Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 300200 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1000 PM EDT WED JUL 29 2015 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA LATE THURSDAY. HIGH PRESSURE WILL BUILD FOR THE WEEKEND AND HOLD THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH THURSDAY/... PCPN CVRG HAS BEEN MUCH SPOTTIER...AND LIGHTER...THAN THIS TIME YDA. WARM LYR BTWN H6-4 ON 00Z LWX RAOB LKLY THE REASON WHY. RDR TRENDS SEEM TO HV BEEN CAPTURED BY THE HRRR QUITE WELL. STORMS E OF THE BLURDG HV DSPTD...W/ ONLY A FEW CELLS IN THE PTMC HIGHLANDS. IF LTST CYCLE OUTPUT VERIFIES...EVEN THIS ACTIVITY WL ERODE BEFORE MIDNGT...W/ NOT MUCH GOING ON TIL NEW CELLS APPROACH THE APLCNS PREDAWN. HV ADAPTED GRIDS TWD THIS DIRECTION...BUT HV HELD ONTO LOW POPS IN THE MTNS. THAT CAN BE REEVALUATED. NOT NEARLY AS MUCH WET GRND AS PAST CPL NGTS. HWVR A FAIR AMT OF CLR SKIES AND DEWPTS IN THE LWR-MID 70S SUGGESTS THERE WL ONCE AGN BE POTL FOR FOG DVLPMNT. HV KEPT IT PATCHY AND NOT DENSE DUE TO REASONS MENTIONED ABV...SITUATED ALONG/W OF BLURDG AS WELL AS ACRS NRN MD. CDFNT CURRENTLY MOVING THROUGH THE MIDWEST WILL ENTER THE FCST AREA AROUND 18Z THU AND SHOULD CLEAR THE FCST AREA BY 03Z FRI. FRONT WILL BE LOSING MUCH OF ITS PUNCH BUT IT APPEARS THERE COULD BE A QUICK BAND OF -SHRA/TSRA RIGHT ALONG OR JUST BEHIND THE FRONT. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... 12Z MODEL SUITE HAS THE COLD FRONT PLACED JUST SOUTHEAST OF THE CWA BY 12Z FRIDAY. ANY LINGERING PCPN WITH THE FRONT SHOULD REMAIN TO THE SOUTH AS THE FRONTAL BOUNDARY STALLS AND EVENTUALLY DISSIPATES OVER THE WEEKEND. SFC HIGH PRESSURE BUILDS IN FROM THE WEST IN THE WAKE. THE REGION WILL REMAIN AT THE SOUTHERN FRINGE OF BROAD CLOSED LOW OVER CANADA...WITH THE SHORTWAVE ENERGY ROUNDING THE LOW REMAINING WELL TO THE NORTH. AS SUCH...EXPECTING DRY WX FRI AND FRI NIGHT. 12Z GFS SUGGESTING LIGHT PCPN OVER NORTHEASTERN AREAS OF THE CWA SAT AFTN WITH A SHORTWAVE JUST TO THE NORTH. WILL KEEP THINGS DRY FOR NOW THOUGH DURING THIS TIME WITH LACK OF SFC FORCING CURRENTLY NOTED. QUICK SHOT OF CAA IN THE WAKE OF THE FRONT ON FRIDAY DROP 850MB TEMPS TO AROUND 15 DEGREES CELSIUS...RESULTING IN HIGHS GENERALLY IN THE 80S. THE COOLER AIRMASS WILL BE SHORT LIVED AS THE HIGH BUILDS IN...WITH 850MB TEMPS REBOUNDING BACK TO NEAR 20 DEGREES CELSIUS BY SAT AFTN. LOWS FRIDAY NEAR NORMAL...WITH HIGHS NEARING 90 ON SATURDAY. DEW PTS IN THE 60S SAT SHOULD KEEP HEAT INDICES WELL BELOW ADVISORY LVLS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... QUIET WEATHER PATTERN FOR SUN INTO MON WITH HIGH PRESS DOMINATING CONDITIONS BEHIND A COLD FRONT. THE FRONT LINGERS OFF THE DELMARVA COAST AS IT WEAKENS... THEREFORE CANNOT RULE OUT SOME SHOWERS TO THE SE AND E OF OUR CWA. SHORTWAVE TROUGH COULD BRING SOME AFTN SHOWERS ON MON AND TUE... BUT CONFIDENCE WITH IT IS LOW ATTM... SO HAVE KEPT LOW POPS. ANOTHER FRONT APPROACHES ON WED INCREASING THE CHANCE OF SHOWERS AND TSTMS FOR THIS DAY. TEMPS WILL NEAR NORMAL SUN AND GRADUALLY INCREASING INTO HE LOW 90S FOR WED. