Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 071443
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1043 AM EDT TUE JUL 7 2015

.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE TODAY INTO THE FIRST PART OF TONIGHT.
A COLD FRONT WILL MOVE IN FROM THE GREAT LAKES ON WEDNESDAY. THE
FRONT WILL SLIDE SLOWLY SOUTH ACROSS THE AREA THURSDAY AND FRIDAY
BEFORE SLOWLY MOVING BACK NORTH OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
REGION REMAINS POSITIONED BETWEEN HIGH PRESSURE OFFSHORE AND AN
APPROACHING COLD FRONT CURRENTLY NOTED OVER IL/IN VIA LATEST IR
SAT. SUBSIDENCE BUILDING IN ALOFT WILL LEAD TO CLEARING SKIES THRU
EARLY AFTN. WAA RIDING ON THE SWLY FLOW WILL PUSH 850MB TEMPS TO
NEAR 19 DEGREES CELSIUS TODAY...RESULTING IN WIDESPREAD 90S...80S
OVER HIGHER ELEVATIONS. AFTN CU WILL FORM WITH AFTN WARMING...BUT
DRIER AIR ALOFT WILL MINIMIZE FURTHER VERTICAL PROGRESSION. THIS
COMBINED WITH NO REAL SFC BOUNDARY SHOULD KEEP MOST OF THE AREA
DRY TODAY.

THE COLD FRONT WILL APPROACH THE WESTERN AREAS LATER TONIGHT AND
MOVE THROUGH THE REGION ON WEDNESDAY. SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS WILL BE POSSIBLE BY THIS EVENING OVER THE
POTOMAC HIGHLANDS WITH COVERAGE INCREASING FROM WEST TO EAST ON
WEDNESDAY. HAVE INCREASED POPS TO CATEGORICAL DURING THE DAY. NOT
EXPECTING SEVERE WEATHER AT THIS TIME AND WILL LEAVE MENTION OUT
OF THE HAZARDOUS WEATHER OUTLOOK.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
MAIN PRECIP ASSOCIATED WITH WEAK COLD FRONT SHOULD BE ENDING BY THU
MORNING...WITH ONLY LINGERING SHOWERY ACTIVITY REMAINING...IF ANY.
LOW CHCS FOR PRECIP DURING THE DAY THU...AS COLD FRONT WILL BE TO
OUR SOUTH AND WE ARE LIKELY UNDER SUBSIDENCE FROM DEPARTING
MID/UPPER LEVEL WAVE. DIFFICULT TO FIND ANY INSTABILITY THU
AFTERNOON...BUT CANNOT RULE OUT A DIURNALLY DRIVEN ISOLATED
SHWR/TSTM ALONG/NEAR ANY NEBULOUS FORCING MECHANISMS. TEMPS NEAR
CLIMO NORMS WITH M/U 80S IN CWA. WEAK COLD FRONT WILL ONLY
TEMPORARILY REDUCE DEWPOINTS...AS BY AFTERNOON THEY WILL RETURN TO
THE U60S...WHICH WILL KEEP HEAT INDICES IN THE M90S.

SECONDARY COLD FRONT...ASSOCIATED WITH LP MOVING ACROSS OHIO
VALLEY...APPEARS TO SLIDE THROUGH THE AREA LATE THU. AT THIS
POINT...POOR TIMING ALONG WITH LIMITED MOISTURE AND INSTABILITY
AHEAD OF THE FRONT...WOULD KEEP PRECIP CHCS FAIRLY LOW. BETTER
MOISTURE/TEMP GRADIENT ALONG FRONT...SO EXPECT TEMPS AND DEWPOINTS
TO DROP FURTHER BEHIND THIS SECONDARY SURGE. FRI HIGHS SHOULD BE IN
L/M 80S...OR A FEW DEGREES BELOW NORMAL.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
QUASI-ZONAL MID/UPPER FLOW PATTERN OF MID-WEEK TRANSITIONS TO NW
FLOW PATTERN THROUGH THE EXTENDED...AS RIDGING BECOMES ESTABLISHED
OVER THE SE STATES. OUR AREA REMAINS ALONG THE PERIPHERY OF THE
RIDGE/ NEAR RING OF FIRE/ WHICH WILL KEEP CHCS FOR UNSETTLED WEATHER
THROUGH THE PERIOD...DESPITE ANY CLEAR FORCING MECHANISMS. WARM
FRONT LOOKS TO LIFT BACK NORTH THROUGH THE REGION OVER THE
WEEKEND...WHICH WILL HELP TO INCREASE TEMPERATURES BY SUN BACK INTO
THE U80S...DESPITE THE NW FLOW. BEST CHCS FOR PRECIP APPEAR MON AS
RIDGING SLIDES FURTHER WEST OVER SOUTHERN PLAINS AND SW TROUGH
DROPS INTO THE AREA.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS FOR THE TAF PERIOD. INCRSG PCPN TONIGHT INTO
WED...WITH ANY SHOWER/TSTM RESULTING IN PSBL SUB-VFR CONDITIONS.
SW WINDS TODAY 8-10 KTS...WITH PSBL OCNL GUSTS TO 20 KTS THIS
AFTN.

VFR CONDS EXPECTED FOR THE REMAINDER OF THE WEEK OUTSIDE OF ANY
SHWR/TSTM ACTIVITY. LOCALIZED SUB-VFR CONDS ARE PSBL DUE TO
SHWRS/TSTMS...THOUGH CHCS FOR TSTMS ARE LOW EACH DAY WITH NEBULOUS
FORCING.

&&

.MARINE...
PERIODIC SCA CONDITIONS ESPECIALLY OVER THE SOUTHERN WATERS AHEAD
OF A COLD FRONT THIS EVENING. WINDS BELOW SCA EXPECTED ON
WEDNESDAY. SHOWERS AND THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND
HEAVY RAINFALL ON WEDNESDAY.

WINDS EXPECTED TO REMAIN BELOW SCA CRITERIA THROUGH THE EXTENDED.
LOW CHCS FOR TSTMS OVER THE WATERS ARE FORECAST EACH DAY THROUGH THE
EXTENDED.

&&

.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...KRW
NEAR TERM...SEARS/KRW
SHORT TERM...MSE
LONG TERM...MSE
AVIATION...SEARS/MSE/KRW
MARINE...MSE/KRW


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