVE NORMAL ON THE WESTERN SHORE OF THE CHESAPEAKE BAY THIS EVENING. THESE MAY EVEN MOVE UPWARD A LITTLE THROUGH TONIGHT GIVEN SOUTHEAST FLOW. GIVEN CURRENT ANOMALIES...THIS WILL PUT WATER LEVELS ABOVE MINOR FLOOD AT ANNAPOLIS AND RIGHT NEAR MINOR FLOOD AT BALTIMORE. CBOFS HAS BOTH LOCATIONS ABOVE MINOR FLOOD DURING HIGH TIDE AS WELL. A COASTAL FLOOD ADVISORY REMAINS IN EFFECT FOR ANNE ARUNDEL AND SOUTHERN BALTIMORE COUNTIES FOR TONIGHT/S HIGH TIDE. WILL HAVE TO WATCH OTHER COUNTIES ON THE WESTERN SHORE OF THE BAY IF ANOMALIES INCREASE FURTHER. SW DC WILL BE CLOSE. RISK OF MINOR TIDAL FLOODING MAY OCCUR AGAIN DURING HIGH TIDE TUESDAY NIGHT WITH SOUTHERLY FLOW IN PLACE.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...COASTAL FLOOD ADVISORY FROM 1 AM TO 6 AM EDT TUESDAY FOR MDZ011-014. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BPP NEAR TERM...HTS SHORT TERM...BPP LONG TERM...KLW AVIATION...HTS/BPP/KLW MARINE...HTS/BPP/KLW TIDES/COASTAL FLOODING...BPP/HTS

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