Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 071906
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
306 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/...
SCT-BKN CU FORMING ACROSS THE REGION THIS AFTN WITH DIURNAL
HEATING. 18Z SFC INDICATING SFC TROUGH BEGINNING TO TAKE SHAPE
ALONG THE BLUE RIDGE WHILE THE COLD FRONT WAS EXTENDING ACROSS THE
WESTERN PORTIONS OF THE OH RIVER VALLEY. BAY BREEZE DEVELOPMENT
IMMEDIATELY ON THE CHESAPEAKE BAY COAST HAS BACKED WINDS TO A SE
FLOW...WITH LIGHT SHOWERS PSBL ALONG THIS SFC BOUNDARY THRU THE
LATE AFTN.

12Z MODEL SOLUTION HAS SLOWED PCPN MVG INTO THE CWA A BIT. COULD
SEE SCT SHOWERS...ISO TSTM MVG INTO EASTERN WV THIS EVENING WITH
THE PASSAGE OF THE NEXT SHORTWAVE COMBINING WITH OVER 1000 J/KG
SBCAPE AND THE NOSE OF THE LLJ EDGING INTO WESTERN AREAS. HAVE
CAPPED POPS FOR MOST OF THE NIGHT WEST OF THE BLUE RIDGE AT THIS
TIME...THOUGH CANNOT RULE OUT A STRAY STORM PUSHING EAST.

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 /19Z TUESDAY THROUGH SUNDAY/...
GENERALLY VFR CONDITIONS THRU THE TAF PERIOD. AN ISO SHOWER COULD
IMPACT KMRB THIS EVENING...WITH 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 THRU THE EVENING. AS THE FRONT NEARS
TONIGHT...COULD SEE INCRSG SLY FLOW...RESULTING IN CHANNELING ON
THE CHESAPEAKE BAY. WILL MAINTAIN THE SCA FOR NOW. 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 FROM 10 PM THIS EVENING TO 8 AM EDT
     WEDNESDAY FOR ANZ533-534-537-541>543.

&&

$$
SYNOPSIS...SEARS/RCM
NEAR TERM...SEARS
SHORT TERM...RCM
LONG TERM...IMR
AVIATION...SEARS/IMR/RCM
MARINE...SEARS/IMR/RCM


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