Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 302014
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
414 PM EDT THU JUL 30 2015

.SYNOPSIS...
A COLD FRONT CROSSES THE AREA THIS EVENING AND TONIGHT. HIGH
PRESSURE RETURNS FRIDAY INTO SATURDAY. A WEAK COLD FRONT CROSSES
THE AREA SATURDAY NIGHT...BEFORE HIGH PRESSURE RETURNS TO START
NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
THE MUCH ANTICIPATED COLD FRONT HAS REACHED THE SPINE OF THE
APPALACHIANS AS OF MID AFTERNOON...AND WILL CONTINUE TO MOVE EAST
INTO THE LOCAL AREA THIS EVENING BEFORE PUSHING OFF THE COAST
PRIOR TO DAYBREAK. AS EXPECTED...A BROKEN LINE OF SHWRS AND TSTMS
HAS DEVELOPED AHEAD OF THE FRONT ACROSS THE EASTERN PIEDMONT AND
WILL SLOWLY PROGRESS EASTWARD THRU THE EVENING HOURS. THERE`S
CERTAINLY PLENTY OF INSTABILITY AROUND THIS AFTERNOON WITH DEW PTS
IN THE LOW/MID 70S AND TEMPS IN THE UPR 80S/LOW 90S...CREATING
MIXED LAYER CAPE VALUES OF 1500-2000 J/KG ALONG/WEST OF I-95.
HOWEVER...EFFECTIVE SHEAR VALUES REMAIN QUITE WEAK (<20 KT) WHICH
WILL IN TURN LIMIT THE SVR POTENTIAL OF ANY TSTM THRU THE
EVENING. THAT BEING SAID...CANNOT RULE OUT BRIEF GUSTY WINDS TO
40 MPH AND HEAVY RAIN WITH THE STRONGEST CELLS. WILL CONTINUE WITH
40-60% POPS N-NW THROUGH THE EARLY EVENING HOURS WHERE BEST CHANCE
OF CONVECTION WILL REMAIN...SLIGHT CHC (20%) POPS ACROSS THE SE.
AS THE FRONT MAKES IS WAY INTO AND ACROSS THE REGION LATER THIS
EVENING AND OVERNIGHT...WILL LOWER POPS ACROSS N-NW AREAS WHILE
MAINTAINING 30-40% POPS FROM THE I-95 CORRIDOR ONTO THE EASTERN
SHORE. EXPECTING DRY WX TO RETURN TO N-NW AREAS AFTER MIDNIGHT
WITH 30% POPS E-SE ZONES THROUGH DAYBREAK AS THE FRONT EXITS THE
COAST. GRADUALLY CLEARING SKIES ACROSS THE N-NW OVERNIGHT. LOW
TEMPS FROM THE MID 60S NW TO THE LOW/MID 70S ALONG THE COAST.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
FRIDAY IS LOOKING DRY FOR ALL BUT THE FAR SE PARTS OF THE FA AS
HIGH PRESSURE ARRIVES BEHIND THE DEPARTING FRONT. THE HUMIDITY
WILL BE LOWER AS WELL. HAVE 20% POPS FAR SE...CLOSEST TO THE
STALLING FRONTAL BOUNDARY. HIGHS IN THE UPR 80S TO LOW
90S...EXCEPT MID 80S COAST.

FRIDAY NIGHT AND SATURDAY...
HIGH PRESSURE WILL REMAIN OVER THE AREA FOR DRY WX AND A MOSTLY
CLEAR TO PARTLY CLOUDY SKY. HUMIDITY LEVELS START TO INCREASE
A LITTLE ON SAT. LOWS FRI NIGHT IN THE 60S TO LWR 70S. HIGHS ON
SAT IN THE LOW 90S...EXCEPT MID 80S COAST.

