Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 080115 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 915 PM EDT TUE JUL 7 2015 .SYNOPSIS... A COLD FRONT WILL SLIDE SOUTHEAST INTO THE AREA TONIGHT AND WEDNESDAY. THE FRONT WILL STALL IN THE AREA WEDNESDAY NIGHT AND A LOW PRESSURE WILL RIDE EASTWARD ALONG THE FRONT ON THURSDAY. THE FRONT WILL SLIDE SOUTH OF THE AREA FRIDAY AND WEAKEN. HIGH PRESSURE WILL DOMINATE OVER THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... S/WV ENERGY HAS SUPPORTED TSRA CROSSING WVA AND INTO THE CWFA. AMS AHD OF LINE HAS SUFFICIENT INSTBY...ALTHO THAT LVL DIMINISHES FURTHER EAST. /2000+ J/KG CAPE FROM RNK SNDG BUT LESS THAN 1000 J/KG AT IAD./ SHEAR PROFILES NOT THAT GREAT...PLUS DIURNAL HEATING HAS BEEN LOST WITH THE SETTING SUN. OVERALL...XPCT TSRA TO BE NON- SVR...AND WKNG THRU THE EVNG. SOME GUSTY WINDS /30-40 KT/ PSBL NEXT HR OR TWO. HV BUMPED POPS UPWD W OF THE BLURDG ONCE ALREADY...AND BASED ON LTST TRENDS SUSPECT I/LL BE DOING IT YET AGAIN. RAP RUNS SUGGEST IT MAY MAKE IT TO DC...ALTHO LTST RAP LESS EMPHATIC THAN PRVS CYCLES. COLD FRONT APPROACHES THE REGION WED MORNING...WITH INCRSG COVERAGE OF PCPN OUT AHEAD OF THE SYSTEM. AS IT SEEMS TO BE WITH COLD FRONTS THIS SUMMER...THE FLOW ALOFT BECOMES NEARLY ZONAL...RESULTING IN THE FRONT TAKING A MORE EAST- WEST POSITION THAN NE-SW. WITH THIS SET UP AS WELL...THE FRONT WILL HAVE MINIMAL PROGRESSION TO THE SOUTH...WITH IT STALLING NEAR THE MASON-DIXON WED-WED NIGHT. INSTABILITY LOOKS TO BE MARGINAL FOR MOST OF THE DAY...BUT ENOUGH TO WARRANT TSTMS IN THE FORECAST. OVERALL DYNAMICS WOULD KEEP ANY SVR THREAT MINIMAL. DESPITE THE CLOUD COVER...HIGH TEMPS ON WED EXPECTED INTO THE UPPER 80S TO LOWER 90S. HEAT INDICES WILL REMAIN BELOW THE CENTURY MARK. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... WAVE OF LOW PRESSURE WILL RIDE ALONG THE FRONT TO OUR NORTH ON THURSDAY. THIS WILL ALLOW WARM AIR TO REMAIN AND HIGHS MAY ONCE AGAIN REACH THE 90S ACROSS MUCH OF THE AREA. MOST OF THE UPPER LEVEL ENERGY WITH THIS WAVE APPEARS TO STAY NORTH OF US...BUT SUGGEST A DECENT AMOUNT OF SHEAR AND CAPE...SO A STRAY SEVERE THUNDERSTORM DOESNT LOOK IMPOSSIBLE. AS THE LOW PASSES TO THE NORTH THE COLD FRONT WILL SLIDE SOUTHEAST ACROSS OUR AREA THURSDAY NIGHT...PUTTING AN END TO THE 90S FOR A DAY OR TWO. HUMIDITY WILL ALSO LOWER AND THE CHANCE OF SHOWERS AND THUNDERSTORMS APPEARS PRETTY LOW ON FRIDAY...BUT DID NOT COMPLETELY REMOVE THEM FROM THE FORECAST JUST YET IN CASE FUTURE MODELING IS SLOWER IN DRAGGING THE FRONT THROUGH. && .LONG TERM /SATURDAY THROUGH TUESDAY/... COLD FRONT WEAKENS AND MOVES AWAY FROM THE REGION FRI NIGHT AS A HIGH PRES BUILDS IN FOR SAT. UPPER FLOW TRANSITIONS TO NW INTO SUN AS A FRONTAL BNDRY LIFTS LATER THAT DAY. UPPER LEVEL DISTURBANCES AFFECTS THE AREA MON INTO TUE. BEST CHANCE FOR PRECIP APPEARS TO BE SUN THROUGH TUE. TEMPS WILL BE CLOSE TO NORMAL. