Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 011754
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
154 PM EDT SAT AUG 1 2015

.SYNOPSIS...
HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST TODAY. A WEAK
FRONTAL BOUNDARY SLIDES OFFSHORE LATE SATURDAY INTO SATURDAY
NIGHT...BEFORE HIGH PRESSURE RETURNS TO START NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
LATEST WX ANALYSIS FEATURES WEAK SFC COLD FRONT IN PLACE FROM NEAR
THE COASTAL CAROLINAS INTO THE DEEP SOUTH...WITH ~1018MB SFC HIGH
PRESSURE CENTERED FROM THE CENTRAL/SOUTHERN APPALACHIANS BACK INTO
THE MID MS RIVER VLY. ALOFT, EARLY MORNING WATER VAPOR IMAGERY AND
SUBJECTIVE ANALYSIS DEPICT AN UPPER LEVEL TROUGH CENTERED OVER
HUDSON BAY AND EXTENDING SOUTH INTO THE GREAT LAKES REGION INTO
THE OH VALLEY/NORTHERN MID-ATLANTIC.

DESPITE THE UPR-LEVEL TROUGHING IN PLACE OVER THE EASTERN CONUS,
00Z/01 RAOB ANALYSIS INDICATES PW VALUES ~1 S.D. BELOW NORMAL
(0.82" WAL, 0.92 IAD, 0.67" RNK, 0.76" GSO) ACROSS THE REGION.
THIS LACK OF LLVL MOISTURE W/SFC HI PRES TO THE WEST SHOULD ALLOW
FOR ANOTHER DRY DAY...ALBEIT VERY WARM. LOCAL THICKNESS TOOLS ARE
IN GENERAL AGREEMENT WITH MOS GUIDANCE WRT HIGHS, DEPICTING MAXIMA
IN THE LOW TO MID 90S UNDER A SUNNY TO MOSTLY SUNNY SKY.

WEAK SFC BOUNDARY/TROUGH TO THE SOUTH SLIDES OFFSHORE OF THE
SOUTHEAST COAST TONIGHT, AS THE SFC HI PRES CENTER BUILDS IN
FROM THE W. LOWS SAT NIGHT AGAIN IN THE MID 60S TO LWR 70S.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
UPPER TROUGH REMAINS IN PLACE OVER HUDSON BAY. THIS WILL ALLOW
FOR DRY CONDITIONS TO PERSIST FOR SUNDAY AND MONDAY FOR MOST OF
THE AREA W/SIMILAR TEMPS WITH THE SFC HI IN PLACE OVER THE AREA.
DID INCLUDE A 20% CHANCE OF A TSTM ON SUNDAY, BUT ONLY OVER NE NC
WITH SOME SEABREEZE EFFECTS ACTING AS A FOCUS FOR ISO TSRA.
ANOTHER SMALL CHC FOR TSRA MONDAY, AS SHORTWAVES ON THE PERIPHERY
OF THE UPPER LOW DROP FROM THE OH VLY INTO THE REGION. PW VALUES
REMAIN ON THE LOW SIDE, AT OR JUST BELOW SEASONAL NORMAL. THUS,
WILL KEEP POP IN SLIGHT CHC RANGE AT MOST FOR NOW.