SATURDAY NIGHT AND SUNDAY...
A WEAK COLD FRONT IS NOW SHOWN TO MOVE ACROSS THE AREA SATURDAY
NIGHT. WHAT REMAINS TO BE SEEN IS WHETHER OR NOT IT CAN MUSTER UP
ENOUGH MOISTURE TO PRODUCE A FEW SHOWERS AS IS PASSES. FOR
NOW...HAVE LEFT THE FORECAST DRY AS MODELS NOT ALL THE CONVINCED
THAT IT WILL. MAINLY CLR TO PTLY CLDY WITH LOWS IN THE MID 60S TO
LOW 70S. REMAINING DRY MOST PLACES ON SUNDAY AS HIGH PRESSURE
REBOUNDS. THERE`S A SMALL (20%) CHANCE OF ISOLD SHOWERS ACROSS THE
FAR SE WITH A WEAK COASTAL BOUNDARY STILL IN PLACE. HIGHS SUNDAY
IN THE UPR 80S TO LOW 90S...EXCEPT MID 80S COAST.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
PATTERN BEGINS WITH A MID/UPPER LEVEL RIDGE CENTERED OVER THE SW
CONUS AND AN UPPER LEVEL LOW NEAR HUDSON BAY CANADA. GFS/ECMWF
ARE IN GOOD AGREEMENT WITH THIS OVERALL SETUP INTO TUE...BUT THEN
DIVERGE QUITE A BIT WED/THU...THE OPERATIONAL GFS BEING MUCH
STRONGER/PUSHING FARTHER SOUTH WITH THE UPPER TROUGH THAN THE
ECMWF (OR THE GFS ENSEMBLE MEANS). TYPICAL SUMMERTIME TEMPERATURES
CAN BE EXPECTED MON WITH HIGHS MAINLY RANGING FROM THE MID
80S/AROUND 90 F ALONG THE COAST TO THE LOWER 90S INLAND. GENLY
LOOKS DRY ALTHOUGH WILL MAINTAIN A 20-30% POP IN NE NC DUE TO
POTENTIAL SEABREEZE. FOR TUE-WED...FAIRLY CONFIDENT IN HOT WX FOR
TUE...AS BOTH MODELS HAVE RISING H8 TEMPS AND A W/SW FLOW IN LOW
LEVELS. WILL MAINTAIN A 20% POP DUE MAINLY TO A WEAK CAP WITH H5
HEIGHTS ONLY 585-588 DM. HIGHS MAINLY IN THE MID 90S INLAND AND
90-95 F AT THE COAST. LESS CONFIDENCE FOR WED/THU...GFS WOULD
SUGGEST MUCH COOLER CONDS...WHILE THE ECMWF WOULD SUPPORT HIGHS IN
THE MID 90S TO PERHAPS 100 F. WHILE THE ECMWF/WPC PATTERN WILL
GENLY BE FAVORED (COLD FRONT TO OUR NORTH UNTIL THU AFTN)...THINK
THE DRIER/HOTTER WX WILL ULTIMATELY NOT BE AS HOT AS PREDICTED DUE
TO ANTECEDENT WET/HUMID CONDITIONS OF THE PAST MONTH. FOR NOW WILL
SHOW A SLIGHT COOLING WITH HIGHS WED 90-95 F AND THU UPPER 80S TO
LWR 90S. DEW PTS ARE FORECAST BY MODELS TO MIX OUT INTO THE LOW
60S WEST OF I-95 THROUGH THE PERIOD...GENLY STAYED A LITTLE HIGHER
THAN THIS...MID 60S WEST TO LWR 70S EAST. FOR NOW THIS YIELDS HEAT
INDICES STAYING BELOW 105 F NEXT WEEK. AS FOR POPS...WILL ONLY
HAVE ~20% POPS WED...RISING TO 30% MOST AREAS THU W/ THE APPROACH
OF THE COLD FRONT FROM THE N.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
SHWRS/TSTRMS ALRDY FIRING UP AHEAD OF APPRCHG CDFRNT ACROSS
WRN VA. HIGH RES MODELS IN DECENT AGREEMENT IN BRINGING THIS
CONVECTION E-SE NXT SVRL HRS WITH THE BEST SPRT FOR A LINE OF
CONVECTION FROM RIC-SBY. THUS...ADDED TEMPO GROUP FOR TSRA AT
BOTH THOSE SITES BTWN 20-23Z. MEANWHILE...SHWRS MOVG N FROM THE
OUTER BANKS ARE NOW CROSSING THE ALBEMARLE SOUND AND TRACKING
TOWARD ECG...SO WENT WITH A TEMPO GROUP THERE NEXT FEW HRS.
TIMING CONFIDENCE NOT HIGH ENUF ATTM TO INCLUDE THUNDER IN ORF
BUT DO EXPECT SOME CONVECTION TO APPRCH PHF BY 00Z.

