Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 300752 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 352 AM EDT SUN AUG 30 2015 .SYNOPSIS... HIGH PRESSURE REMAINS OVER THE REGION THROUGH THE MIDDLE OF THE WEEK AND THEN WEAKENS THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... SYNOPTICALLY...NOT MUCH HAS CHANGED IN THE PAST 24 HRS. HIPRES RDG STILL RESIDES OVER THE ERN SEABOARD...PERHAPS A LTL BIT FURTHER EAST THAN SAT MRNG. ALOFT THERE IS A S/SWLY DRIFT...WHICH IS EVIDENT FM MID-UPR LVL CLDS STREAMING INTO VA. THE LAST FEW FRAMES OF STLT LOOP SUGGESTS THAT THERE MAY BE SOME THINNING TO THE MSTR...AND AM STILL HOPEFUL THAT WE/LL BE MOCLR AT SUNRISE. THESE CLDS /AND THE FACT THAT WE HVNT FULLY DCPLD/ HV INTERFERED W/ FOG FORMATION...AND DO NOT ANTICIPATE MUCH AT DAWN. NOT ONLY IS THERE HIPRES AT THE SFC...BUT THIS RDG EXTENDS UP THRU H5...PARKED OFF HSE. THUS...SUBSIDENCE SHUD LIMIT INSTBY FOR MUCH OF THE CWFA. LWR HGTS ACRS THE APLCNS COMBINED W/ TRRN CIRCULATIONS SUGGEST THAT IF SHRA/TSRA DVLP THE MTNS WL BE THE LOCATION. ATTM THREAT LOOKS A LTL LESS THAN IT DID FM YDA/S CYCLE...AND HV TRIMMED THE AREAL CVRG THRU DUSK. THE THREAT NEVER WAS ALL THAT GREAT...20- 30 POPS AT BEST. ONE DIFF OVER SAT WL BE THE SKYCOVER. THINK THERE WL BE A FAIR AMT OF MID-UPR LVL CLDCVR SPREADINGA CRS AREA...MAINLY DURING THE AFTN. IN SPITE OF THIS...AMS WL BE CAPABLE OF SUPPORTING MAXT A CPL DEGF WARMER. METRO BALT/DC/F-BURG SHUD HV A 90 DEGF DAY. OVER THE BLURDG/SHEN VLY/PTMC HIGHLANDS...MID-UPR 80S WL BE COMMON. SWLY FLOW WL SUPPORT DEWPT ADVCTN TO THE MID 60S-- STILL NOT BAD BUT A LTL BIT STICKY. PVA APPROACHES AREA TNGT FM THE SW AS A SUBTLE SFC BNDRY DROPS SWD FM THE GRTLKS. THESE TWO FEATURES SUGGEST THAT NOT ONLY WL POPS LINGER PAST SUNSET...BUT THE CHC WL SPREAD EAST FM THE MTNS TWD I- 95. LIKE THE AFTN...PROBS NOT HIGH /20-30 PCT/ AND QPF LVLS LOW. CLDS MORE CERTAIN THAN PCPN. A MAJORITY OF THE TIME CUD BE JUST MOCLDY W/O ANY RAIN. WHAT DOES FALLS MAY BE NOT MUCH MORE THAN SPRNKLS...SPCLY DURING THE OVNGT HRS. HARD TO PROVIDE SPECIFIC TIMING OTHER THAN HOLDING BACK ACRS THE DC/BALT BURBS THRU MID EVNG. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... DETAIL ISSUES LINGER INTO MON...AS THE SFC BNDRY DSPTS IN/NEAR NRN CWFA AND PVA/MSTR CONTS TO OVERSPREAD AREA FM THE SW. NEED TO KEEP BKN CLDS AND LOW END POPS IN THE FCST FOR MUCH OF THE DAY DUE TO THIS WEAK/DISORGANIZED FORCING...ALTHO CONFIDENCE IN GETTING WET QUITE LOW. H5 TROF AXIS WL PROGRESS E OF AREA BY LT DAY...AND WL OFFER UP CLRG DURING THE MID-LT AFTN INTO ELY EVNG IN ITS WAKE. SHUD BE MOCLR BY OVNGT MON INTO ELY TUE. AM NOT GOING QUITE A WARM FOR MAXT MON DUE TO CLDS AND PCPN CHCS. HWVR...AS DEWPTS THREATEN TO REACH THE UPR 60S...CANT SAY THE SAME FOR MIN-T FCST MON NGT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... WITH DEPARTING VORT MAX TO OUR EAST...H5 HEIGHT RISES AND VERY