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 271438 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1038 AM EDT SAT JUN 27 2015 .SYNOPSIS... A WARM FRONT OVER NORTH CAROLINA WILL LIFT NORTH INTO THE AREA THIS AFTERNOON. A COLD FRONT WILL PASS THROUGH THE AREA TONIGHT AFTER MIDNIGHT. HIGH PRESSURE WILL BE IN PLACE FOR MONDAY WITH WEAK COLD FRONT TUESDAY NIGHT. LOW PRESSURE IS EXPECTED TO CROSS THE REGION FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 14Z...LOW PRESSURE OVER OHIO AND THE WARM FRONT OVER NC. LOW INTENSIFIES AS IT DRIFTS NE ACROSS OH TODAY...STALLING TONIGHT OVER NERN OH AS THE STORM BECOMES VERTICALLY STACKED. THE WARM FRONT WILL WILL LIFT NORTH INTO THE DC METRO THIS AFTERNOON AND MAY STALL THERE UNTIL EITHER LIFTING JUST BEFORE THE COLD FRONT ARRIVES LATE TONIGHT...OR JUST CONTINUE TO DRIFT NORTH THROUGH THE EVENING. FIRST ROUND OF ROUND OF RAIN IS PUSHING THROUGH THE BALT-WASH METRO AREA. THE NEXT ACTIVITY WILL BE PRE-FRONTAL COMING FROM THE SW FROM WV AS SEEN IN ACTIVITY OVER THE CNTRL SHEN VLY. A FEW WAVES OF THIS ACTIVITY WILL RESULT IN INCREASINGLY SEVERE TSTMS...PARTICULARLY AS THE WARM FRONT LIFTS INTO THE AREA. PREVIOUS...AFTER 18Z...IT APPEARS SOME AREAS WILL BE ABLE TO GET INTO THE WARM SECTOR WITH AN INCREASING RISK OF SEVERE T-STORMS INCLUDING TORNADOES. GUIDANCE SHOWS DIFFERENT SOLUTIONS WITH RESPECT TO WARM FRONTAL POSITION WITH GFS SHOWING AREAS ALONG AND EAST OF I-95 TO THE PA AND DE BORDER BREAKING OUT INTO THE WARM SECTOR WHILE THE ECMWF IS MORE CONSERVATIVE ONLY INDICATING AREAS FROM DC EAST TO ANNAPOLIS AND POINTS SOUTH GETTING INTO THE WARM SECTOR. A FEW HP SUPERCELLS APPEAR LIKELY GIVEN 0-6KM SHEAR VALUES OF 30 M/S AND 0-3 KM SRH OF 350 M^2/S^2 WITH AN ATTENDANT RISK OF A COUPLE OF TORNADOES AND VERY HEAVY RAINFALL AND FLASH FLOODING. WITH RESPECT TO FLOODING POTENTIAL...GUIDANCE STILL SHOWS AREAS NORTH AND EAST OF THE POTOMAC RIVER DOWN TO ALEXANDRIA RECEIVING THE HEAVIEST RAINFALL IN THE ORDER OF 1 TO 3 INCHES. CDFNT WILL CLEAR THE CHES BAY JUST AFTER 06Z SUN ENDING THE SVR AND FLOODING THREAT. && .SHORT TERM /SUNDAY/... WRAP AROUND MOISTURE AROUND DEEP SFC CYCLONE OVER THE NORTHEAST AND CYCLONIC FLOW WILL MAINTAIN BKN SKIES WITH THE RISK OF A FEW SHOWERS MAINLY NORTHERN AND FAR WESTERN AREAS. BREEZY AND MUCH COOLER THAN NORMAL WITH TEMPS STRUGGLING TO HIT 80F. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... ANY WRAP-AROUND/ UPSLOPE RAIN SHOWERS IN THE POTOMAC HIGHLANDS WILL END SUNDAY EVENING AS THE STRONG LOW PRESSURE SYSTEM PULLS AWAY FROM NEW ENGLAND. A MUCH COOLER AND DRIER AIRMASS WILL BE FOUND IN ITS WAKE...WHICH WILL ALLOW TEMPERATURES TO DROP INTO THE 50S EXCEPT IN THE URBAN AREAS AND COASTAL PLAIN. MONDAY WILL BE A DRY DAY AS SHORTWAVE RIDGING QUICKLY SLIDES ACROSS THE AREA. TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL. NEXT SHORTWAVE TROUGH WILL BE MOVING INTO THE GREAT LAKES MONDAY NIGHT...LEADING TO AT THE VERY LEAST INCREASING CLOUDS. SOME DIFFERENCES ON HOW MUCH PRECIP MAKES IT INTO OUR AREA...BUT HAVE CONFINED POPS WEST OF I-81 OVERNIGHT. WITH THE TROUGH AXIS APPROACHING TUESDAY...EXPECT AT LEAST SCATTERED CONVECTION ACROSS THE AREA. SFC LOW LIFTS NORTH INTO QUEBEC ON WED...WITH THE TRAILING COLD FRONT BECOMING PARALLEL TO THE UPPER FLOW AND STALLING OVER THE MID-ATLANTIC. THIS LEADS TO AN UNSETTLED PATTERN IN WHICH THE DETAILS ARE A BIT MURKY. THE 00Z GFS PUSHES THE FRONT SOUTH BY FRIDAY...WHILE THE ECMWF KEEPS IT NEARBY AND CONTINUES CHANCES FOR CONVECTION. TEMPERATURES ARE EXPECTED TO REMAIN WITHIN SEVERAL DEGREES OF NORMAL THROUGH THE UPCOMING WEEK. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... BRIEF PERIOD OF MVFR ACROSS THE TERMINALS BECOMING IFR EITHER FROM VSBYS IN RAIN OR LOW CEILINGS. TSTMS EXPECTED WITH A RISK OF DAMAGING WINDS ACROSS THE AREA. CIGS IMPROVE TO VFR AFTER 09Z SUN AFTER A COLD FRONT SHIFTS WIND WEST. WEST WIND GUSTS 20 TO 25 KT SUNDAY IN VFR CONDS. VFR CONDITIONS EXPECTED SUNDAY NIGHT THROUGH MONDAY NIGHT. SLOW MOVING COLD FRONT APPROACHES TUESDAY AND THEN MAKES LITTLE PROGRESS. THUNDERSTORMS WITH SUB-VFR CONDITIONS WILL BE POSSIBLE TUESDAY...WITH WEDNESDAY/S THUNDERSTORM FORECAST A LITTLE LESS CERTAIN. ALSO SOUTHERLY WINDS MAY GUST ABOVE 20 KT ON TUESDAY. && .MARINE... GUSTY SERLY FLOW TODAY WITH SCA IN PLACE FOR ALL WATERS. HEAVY AND GUSTY THUNDERSTORMS WITH A WATER SPOUT THREAT LATE THIS AFTERNOON INTO THE OVERNIGHT AS A WARM FRONT LIFTS ACROSS THE WATERS AND AHEAD OF A COLD FRONT THAT CROSSES LATE TONIGHT. WINDS SHIFT TO WSW TONIGHT (WITH A BRIEF LULL)...THEN BECOME REMAIN GUSTY THROUGH SUN. SCA THROUGH SUN. GUSTY WESTERLY WINDS WILL CONTINUE INTO SUNDAY EVENING AND THE SCA WILL LIKELY NEED TO BE EXTENDED. WINDS WILL DIMINISH ON MONDAY AS HIGH PRESSURE QUICKLY PASSES BY. SOUTHERLY FLOW WILL BECOME ESTABLISHED MONDAY NIGHT...AND CHANNELING OVER THE BAY IS POSSIBLE. SCA IS MORE LIKELY ACROSS ALL WATERS ON TUESDAY AHEAD OF A COLD FRONT. SCATTERED THUNDERSTORMS MAY ALSO DEVELOP. WINDS WILL DIMINISH TUESDAY NIGHT INTO WEDNESDAY AS THE LOW PRESSURE CENTER MOVES INTO CANADA. && .TIDES/COASTAL FLOODING... WIDESPREAD MINOR COASTAL FLOODING EXPECTED TONIGHT ON THE PREFERRED HIGH TIDE. SELY FLOW 15 TO 25 KT HAS RAISED WATER LEVELS ARE AROUND 1.2 FT ABOVE ASTRO TIDE ON THE BAY LATE THIS MORNING. WATER LEVELS WILL CONTINUE TO RISE THROUGH THIS EVENING AHEAD OF A COLD FRONT. AFTERNOON HIGH TIDE WILL SEE MINOR COASTAL FLOODING ONLY AT THE PARTICULARLY SENSITIVE SITE OF ANNAPOLIS WHERE AN ADVISORY IS IN EFFECT UNTIL 4PM. WIDESPREAD MINOR COASTAL FLOODING TONIGHT ON THE PREFERRED HIGH TIDE. WILL ISSUE THE ADVISORY AROUND MIDDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR DCZ001. MD...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR MDZ003>006-011-013- 014-016-501>508. COASTAL FLOOD ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR MDZ014. VA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR VAZ025>031-036>040- 050>056-501>508. WV...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WVZ050>053-055- 501>506. MARINE...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR ANZ535-538. SMALL CRAFT ADVISORY UNTIL 9 PM EDT SUNDAY FOR ANZ530>543. && $$ SYNOPSIS...BAJ/LFR NEAR TERM...BAJ/LFR SHORT TERM...LFR LONG TERM...ADS AVIATION...BAJ/ADS/LFR MARINE...BAJ/ADS/LFR TIDES/COASTAL FLOODING...BAJ

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