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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 301346 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 946 AM EDT SAT AUG 30 2014 .SYNOPSIS... HIGH PRESSURE OFF CAPE COD WILL MOVE SOUTHEAST AND BECOME A BERMUDA HIGH FOR THE HOLIDAY WEEKEND AND THROUGH TUESDAY. A COLD FRONT WILL CROSS THE AREA TUESDAY NIGHT. HIGH PRESSURE WILL FOLLOW FOR THE SECOND HALF OF THE WEEK. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
-- Changed Discussion --
SFC HIPRES OFF ACK THIS MRNG. SLY FLOW ACRS THE MID ATLC...WHICH WL PREVAIL THRU THE DAY. ONSHORE FLOW ARND THE PERIPHERY OF THE HIGH HAS BROUGHT LOW DECK CLDS TO POINTS ALONG/E OF THE BLURDG. FCST CHALLENGE WL REVOLVE ARND WHEN THESE CLDS SCT OUT. LWX 12Z RAOB DEPICTS A STBL/CAPPED ATM. MEANWHILE...PBZ RAOB CONTAINS SOME INSTBY ABV SFC INVSN. INSOLATION ACRS THE MTNS...AIDED BY A WK SFC WMFNT...WL BE THE SOURCES FOR CNVCTV INITIATION TAFTN. NOT TOO IMPRESSIVE...BUT ENUF TO KEEP 20-30 POPS FOR TRRN CIRCULATIONS. THINK THE INFLUENCE OF THE WMFNT WL BE MORE TWD A RIBBON OF BKN CLDS. IN THE EAST...THAT/LL BE A PD OF CLDS REPLACING THE CURRENT CLDS. MAXT WL BE KEPT LWR...AND PCPN SHUDNT BE A CONCERN.
-- End Changed Discussion --
&& .SHORT TERM /7 PM THIS EVENING THROUGH MONDAY NIGHT/...
-- Changed Discussion --
IT/LL BE A WARMER AND MORE HUMID NGT TNGT AS SWLY FLOW BECOMES MORE ENTRENCHED ACRS AREA. FED BY THIS WARMTH/INSTBY...TSRA MAY ATTEMPT TO EMERGE OFF MTNS TWD EVNG...BUT WL BE FIGHTING THE LOSS OF DIURNAL HEATING. HV LEADING EDGE /SCHC/ TO CATOCTINS- CENTRL SHEN VLY. IT SHUD REMAIN RAIN-FREE EAST OF THERE. HV DECREASING TRENDS AFTR MIDNGT. SUNDAY FEATURES THE BEST CHANCE OF STORMS OVER THE HOLIDAY WEEKEND RIGHT NOW. LEE TROF IN PLACE...WEAK SHORT WAVE MOVING IN...HI TEMPS IN THE MID 80S TO AROUND 90...SOME WEAK JET DIVERGENCE AT HIGHER LEVELS...ALL OF THESE ARE INGREDIENTS FOR SOME STORMS. THE MOST DISTURBING PARAMETER IS THE GFS FORECASTING PRECIPITABLE WATER TO BE OVER 2 INCHES OVER A WIDE AREA. WHILE THERE IS ENOUGH WIND IN THE ATMOSPHERE TO KEEP STORMS MOVING...COULD BE ISOLATED AREAS OF FLASH FLOODING WITH THAT MUCH MOISTURE. WILL MAINTAIN MENTION IN HAZARDOUS WEATHER OUTLOOK FOR SUNDAY INTO SUNDAY NIGHT. MONDAY WILL STILL BE WARM AND HUMID...BUT PRECIPITABLE WATERS FALL...LEE TROF SLACKENS...AND SHORT WAVE MOVES OUT. FOR THESE REASONS EXPECT LESSER CHANCES OF STORMS MONDAY THAN SUNDAY FOR ANY ONE SPOT. STILL SCT STORMS EXPECTED THOUGH.