POOR LAPSE RATES...WITH NEARLY MOIST ADIABATIC PROFILES ABOVE LCL...WILL RESULT IN A DRY DAY ACROSS CWA. THE ONE EXCEPTION WOULD BE IN OUR FAR WESTERN COUNTIES...WHERE A STRAY AFTERNOON SHOWER OR THUNDERSTORM COULD DEVELOP. MAIN STORY TUESDAY WILL BE THE HEAT...WITH MAX TEMPERATURES AOA 90 EAST OF BLUE RIDGE AND IN U80S WEST OF BLUE RIDGE...OR 5-10 DEGREES ABOVE CLIMO IN MANY SPOTS. DEWPOINTS REMAIN IN M60S...WHICH WILL KEEP HEAT INDICES NEAR THE TEMPERATURE. WEAK UPPER LEVEL DISTURBANCE MOVES THROUGH WEDNESDAY INCREASING THE CHANCES FOR SHOWERS/THUNDERSTORMS ACROSS THE REGION. WEAK LAPSE RATES REMAIN...LEADING TO LONG SKINNY CAPE PROFILES...WHICH WILL PREVENT STORMS FROM REALIZING MAX CAPE. ANY SHOWERS/STORMS WOULD WEAKEN QUICKLY NEAR SUNSET...WITH STRONG CONVECTIVE RELIANCE ON INSOLATION. OUR AREA REMAINS IN NORTH TO NORTHWEST FLOW THROUGH THE REMAINDER OF THE PERIOD...WITH CHANCES FOR DIURNAL SHOWERS AND THUNDERSTORMS EACH DAY. LACK OF ADDITIONAL LIFTING MECHANISMS BEYOND DAYTIME HEATING...WILL GENERALLY KEEP ACTIVITY ISOLATED AND THE BEST CHANCES WEST OF BLUE RIDGE. VERY LITTLE RELIEF FROM THE HEAT WITH TEMPERATURES REMAINING 5-10 DEGREES ABOVE NORMAL...THOUGH CONTINUED NORTHWEST FLOW COULD ALLOW FOR A SLIGHT COOLING TREND BY NEXT WEEKEND. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... MRB HAS BEEN IN/OUT OF MVFR VSBY OVNGT...AND THINK THAT WL BE THE SITE TO WATCH. DO NOT XPCT IFR. CHO MAY YET SEE BRIEF RESTRICTIONS AS WELL...BUT WL NEED TO GET RID OF CLDCVR FIRST. VFR CONDS AND LGT SLY FLOW WL PREVAIL THRU THE DAYLIGHT HRS. THERE MAY BE A CPL MTN SHRA/TSRA...BUT NONE SHUD IMPACT TERMINALS. PCPN CHCS SPREAD EAST TNGT BUT STILL REMAIN W OF DC/BALT HUBS. CONFIDENCE IN ANYTHING AFFECTING MRB/CHO TOO LOW TO MENTION IN TAF ATTM. OUTLOOK... MON...LOW PROB SHRA/TSRA LINGER INTO THE DAY...HWVR LOW CONFIDENCE PRECLUDES TAF MENTION. TUE...VFR CONDITIONS UNDER HIGH PRESSURE. WED-THU...LOW AFTERNOON SHOWER/THUNDERSTORM CHANCES RETURN...WITH BRIEF PERIODS OF SUB-VFR NEAR ACTIVITY. && .MARINE... SLY CHANNELING HAS BEEN RELATIVELY ACTV...NECESSITATING SCA TO BE ISSUED FOR THE CORE OF THE MD CHSPK BAY. WRF GDNC SUGGESTS THAT THE WNDS SHUD BE CALMING SLGTLY OVNGT. HV EXPIRATION AT 4AM...AND DO NOT ANTICIPATE EXTENDING IT. SLY FLOW WL CONT THRU MON. THINK THERE WL BE ANOTHER SLY CHANNELING EVENT TNGT...ALTHO LTST PROGS SUGGEST THAT SCA WONT BE REQUIRED. YDA THE SAME CUD BE SAID FOR LAST NGT/THIS MRNG...SO WL NEED TO MONITOR THIS FURTHER. WINDS EXPECTED TO REMAIN SUB-SCA FROM TUESDAY THROUGH REMAINDER OF PERIOD. AFTERNOON THUNDERSTORM CHANCES RETURN TO THE WATERS ON WEDNESDAY AND CONTINUE THROUGH THE REMAINDER OF THE WORKWEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR ANZ531>533-538>541. && $$ SYNOPSIS...MSE/HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...MSE AVIATION...MSE/HTS MARINE...MSE/HTS

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