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... GENERALLY VFR CONDITIONS THRU THE NGT. LINE OF TSRA CROSSING THE APLCNS ATTM. XPCT A BIT OF A WEAKENING TREND...BUT A FEW STORMS LKLY WL MAKE IT TO THE BLURDG. LOW CONFIDENCE WHAT WL HPPN THEREAFTER. MRB NEAREST STORMS...AND ADDED MVFR TEMPO GROUP TO TAF. HWVR...A BREAK HAS DVLPD IN THE LINE...AND ITS PSBL THAT EVEN MRB MAY MISS THIS ACTIVITY. AM WITHHOLDING ANY MENTION DC/BALT METROS ATTM SINCE CONFIDENCE TOO LOW. WORST CASE SCENARIO WOULD BE FOR BRIEF AOB IFR W/ GUSTY WINDS 30-40 KT. BASED ON CURRENT SPEED...EXTRAPOLATION BRINGS PCPN TO MRB BTWN 02-03Z...CHO/IAD BTWN 03-04Z...AND ELSW AFTR 04Z /ASSUMING IT SURVIVES/. THE BETTER CHC FOR PCPN IMPACTING THE TERMINALS TOMORROW. COULD SEE PCPN AS EARLY AS 12Z...BUT INCRSG CHC AFTR 15/16Z...LASTING THRU THE AFTN...TAPERING OFF WED EVENING. SUB-VFR CONDITIONS PSBL IN ANY STORM. WINDS S-SW THIS AFTN 8-12 KTS...BCMG S 5 KTS OR LESS TONIGHT. WINDS WILL INCREASE AGAIN FROM THE SW AFTR 12Z WED...BCMG LIGHT/VRB WED NIGHT AS THE FRONT STALLS OVER THE REGION. DEPENDING ON WHERE THE BOUNDARY ALIGNS...COULD SEE SUB-VFR CONDITIONS WITH DEVELOPING STRATUS/FOG. MAIN CONCERN THURSDAY IS POTENTIAL FOR A GUSTY THUNDERSTORM DURING THE AFTERNOON AND EVENING. CONDITIONS SHOULD OTHERWISE BE VFR WITH SOUTHWESTERLY WINDS BECOMING NORTHWESTERLY ON FRIDAY. VFR CONDITIONS EXPECTED FOR FRI NIGHT THROUGH THE WEEKEND. && .MARINE... SUB-SCA CONDITIONS ON THE WATERS ATTM. AS THE FRONT NEARS TONIGHT...COULD SEE INCRSG SLY FLOW...RESULTING IN CHANNELING ON THE CHESAPEAKE BAY. WILL MAINTAIN THE SCA FOR NOW...BUT WL BE REEVALUATING IT SHORTLY. AS THE WINDS VEER TO THE SW WED...SUB- SCA CONDITIONS. LOW PRESSURE PASSING TO THE NORTH MAY BRING SOME SCA-LEVEL WINDS TO THE WATERS ON THURSDAY. WINDS APPEAR TO DIMINISH BY FRIDAY AFTERNOON AFTER THE SYSTEM HAS PASSED OUR AREA. THUNDERSTORMS WILL ALSO REMAIN A CONCERN THURSDAY. SUB-SCA CONDITIONS EXPECTED FOR FRI NIGHT AND SAT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT WEDNESDAY FOR ANZ533-534- 537-541>543. && $$ SYNOPSIS...SEARS/RCM NEAR TERM...HTS/SEARS SHORT TERM...RCM LONG TERM...IMR AVIATION...HTS/SEARS/RCM/IMR MARINE...HTS/SEARS/RCM/IMR

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