ANY CONVECTION WEAKENS THEN ENDS AFTER SUNSET WITH FROPA AND A
WND SHIFT TO THE NORTH AFTER MIDNIGHT. DCRG CLDNS LATE TONIGHT
WITH ONLY SCT CLDNS XPCTD AFTR 12Z.

OUTLOOK...MAINLY DRY WEATHER IS EXPECTED THROUGH THE WEEKEND WITH
A CHC FOR TSTMS MAINLY SOUTH ON MONDAY.

&&

.MARINE...
LATEST OBS REFLECT SE FLOW ACROSS THE WATERS THIS AFTN...SHIFTING
TO THE S/SW AND TO AVG ~15 KT THIS EVENING. WINDS TURN TO THE NNW
AFTER MIDNIGHT THROUGH FRI MORNING. NOT ANTICIPATING A STRONG
COOL SURGE ON FRI BUT WILL NOT TAKE MUCH TO GET ~15 KT WINDS FRI
MORNING WITH SFC WATER TEMPS AT OR ABOVE 80 F OVER THE BAY/RIVERS
(STAYING JUST BELOW SCA THRESHOLDS FOR NOW BUT WOULD NOT BE
SURPRISED TO SEE A FEW HRS WITH GUSTS TO 20 KT FRI MORNING).
EXPECT WAVES IN THE BAY 2-3 FT THIS EVENING DROP OFF TO 1-2 FT AFTER
MIDNIGHT THEN INCREASE BACK TO 2-3 FT FRI MORNING BEFORE DIMINISHING
FRI AFTN. SEAS AVG 3-4 FT N AND 2-3 FT S. WINDS SHIFT TO THE NNE
MIDDAY FRI...BECOMING E BY LATE IN THE DAY/FRI EVENING. WINDS THEN
TURN BACK TO THE SSW FOR FRI NGT AND SAT...AS THE FRONT WEAKENS
JUST TO OUR SSE ALONG THE CAROLINA COAST. A WEAK FRONT NOW PROGGED
TO CROSS THE AREA SAT NIGHT/EARLY SUN...BEFORE TURNING BACK TO THE
SOUTH LATE SUN INTO NEXT WEEK AS SFC HIGH PRESSURE BECOMES
ANCHORED OVER THE WESTERN ATLANTIC. WAVES SAT INTO NEXT WEEK AVG
1-2 FT IN THE BAY WITH SEAS 2-4 FT.

&&

.TIDES/COASTAL FLOODING...
SLY CHANNELING HAS RESULTED IN SOME NUISANCE-TYPE TIDAL ANOMALIES
ON THE ORDER OF A HALF TO THREE QUARTERS OF A FOOT ABOVE NORMAL AT
BISHOPS HEAD/CAMBRIDGE. WATER LEVELS LOOK TO APPROACH, BUT STILL FALL
SHORT OF MINOR FLOOD THRESHOLDS WITH ASTRONOMICALLY HIGHER TIDE
CYCLE LATE TONIGHT. FALLING WATER LEVELS THEREAFTER AS FLOW TURNS
NORTHERLY INTO FRI MORNING. ANOMALIES MAY RISE AGAIN LATE SAT/SAT
NIGHT IN S FLOW UP THE BAY AHEAD OF ANOTHER WEAK COLD FRONT.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...JDM
NEAR TERM...JDM
SHORT TERM...JDM
LONG TERM...LKB
AVIATION...MPR
MARINE...LKB
TIDES/COASTAL FLOODING...AKQ



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