Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KLWX 210042
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
842 PM EDT SUN JUL 20 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ALONG THE EASTERN SEABOARD THROUGH EARLY
IN THE WEEK. TEMPERATURES WILL SLOWLY RISE THROUGH MIDWEEK AHEAD
OF A COLD FRONT THAT IS EXPECTED TO MOVE INTO THE AREA THURSDAY.
HIGH PRESSURE IS EXPECTED TO RETURN TO THE MID ATLANTIC STATES TO
END THE WORKWEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
HIGH PRESSURE CONTINUES TO WEDGE DOWN THE EAST COAST FROM NEW
ENGLAND THIS EVENING. NE-E WINDS WILL CONTINUE TO USHER IN COOL
CONDITIONS FOR LATE JULY. WEAK FLOW ALOFT AND LITTLE FORCING WILL
RESULT IN DRY CONDITIONS TONIGHT WITH THE EXCEPTION OF A FEW SHOWERS
ALONG THE POTOMAC HIGHLANDS. THESE SHOWERS WILL APPROACH FROM
DISSAPATING CONVECTION ACROSS WV. ONSHORE FLOW WILL KEEP
CONDITIONS CLOUDY OVERNIGHT AND INTO MONDAY MORNING. LOW STRATUS
IS EXPECTED BY DAYBREAK MONDAY SINCE MOISTURE HAS INCREASED IN THE
LOW LEVELS ACROSS THE PAST FEW DAYS. PATCHY FOG IS ALSO POSSIBLE
OVERNIGHT AND INTO MONDAY MORNING FOR VALLEY LOCATIONS WEST OF THE
BLUE RIDGE AND ACROSS THE NRN AND CENTRAL PIEDMONT. FCST MIN TEMPS
ARE THE MID TO UPPER 60S AND AROUND 70S NEAR THE WATERS.

PREVIOUS DISCUSSION...
ONSHORE FLOW PERSISTS ON MONDAY...WITH MODELS SHOWING
DEWPOINTS/PRECIPITABLE WATERS INCREASING A BIT. IN TANDEM WITH AN
INCREASE IN MOISTURE WOULD BE SLIGHTLY BETTER INSTABILITY. EXPECT
SCATTERED SHOWERS...ESPECIALLY WEST OF THE INTERSTATE 95 CORRIDOR
PER SREFS. ISOLATED THUNDERSTORMS WILL ALSO BE POSSIBLE BUT NO
SEVERE WEATHER IS EXPECTED.

FOLLOWED A BLEND OF BIAS CORRECTED SREFS AND ADJMAV GUIDANCE THROUGH
MONDAY.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
FLAT RIDGE BUILDS IN MONDAY NIGHT INTO TUESDAY...PROMOTING WARMER
TEMPERATURES. EXPECT MORE IN THE WAY OF SUNSHINE AS WELL BY TUESDAY.
A FEW DIURNAL THUNDERSTORMS WILL BE POSSIBLE ESPECIALLY NEAR THE
RIDGES BUT FLAT RIDGE MAY LIMIT CONVECTIVE COVERAGE FOR TUESDAY.

RIDGE STARTS TO GET SUPPRESSED TO THE SOUTH IN ADVANCE OF THE NEXT
TROUGH ON WEDNESDAY...BUT IT WILL STILL BE A WARM DAY AND DAYTIME
HEATING AND PRE-FRONTAL TROUGH MAY TRIGGER SCATTERED AFTERNOON
THUNDERSTORMS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
UPPER LEVEL ENERGY WILL MOVE ACROSS THE EASTERN GREAT LAKES AND
EASTERN OHIO VALLEY WEDNESDAY BEFORE SLIDING SOUTHEASTWARD INTO THE
MID ATLANTIC WEDNESDAY NIGHT INTO THURSDAY.

AN ASSOCIATED SURFACE COLD FRONT WILL MOVE PARALLEL TO THE OHIO
VALLEY WEDNESDAY...BRINGING A CHANCE OF SHOWERS OR A
THUNDERSTORM...MAINLY IN THE NORTHERN POTOMAC HIGHLANDS. THE CHANCE
FOR SHOWERS AND THUNDERSTORMS LINGER WEDNESDAY NIGHT AS THE SURFACE
FRONT MOVES INTO THE MID ATLANTIC REGION.

MORE FREQUENT SHOWERS AND A COUPLE OF STRONGER THUNDERSTORMS MAY
DEVELOP DURING THE DAY THURSDAY DUE TO A COMBINATION OF THE
INGREDIENTS OF UPPER LEVEL ENERGY...A SURFACE COLD
FRONT...ADDITIONAL MOISTURE AND DAYTIME HEATING. THE STRONGER
THUNDERSTORMS COULD PRODUCE DAMAGING WINDS AND LOCALLY HEAVY RAIN.
HIGH CAPE AND LOW TO MODERATE SHEAR COULD LEAD TO THE DAMAGING
WINDS...WHILE PRECIPITABLE WATER VALUES OF AROUND 2 INCHES COULD
INDICATE HEAVY RAIN WOULD BE A THREAT FROM THE STORMS. AS OF
NOW...TIMING OF THE HEAVIEST ACTIVITY APPEARS TO BE LATE THURSDAY
MORNING TO EARLY THURSDAY EVENING.

