Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 010800
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
400 AM EDT WED JUL 1 2015

.SYNOPSIS...
A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST TODAY.
THE FRONT WILL STALL OUT IN CENTRAL VIRGINIA TONIGHT. THE FRONT
WILL LINGER OVER THE REGION THROUGH THE WEEKEND...WITH SEVERAL
WAVES OF LOW PRESSURE MOVING EAST ALONG IT.

&&

.NEAR TERM /THROUGH TONIGHT/...
STRONG STORMS ASSOCIATED WITH POTENT SHORTWAVE TROUGH ARE MOVING
OFF TO THE EAST. WILL KEEP AN EYE OUT FOR A LINGERING SHOWER
ACROSS NORTHERN AREAS THROUGH THIS MORNING...BUT OTHERWISE SHOULD
BE MAINLY DRY. LOW PRESSURE IS LIFTING OUT OF THE GREAT
LAKES...WITH REAL PUSH OF DRIER AIR WELL TO OUR NW. LOOSELY
DEFINED FRONTAL ZONE SAGS SOUTH TODAY. NOT A LOT OF FORCING IN
PLACE...AND INSTBY LOOKS TO BE RATHER MEAGER. HAVE TRIMMED BACK
POPS OVER PREVIOUS FORECAST. MODELS WHICH DO GENERATE PRECIP FOCUS
MAINLY SOUTH OF DC...AND HAVE THUS LEFT A 30 POP THERE. HIGHS
TODAY STILL ABLE TO WARM INTO THE 80S IN MOST LOCALES.

FRONT MAY MAKE IT TOWARD SOUTHERN VA TONIGHT. ANY SHOWERS WILL
TAPER OFF DURING THE EVENING WITH A DRY OVERNIGHT. A BIT OF LOWER
DEWPOINT PUSH IN N/W CWA...BUT OVERALL STILL EXPECTING LOWS IN THE
60S TO AROUND 70 IN URBAN CENTERS.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
LOW PRESSURE WILL BE TRACKING ALONG THE FRONTAL ZONE...REACHING
THE LOWER OHIO VALLEY ON THURSDAY. THIS WILL DRAW SOME MOISTURE
INTO THE FRONT OVER OUR REGION. STILL SOME TIMING/PLACEMENT
DIFFERENCES AMONGST MODELS...BUT EXPECT A S TO N PROGRESSION OF
SHOWERS AND EMBEDDED THUNDER (AT LEAST SOME INSTBY MAY BE
PRESENT...ESPECIALLY SOUTHERN TIER). QUESTIONABLE HOW MUCH IF ANY
PRECIP REACHES THE M-D LINE DURING THE DAY ON THURSDAY. HEAVIEST
ACTIVITY LIKELY STAYS OVER OHIO VALLEY DURING THE DAY.
TEMPERATURES WILL BE LIMITED DOWN A FEW DEGREES BY THE CLOUDS AND
PRECIP...UPPER 70S TO MID 80S.