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... VFR CONDS ACRS THE TERMINALS ATTM. SETUP SEEMS FVRBL FOR FOG DVLPMNT ONCE AGN BTWN MIDNGT-DAWN. HWVR NOT AS MUCH WET GRND AS PAST NGTS...WHICH IS COUNTERED BY HIER DEWPTS/LLVL HUMIDITY. UNSURE EXACTLY HOW THESE TWO FACTORS WL BALANCE EACH OTHER. HV OPTED TO KEEP PROLONGED MVFR CONDS OVNGT AT MRB...IFR AT CHO WHERE SHRA WAS RECVD...AND ONLY BRIEF MVFR AT SUNRISE IAD/MTN. DO NOT HV HIGH CONFIDENCE ATTM. CUD SEE FLGT CONDS WORSE THAN FCST BUT WAS HESITANT ON OFFERING UP PROLONGED RESTRICTIONS. FLGT RESTRICTIONS FOR THE MRNG PUSH WL ERODE BY MID MRNG. A CDFNT WL CROSS THE TERMINALS DURING THE AFTN...AFFECTING THAT PUSH AS WELL. SCT-NRMS SHRA/TSRA WL BE FOUND ALONG/AHD OF THE FNT. THINK THERE WL BE SOME DIURNAL STRENGTHENING...AND AM CARRYING VCTS FOR DC/BALT TERMINALS AS A RESULT. WUD NOT COMPLETELY RULE OUT IMPACT AT CHO/MRB BUT PROBABILITY IS LESS. IN THE EVENT OF A DIRECT HIT BRIEF AOB IFR CAN BE ANTICIPATED. TIMING/SPATIAL UNCERTANTIES PRECLUDE CARRYING ANY SPECIFIC MENTION ATTM. WSHFT NEAR 18Z AT MRB...SPREADING EAST TO 21-22Z DCA/BWI. VFR CONDITIONS FRIDAY AND SATURDAY. WINDS GENERALLY 10 KTS OR LESS...SHIFTING FROM THE NW FRIDAY TO A WESTERLY FLOW SAT. && .MARINE... SLY WNDS SUSTAINED 10-15 KT ATTM. HWVR...SLY CHANNELING FCST TNGT OVER THE MD BAY/LWR PTMC. MARGINAL WINDS /MAYBE JUST SHY OF ADVY/ FCST TO CONT THRU THE DAY THU...SPCLY AHD OF CDFNT. SCA ALREADY IN PLACE. LOOKS SOLID TNGT...AND DO NOT HV CONFIDENCE TO REMOVE IT FOR TMRW AT THIS JUNCTURE. BRIEF PERIOD OF SCA GUSTS EARLY FRIDAY MORNING ON THE CHESAPEAKE BAY...WITH ALL WATERS BCMG SUB-SCA BY FRI AFT. SUB-SCA CONDITIONS THEN LASTING INTO THE WEEKEND. && .TIDES/COASTAL FLOODING...
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WATER LVLS RUNNING ABT A HALF FOOT ABV ASTRO NORMALS THIS EVENING. HWVR...THERE IS STRONG CONSENSUS AMONGST WATER LVL MODELS THAT THE UPCOMING HIGH TIDE WL ECLIPSE THE MINOR FLOOD THRESHOLD AT ANNAPOLIS...WHICH HAS BEEN SUPPORTED BY LATEST RUNS. ONLY A SLGT INCREASE IN THE CURRENT DEPARTURE WOULD BE SUFFICIENT TO BEAR THIS OUT. HAVE OPTED TO ISSUE ADVY FOR AA COUNTY. HIGH TIDE AT APAM2 AT 5AM. NO OTHER SITE IN JEOPARDY ATTM...ALTHO BALTIMORE CITY/COUNTY AND WASD2 WL GET AWFULLY CLOSE. THE BALTIMORE HIGH TIDE RUNS BETWEEN 6-8 AM. AT SW DC HIGH TIDE IS APPROX 730 AM. THE PM TIDE WILL BE THE LOWER OF THE TWO ASTRONOMICALLY. NW WINDS THEREAFTER SUGGEST THE UPCOMING TIDE WILL BE THE ONLY ONE TO WATCH CLOSELY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...COASTAL FLOOD ADVISORY FROM 2 AM TO 8 AM EDT THURSDAY FOR MDZ014. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THURSDAY FOR ANZ530>534- 537-539>541-543.
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&& $$ SYNOPSIS...LFR/HTS NEAR TERM...HTS/LFR SHORT TERM...SEARS LONG TERM...IMR AVIATION...HTS/SEARS/IMR MARINE...HTS/SEARS/IMR TIDES/COASTAL FLOODING...HTS

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