A SURFACE COLD FRONT WILL FINALLY PUSH THROUGH OUR REGION THURSDAY
NIGHT TO ALLOW FOR A RIDGE OF HIGH PRESSURE TO BUILD IN FROM THE
NORTHWEST. THIS FRONT HAS THE POTENTIAL TO STALL NEAR THE VIRGINIA
AND NORTH CAROLINA BORDER THURSDAY NIGHT INTO FRIDAY...THUS MAYBE
KEEPING A SLIGHT CHANCE OF RAIN SHOWERS ACROSS THE SOUTHERN
TWO-THIRDS OF THE CWA WITH A SLIGHT CHANCE OF THUNDERSTORMS ACROSS
THE VIRGINIA PIEDMONT AND MAIN STEM CHESAPEAKE BAY.

HIGH PRESSURE SHOULD GRADUALLY PUSH THE FRONT FARTHER SOUTH TO ALLOW
COOLER AND DRIER AIR TO MOVE IN ACROSS THE CWA FRIDAY AFTERNOON
THROUGH MIDDAY SATURDAY. THE HIGH IS EXPECTED TO MOVE OFFSHORE
SATURDAY AFTERNOON AND SATURDAY NIGHT. AN ONSHORE FLOW DEVELOP
DURING THE PERIOD...AIDING IN AN INCREASE IN LOW LEVEL MOISTURE.
GIVEN THE UNCERTAINTY OF THE POSITION OF THE HIGH...NEAR LONG ISLAND
OR THE TIDEWATER OF VIRGINIA...WE LEFT A CHANCE OF RAIN SHOWERS
SATURDAY AND A SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM SATURDAY
NIGHT. DESPITE THE HIGH BEING THE FAVORITE...BOTH THE EURO AND GFS
INDICATE A FEW RIPPLES IN THE UPPER LEVEL FLOW THAT MAY INDICATE A
WEAK DISTURBANCE OR TWO MAY FIND ITS WAY ACROSS OUR CWA...HENCE
THE CHANCE OF A SHOWER OR STORM.

SUNDAY APPEARS TO BE A PRECURSOR OF WHAT IS TO COME OUR WAY DURING
THE MIDDLE PART OF NEXT WEEK. SOME UPPER LEVEL ENERGY WILL TRY TO
SQUEEZE AROUND THE PERIPHERY OF THE WEAK UPPER LEVEL HIGH AND PUSH
INTO OUR NORTHWESTERN ZONES SUNDAY. THERE IS A CHANCE OF SHOWERS AND
A THUNDERSTORM SUNDAY WITH THE BEST LIKELIHOOD IN THE POTOMAC HIGHLANDS.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR CONDITIONS THIS EVENING. IFR CIGS ARE EXPECTED AT MRB/CHO/IAD
LATE TONIGHT INTO MONDAY MORNING AS EASTERLY FLOW CONTINUES TO
USHER IN MOISTURE. MVFR VSBYS ARE POSSIBLE BUT MAIN RESTRICTION
WILL BE CIGS OVERNIGHT. ITS POSSIBLE THAT CHO AND MRB COULD SEE
IFR VSBY BUT CLOUD COVER WILL LIKELY LIMIT IT.

SLIGHT CHANCE OF MAINLY AFTERNOON TSRA MON/TUE...THEN CHANCE OF TSRA
INCREASES FOR WED. ANY SHOWERS OR ISOLATED THUNDERSTORMS THAT DEVELOP
WEDNESDAY AND WEDNESDAY NIGHT COULD BRING MVFR CONDITIONS TO ANY
OF THE TERMINALS.

THERE IS A BETTER CHANCE OF IFR OR LIFR CONDITIONS AT ANY OF THE
TERMINALS THURSDAY AS LOCALLY HEAVY RAINFALL AND GUSTY WINDS COULD
ACCOMPANY THE SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
HIGH PRESSURE ALONG THE EASTERN SEABOARD WILL KEEP AN EASTERLY FLOW
THROUGH EARLY WEEK...MAINLY 10 KT OR LESS THROUGH MONDAY. AS WINDS
TURN SOUTHEAST...WINDS MAY INCREASE CLOSER TO 15 KT FOR TUESDAY.

SMALL CRAFT ADVISORIES MAY BE NEEDED BY WEDNESDAY NIGHT
AS SOUTH TO SOUTHWESTERLY WINDS INCREASE AHEAD OF AN APPROACHING
SURFACE COLD FRONT.

&&

.TIDES/COASTAL FLOODING...
TIDAL ANOMOLIES HAVE RISEN TO A HALF FOOT THIS EVENING ON THE MD
CHESAPEAKE BAY AND POTOMAC RIVER. LIGHT FLOW SHOULD KEEP WATER
LEVELS BLW MINOR FLOODING TONIGHT AND MONDAY.


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...BPP/KLW
NEAR TERM...BPP/HAS
SHORT TERM...BPP
LONG TERM...KLW
AVIATION...BPP/HAS/KLW
MARINE...BPP/KLW
TIDES/COASTAL FLOODING...HAS







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.