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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 181511
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1111 AM EDT TUE JUN 18 2013

.SYNOPSIS...
WEAK LOW PRESSURE TRACKS ACROSS THE REGION TODAY THROUGH TONIGHT
AS A COLD FRONT PUSHES SOUTH. THE LOW MOVES OFF THE COAST
WEDNESDAY WHILE THE COLD FRONT SETTLES ACROSS THE CAROLINAS. HIGH
PRESSURE BUILDS INTO THE REGION FROM THE NORTH THURSDAY THROUGH
FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
LATEST WATER VAPOR IMAGERY CONTINUES TO DEPICT BROAD CYCLONIC
FLOW OVER MUCH OF THE CNTRL AND ERN CONUS AS STRONG UPPER LOW
PRESSURE LOCATES OVER CNTRL QUEBEC. TWO PROMINENT SHORTWAVES IN
THE CYCLONIC FLOW REGIME WILL IMPACT THE REGION THROUGH TONIGHT.
THE FIRST IS LOCATED OVER KY/TN WITH THE SECOND SHORTWAVE
CURRENTLY DIGGING OVER THE UPPER MIDWEST. AT THE SFC...COLD FRONT
HAS ALIGNED FROM THE OH VALLEY INTO SRN PA AS A BROAD AREA OF LOW
PRESSURE EXISTS ACROSS THE MID ATLANTIC REGION. LATEST REGIONAL
RADAR TRENDS SHOW BROAD AREA OF SHOWERS ACROSS WRN VA...WITH MORE
ISOLATED SHOWERS ACROSS THE LOCAL AREA.

FOR TODAY...SFC LOW WILL STRENGTHEN AS IT PROGRESSES EWD ACROSS
NRN NC/SRN VA AS THE COLD FRONT SLOWLY DROPS SWWD. SHOWERS WILL
INCREASE IN COVERAGE AN INTENSITY AS THEY APPROACH THE LOCAL AREA
FROM THE WEST. MID LEVEL SHORTWAVE AND DIVERGENCE ALOFT WILL
PROVIDE ABUNDANT FORCING FOR ASCENT ACROSS THE REGION. INCREASING
LOW LEVEL FLOW WILL ADVECT DEEP GULF MOISTURE INTO THE REGION
(850-700MB MOISTURE FLUX +2-3 STD DEV) WITH PRECIP WATERS
APPROACHING 2 INCHES (~+1.5 STD DEV). THE RESULT WILL BE
WIDESPREAD MODERATE TO HEAVY RAINFALL. HAVE INCREASED POPS TO
CATEGORICAL FOR THIS AFTERNOON ACROSS MUCH OF THE FA. DO NOT
ANTICIPATE A FLOOD WATCH AS SYSTEM REMAINS PROGRESSIVE AND
ANTECEDENT CONDITIONS ARE NOT FAVORABLE FOR WIDESPREAD
FLOODING...BUT SOME LOCALIZED FLOODING IN HEAVIEST SHOWERS IS
PROBABLE. WHILE INSTABILITY WILL BE RATHER WEAK OVER CNTRL
VA...CANNOT RULE OUT OCCASIONAL THUNDER...WHICH COULD LEAD TO HIGHER
RAINFALL RATES. ACROSS SE VA/NE NC...BETTER MOISTURE/INSTABILITY
WILL RESULT IN BETTER CHANCES FOR CONVECTION OUT IN ADVANCE OF THE
SHOWERS. THETA-E ADVECTION AND TEMPS WARMING INTO THE MID
80S/DEWPOINTS IN THE LOW 70S WILL MAINTAIN A MARGINALLY UNSTABLE
AIRMASS (0-6KM MUCAPE 1000-1200 J/KG). STEEP LOW LEVEL LAPSE RATES
WILL PROVIDE THE OPPORTUNITY FOR STRONG WINDS UP TO 40 MPH UNDER
THE STRONGEST STORMS. WEAK SHEAR WILL PREVENT OVERALL ORGANIZED
CONVECTION. LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE.

COLD FRONT AND SFC LOW WILL CROSS THE REGION LATE
AFTERNOON...PUSHING OFFSHORE THIS EVENING. RICH MOISTURE WILL ALSO
PUSH OFFSHORE. THE SECOND SHORTWAVE WILL DIG OVER THE OH VALLEY
INTO THE MID ATLANTIC REGION BY WEDS MORNING. REMNANT MOISTURE AND
FORCING FOR ASCENT PROVIDED BY THE SHORTWAVE WILL RESULT IN POST
FRONTAL SCATTERED SHOWERS TONIGHT...MAINLY ACROSS ERN VA AND NERN
NC.