THURDAY NIGHT THROUGH FRIDAY NIGHT...A GREAT DEAL OF UNCERTAINTY
REMAINS...WITH DIFFERING SOLUTIONS ABOUT THE PATH AND TIMING OF
LOW PRESSURE SYSTEMS RIDING EAST ALONG THE FRONT. SOME GUIDANCE
LIKE THE GFS BRINGS A SIGNIFICANT WAVE OF LOW PRESSURE SLOWLY
ACROSS THE REGION DURING THIS PERIOD...WHICH WOULD RESULT IN
SHOWERS AND PERHAPS A FEW ISOLATED THUNDERSTORMS. THE EUROPEAN IN
CONTRAST IS NOTABLY SLOWER...WITH THE MAIN WAVE OF LOW PRESSURE
WAITING UNTIL FRIDAY NIGHT TO BEGIN AFFECTING THE AREA. THE
CANADIAN GGEM IS EVEN SLOWER...HOLDING THE MOST SIGNIFICANT LOW
BACK EVEN LONGER. WITH CONSIDERABLE UNCERTAINTY IN THE
FORECAST...NO SIGNIFICANT CHANGES WERE MADE...SO KEPT CHANCE TO
LOW- END LIKELY POPS AND TEMPS SOMEWHAT COOLER THAN NORMAL
IN THE FORECAST.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
UNCERTAINTY REMAINS ABOUT THE WEEKEND INTO EARLY NEXT WEEK WITH
THE AFOREMENTIONED SIGNIFICANT TIMING DISCREPENCIES REGARDING
PASSING DISTURBANCES BETWEEN VARIOUS MODELS. THIS MAKES ANY
ATTEMPT TO IRON OUT DETAILS VERY DIFFICULT. THE ONE CONSTANT IS
THE APPARENTLY NEVER LEAVING QUASI-STATIONARY FRONT. INHERITED
GENERALLY CHANCE POPS THRU THE PERIOD AND DID NOT MAKE MAJOR
CHANGES. TEMPS START OUT BELOW NORMAL AND *MAY* RISE TO NEAR
NORMAL IF THE FRONT CAN FINALLY NUDGE ITS WAY NORTH OF US EARLY
NEXT WEEK. CONFIDENCE IS LOW.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
PRECIP HAS EXITED THE AREA AND AM NOT EXPECTING FURTHER IMPACTS
THROUGH THE MORNING. WILL HAVE TO WATCH POTENTIAL FOR LOW CIGS
DEVELOPING THROUGH DAYBREAK...PERHAPS SOME FOG TOO...BUT THINK MID
LEVEL CLOUDS WILL HELP LIMIT THIS. TODAY SHOULD BE LARGELY
VFR...BUT FRONT SINKING INTO AREA MAY DEVELOP ISOLATED
THUNDERSTORMS THIS AFTERNOON. IMPACTS SEEM UNLIKELY. NEXT CHANCE
OF PRECIP WILL ARRIVE THURSDAY...WITH GREATEST POTENTIAL FOR
IMPACTS AT CHO.

FROM THURSDAY NIGHT ONWARD...MAIN CONCERN IS POSSIBLE IFR CIGS AND
VIS FROM OCCASIONAL HEAVIER SHOWERS OR THUNDERSTORMS AS A FRONT
REMAINS STALLED IN THE GENERAL AREA. WITH THE FRONT NEARBY...WINDS
WILL BE HARD TO PREDICT WITH SIGNIFICANT CERTAINTY UNTIL THE
PERIOD DRAWS CLOSER.

&&

.MARINE...
WINDS HAVE TAKEN DOWNTURN AFTER EXITING STORMS AND SCA SHOULD
EXPIRE ON TIME. GRADIENT WEAK ENOUGH THAT WINDS WILL BE IN THE 10
KT RANGE FROM THE SW TODAY. AN ISOLATED STORM IS POSSIBLE BY MID-
LATE AFTERNOON...BUT THIS IS IN QUESTION. EXPECT SUB-SCA WINDS
THROUGH THURSDAY...EVENTUALLY TAKING ON NORTHERLY COMPONENT.

MAIN CONCERN IN THE EXTENDED FOR MARINE IS OCCASIONAL HEAVIER
SHOWERS AND THUNDERSTORMS...WITH APPEARS POSSIBLE JUST ABOUT EVERY
DAY FROM FRIDAY INTO EARLY NEXT WEEK. WINDS SHOULD GENERALLY BE
SUB SCA BUT AS DISTURBANCES PASS THRU THE AREA...A PERIOD OF SCA
WINDS IS NOT IMPOSSIBLE.

&&

.TIDES/COASTAL FLOODING...
WATER LVLS RUNNING ABOVE NORMAL EARLY THIS MORNING...MODULATED BY
RECENT STORMS. HOWEVER...STILL SHOULD BE ENOUGH ABOVE NORMAL FOR
POTENTIAL MINOR COASTAL FLOODING AT ANNAPOLIS AND DC/ALEXANDRIA
FOR MORNING TIDE CYCLE. LOW CONFIDENCE ON ANY FUTURE TIDE
ISSUES...BUT ANOMALIES SHOULD DECREASE SOME AS FRONT PUSHES
THROUGH.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR
     DCZ001.
MD...COASTAL FLOOD ADVISORY UNTIL 7 AM EDT THIS MORNING FOR MDZ014.
     COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR
     MDZ013.
VA...COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR
     VAZ053-054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT EARLY THIS MORNING FOR
     ANZ531>533-537-539>542.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     ANZ534-543.
     COASTAL FLOOD ADVISORY FROM 7 AM TO 10 AM EDT THIS MORNING FOR
     ANZ535.

&&

$$
SYNOPSIS...RCM
NEAR TERM...ADS
SHORT TERM...ADS/RCM
LONG TERM...RCM
AVIATION...ADS/RCM
MARINE...ADS/RCM
TIDES/COASTAL FLOODING...



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