-- End Changed Discussion --
&& .LONG TERM /TUESDAY THROUGH FRIDAY/... ELEVATED HEAT INDICES WILL CONTINUE TO BE A CONCERN HEADING INTO MIDDLE OF NEXT WEEK. DEWPOINTS WILL CONTINUE HOVERING AROUND THE 70F DEG MARK...WHICH IS PLENTY HUMID IN COMBINATION W/ DAILY HIGHS POKING ABOVE 90F DEG. FROM LATE MON INTO TUE...A POTENT AND LARGE- SCALE LOW PRESSURE SYSTEM WILL SWINGING THRU THE GREAT LAKES/UPPER MIDWEST. THE PARENT LOW WILL BE WELL TO THE NORTH...PULLING UP INTO THE SRN HUDSON BAY REGION/QUEBEC. THE DYNAMICS OF THIS SYSTEM WILL HEAD DUE EAST...STRADDLING THE US/CANADA BORDER AND TAKING THE HEAVIEST PRECIP ALONG W/ IT - WELL TO OUR NORTH TUE INTO WED. SOME RESIDUAL SHOWERS HANGING AROUND THE COASTAL ZONES OVER TO THE I-95 CORRIDOR FROM LATE MON NIGHT WILL BE DISSIPATING EARLY TUE...AS HIGH PRES BUILDS IN FROM THE SRN APLCNS. THIS HIGH...IN CONCERT W/ THE OFFSHORE AND LARGER BERMUDA HIGH WILL AGAIN PRESS THE HEAT/HUMIDITY UP INTO THE MID ATLC. THE RELATIVE LACK OF ORGANIZED FORCING ACROSS THE REGION WILL KEEP SKIES GENERALLY CLEAR TUE WHICH WILL BE LITTLE RELIEF IN TERMS OF THE HOT CONDITIONS. MORE DRY AND HOT WEATHER TO CARRY US THRU THE SECOND HALF OF THE WEEK...THOUGH TUE MAY BE THE WARMEST DAY - ALBEIT ONLY BY COUPLE OF DEG. LATE TUE EVE...THE TAIL END OF THE COLD FRONT FROM THE GREAT LAKES LOW WILL LIKELY CROSS THE REGION. THE FRONT WILL CARRY SOME SCATTERED SHOWERS AND TSTMS. GOOD LOW LEVEL LAPSE RATES DURING PEAK HEATING AND MODEST INSTABILITY WILL MAKE FOR AT LEAST A HANDFUL OF STRONG TSTMS...MORE IF OUTFLOW-DRIVEN. ZONAL UPPER FLOW OVER THE NRN HALF OF THE CONUS FOR THE SECOND HALF OF WEEK WILL ESSENTIALLY HOLD OUR WARM/HUMID AIRMASS IN PLACE. WHILE THE COLD FRONT KICKS OFF PRECIP A COUPLE OF STATES TO OUR SOUTH...THE MID-ATLC WILL BE MAINLY DRY TO CLOSE OUT THE WEEK UNTIL AN UPPER SHORTWAVE ARRIVES FROM THE WEST LIKELY NEXT WEEKEND. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
MVFR CIGS HOLDING ON AT IAD /BORDERLINE...OVC030/ AND CHO /SOLIDLY...OVC010-015/. CIGS SHUD LIFT WITH DIURNAL HEATING. SO...FLGT RESTRICTIONS SHUD EASE AT IAD AOB 16Z AND AOB 18Z AT CHO. WITH INCREASING LOW LVL HUMIDITY...OVERNIGHT FOG WILL BE AN INCREASING ISSUE. EXPECT SOME MVFR FOG FOR DULLES AND AREAS WEST TNGT. OUTLOOK... TARGETED IFR POSSIBLE AT TIMES WITH ANY THUNDERSTORMS SUN- MON. ONLY BRIEF AND SHORT-LIVED PERIODS OF PRECIP POSSIBLE TUE- WED...BUT MAINLY DRY AND MOSTLY SUNNY EACH DAY.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SLY FLOW ACRS THE MARINE AREA THRU THE WKND. WITH DIURNAL MIXING... INCRSD SPDS IN THE AFTN-EVE. SCA IN EFFECT LT TAFTN-TNGT FOR BAY SANDY PT-SMITH PT DUE TO POTL OF 20 KT GUSTS. IT/LL BE A SIMLR SITUATION SUNDAY. IN ADDITION...POTL TSRA WUD PROVIDE STRONGER WIND GUSTS. OFFSHORE HIGH PRES WILL CONTINUE TO STEER WARM/HUMID AIR UP ACROSS THE ERN SEABOARD. ONLY MINOR PERIODS OF SLY CHANNELING AND/OR SCA CONDITIONS POSSIBLE INTO THE MIDDLE OF NEXT WEEK. A WEAK COLD FRONT WILL LIKELY CROSS THE WATERS BY LATE TUE/EARLY WED. A FEW TSTMS POSSIBLE W/ THIS FEATURE. HIGH PRES THEN BUILDS IN THROUGH THE REST OF THE WEEK.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
TIDAL DEPARTURES HV JUMPED UP SINCE YDA...AND NOW ARE HOVERING BTWN A 1/2 FT AND 1 FT ABV NORMAL. WINDS SHOULD REMAIN SLY...SO ANTICIPATE ADDTL INCREASES THROUGH THE WKND. CANNOT DISCOUNT POSSIBLE ISSUES AT SENSITIVE LOCATIONS BEFORE THE WKND IS OVER.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EDT SUNDAY FOR ANZ532>534.
-- End Changed Discussion --
&& $$ SYNOPSIS...CAS NEAR TERM...HTS SHORT TERM...HTS/CAS LONG TERM...CAS/GMS AVIATION...HTS/CAS/GMS MARINE...HTS/CAS/GMS TIDES/COASTAL FLOODING...HTS

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