HIGHS TODAY WILL RANGE FROM THE LOW 80S NW (EARLY AFTERNOON
BEFORE COOLING THROUGH THE AFTERNOON DUE TO RAINFALL) TO MID 80S
SE. MILD TONIGHT WITH LOWS GENERALLY IN THE UPPER 60S. CLEARING
SKIES OVER THE PIEDMONT WILL RESULT IN SLIGHTLY COOLER TEMPS
TONIGHT.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
LO PRES TRACKS OFF THE CST TNGT W/ CDFNT SETTLING S INTO THE
CAROLINAS. CHCS FOR HEAVY RAIN DCRS AFT MDNGT...THOUGH KEEPING
POPS MNLY BTWN 30-50%. WNDS BECOME N OVRNGT...THOUGH DRYING WILL
BE LMTD. SFC HI PRES FM THE N WILL BE SLO TO BUILD INTO THE RGN ON
WED. TSECTIONS SHOWING CONTD MOISTURE IN LO LVLS AND W/ NNE
FLO...CLRG LIKELY TO BE SLO/GRADUAL. POPS MNLY 20% N TO 30% ACRS
THE SRN VA/NE NC.

SFC HI PRES AND DRY AIR EXPAND TO THE SSE WED NGT THROUGH THU
RESULTING IN CLRG AND COOLER CONDS. MDLS (ESP THE GFS) DO SUGGEST
PTNTL FOR DIURNAL CNVTN THU OVR THE HIGHER TERRAIN...MNLY W OF THE
FA.

LO TEMPS TNGT FM THE M60S TO ARND 70F. HI TEMPS WED FM THE M70S AT
THE CST TO ARND 80F INLAND. LO TEMPS WED NGT FM THE U50S TO M60S.
HI TEMPS THU FM ARND 80F AT THE CST TO THE M80S INLAND.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A RATHER BENIGN PATTERN IS EXPECTED LATE THIS WEEK THROUGH THE
WEEKEND INTO EARLY NEXT WEEK AS HIGH PRESSURE SLOWLY DROPS S OFF THE
MID-ATLANTIC COAST. THERE IS VERY LITTLE POTENTIAL FOR
SHOWER/THUNDERSTORM DEVELOPMENT DUE TO A LACK OF LARGE SCALE FORCING
AND ANY SURFACE FOCUSING MECHANISMS. A GENERAL SHIFT OF THE
LOW-LEVEL FLOW FROM SE-SW WILL PRODUCE A STEADY WARMING TRENDS WITH
HIGHS RISING FROM THE LOW TO MID 80S FRIDAY...TO THE UPPER 80S TO
LOW 90S BY MONDAY. LOW TEMPERATURES SHOULD TREND UPWARD FROM 60-65
EARLY IN THE PERIOD TO THE UPPER 60S/LOW 70S LATE IN THE PERIOD.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
LO PRES AND A COLD FRONT WILL AFFECT THE REGION TODAY THRU WED
MORNG. MVFR/IFR CIGS WILL BE POSSIBLE THRU THIS MORNG...DUE TO SSW
FLO CAUSING SOME FOG AND/OR STRATUS. THAT LO PRES AREA AND COLD
FRONT WILL PRODUCE ANOTHER ROUND OF SHOWERS AND TSTMS OVR THE
REGION...ESPLY FM LATER THIS MORNG INTO EARLY WED MORNG. A BRIEF
REDUCTION TO CIGS/VSBYS SHOULD BE EXPECTED UNDER HEAVIER SHOWERS
OR STRONGER STORMS. MAINLY VFR CONDITIONS SHOULD RETURN FOR LATER
WED THRU THU...AS HI PRES BLDS INTO THE AREA THEN OFF THE NRN MID
ATLC CST.

&&

.MARINE...
EARLY THIS MORNG...A COLD FRONT WAS DROPPING INTO OH AND
PA...WHILE LO PRES WAS MOVNG INTO W/CNTRL TN. THE COMBINATION OF
THESE TWO SYSTEMS WILL MOVE ACRS THE AREA LATER TODAY THRU WED
MORNG. SSW WINDS LESS THAN 15 KT DURING TODAY...WILL SHIFT TO THE
NNE FM N-S LATE TNGT INTO WED MORNG...THEN REMAIN NE INTO THU...AS
HI PRES BLDS OVR NEW ENGLAND AND LO PRES LINGERS OFF THE CST. WILL
KEEP CONDITIONS BELOW SCA CRITERIA FOR NOW...ESPLY OVR THE CHES
BAY...WHILE ONSHR FLO HAS THE POTENTIAL TO BLD SEAS TO 5 FT WED
INTO WED NGT. THE HI SLOWLY SINKS S OFF THE CST LATE IN THE WEEK
INTO NEXT WEEKEND...WITH THE WIND VEERING FM NE-S AND REMAINING
AOB 15 KT.

&&

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

&&

$$
SYNOPSIS...ALB
NEAR TERM...SAM
SHORT TERM...ALB
LONG TERM...AJZ
AVIATION...TMG
MARINE...TMG