TEMPERATURES ALSO RAMP UP ON MONDAY ON S/SW RETURN FLOW SETUP.
EXPECT HIGHS IN THE MID 90S WITH HEAT INDICES PEAKING AOA 100
DEGREES.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
PATTERN BEGINS WITH WITH A MID/UPPER LEVEL RIDGE CENTERED OVER THE
SW/SRN CONUS AND AN UPPER LEVEL LOW NEAR GEORGIAN/HUDSON BAY CANADA.
LATEST GFS/ECMWF ARE INTO IMPROVED AGREEMENT COMPARED TO
EARLIER RUNS WITH THIS OVERALL SETUP THROUGH THE MIDDLE OF NEXT
WEEK. THIS TRANSLATES INTO HOT WX TUE/WED WITH H8 TEMPS RISING
TO 19-21 C ACRS THE AREA. WILL FORECAST HIGHS IN THE MID 90S OVER
MUCH OF THE AREA...A LITTLE COOLER (HIGHS UPPER 80S TO LOWER 90S)
CLOSER TO THE COAST DUE TO SOME POTENTIAL FOR AFTN WINDS SHIFTING
MORE TO THE SE/ONSHORE. ALSO A LITTLE COOLER OVER THE FAR NORTH AS
SFC FRONT WILL NOT BE THAT FAR NORTH OF THE REGION AND COULD LEAD TO
MORE AFTN CLOUDS AND SOMEWHAT HIGHER CHANCES FOR PRECIP. DEW PTS ARE
FORECAST BY MODELS TO MIX OUT INTO THE UPPER 50S/LOW 60S WEST OF I-
95 TUE/WED...GENLY STAYED A LITTLE HIGHER THAN THIS...LWR TO MID 60S
WEST TO LWR 70S EAST. FOR NOW THIS YIELDS HEAT INDICES PEAKING
AROUND 100 F OR A TAD HIGHER BUT REMAINING BELOW 105 F ADVSY
THRESHOLDS. AS FOR POPS TUE/WED...MODELS SHOW VERY LITTLE IN THE WAY
OF DEEP FORCING/MOISTURE BUT GIVEN FAIRLY LOW H5 HGTS AND HOT LOW
LEVELS WILL MAINTAIN AT LEAST A 20% POP BOTH DAYS IN THE
AFTN/EVENING TIMEFRAME (UP TO 30% WED ACRS THE NORTH).

BY THU/FRI...UPPER RIDGING AMPLIFIES ACRS THE WRN CONUS GRADUALLY
CARVING OUT A DEEPER TROUGH OVER THE ERN CONUS. THIS SHOULD BE
ENOUGH TO EVENTUALLY DRIVE THE COLD FRONT SOUTH INTO THE MID
ATLC/CAROLINAS THU INTO FRI (THOUGH HARD TO SAY IF THE FRONT CLEARS
THE AREA ON FRI). RAISED POPS TO 40% N AND 30% S THU AFTN/THU
NIGHT...WITH A 20-30% POP FOR FRI. HIGHS TREND DOWN INTO THE
MID/UPPER 80S N TO THE LWR 90S S ON THU...AND INTO THE 80S ALL AREAS
ON FRI.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
A WEAK TROUGH/FRONTAL BOUNDARY WILL LINGER ALONG THE COAST TODAY...
ESPECIALLY ACROSS NE NC. VFR CONDS EXPECTED THRU THE TAF PERIOD WITH
MOSTLY LIGHT SE-SW WIND. KECG AND KSBY MAY EXPERIENCE BKN CIGS IN
THE AFTN/EVENING AS THE BNDRY GETS PUSHED OFFSHORE. SKIES
GRADUALLY CLEAR OVERNIGHT AS HIGH PRESSURE BUILDS INTO THE MID
ATLANTIC REGION THROUGH SUNDAY. ANOTHER TROUGH CROSSES THE AREA ON
MONDAY...FOLLOWED BY MORE HIGH PRESSURE.

&&

.MARINE...
S-SW WINDS THIS MORNING TURN BACK TO THE SSE BY THIS AFTN WITH
SPEEDS AOB 15 KT. GENERALLY LIGHT WINDS AND GOOD BOATING CONDITIONS
PREVAIL THROUGHOUT THE WEEKEND WITH SEABREEZES DEVELOPING EACH
AFTN. EXPECT LIGHT WEST WINDS IN THE MORNING...TURNING TO THE E/SE
AT AROUND 10 KT IN THE LATE AFTN/EVENING. WAVES AVERAGE 1-2 FT IN
THE BAY WITH SEAS 2-3 FT. PRESSURE GRADIENT INCREASES MON/MON NIGHT
WITH SLY WINDS INCREASING INTO THE 15-20 KT RANGE (POSSIBLY TO
MARGINAL SCA CONDS) WITH WAVES 2-3 FT AND SEAS 3-5 FT. HIGH
PRESSURE RETURNS TO THE REGION TUESDAY THROUGH WEDNESDAY WITH
S-SW WINDS AOB 15 KT AND WAVES 1-2 FT/SEAS 2-4 FT.

&&

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

&&

$$
SYNOPSIS...MAM
NEAR TERM...MAM
SHORT TERM...MAS/MAM
LONG TERM...LKB
AVIATION...BMD/JEF
MARINE...BMD



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