Area Forecast Discussion
Issued by NWS Wakefield, VA

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000
FXUS61 KAKQ 242001
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
401 PM EDT THU APR 24 2014

.SYNOPSIS...
HIGH PRESSURE SLIDES OFFSHORE TONIGHT. LOW PRESSURE TRACKS FROM THE
OHIO VALLEY ACROSS THE NORTHERN MID ATLANTIC FRIDAY...AND OFF THE
COAST FRIDAY NIGHT. A COLD FRONT DROPS ACROSS THE REGION SATURDAY
NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
CURRENT WV IMAGERY INDICATES AN UPPER TROUGH STEADILY TRACKING W-E
ACROSS THE CENTRAL PLAINS...WITH ANOTHER TROUGH DOWNSTREAM OF THE
LOCAL AREA OVER ATLANTIC CANADA. A NARROW RIDGE AXIS EXISTS OVER THE
SOUTHEAST AND OHIO VALLEY...WITH SURFACE HIGH PRESSURE UNDERNEATH
THIS FEATURE EXTENDING FROM THE EASTERN GREAT LAKES THROUGH THE MID
ATLANTIC.

THE CENTRAL PLAINS TROUGH WILL LIFT NE THROUGH THE MID MISSISSIPPI
VALLEY TOWARD THE GREAT LAKES OVERNIGHT. MEANWHILE...SURFACE HIGH
PRESSURE WILL SLIDE OFFSHORE. THE SKY SHOULD BE MAINLY CLEAR THROUGH
THE EVENING AND EARLY OVERNIGHT HOURS...BEFORE CLOUDS BEGIN TO
INCREASE OVER WESTERN PORTIONS LATE. THE TEMPERATURE SHOULD DROP
QUICKLY THROUGH THE EVENING HOURS...WITH COOL DRY HIGH PRESSURE OVER
THE AREA...AND BECOME STEADY AFTER MIDNIGHT. LOWS SHOULD RANGE FROM
THE UPPER 30S TO LOW 40S OVER INTERIOR PORTIONS E OF I-95...WITH
LOW/MID 40S W DUE TO INCREASED MIXING (FROM LIGHT SE FLOW) AS THE
HIGH SHIFTS OFFSHORE AND THE APPROACH OF LOW PRESSURE FROM THE W.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
THE PARENT TROUGH LIFTS THROUGH THE GREAT LAKES FRIDAY...WITH
SURFACE LOW PRESSURE TRACKING ACROSS THE NORTHERN MID-ATLANTIC. A
PROMINENT (SURFACE AND MID-LEVEL) THETA-E RIDGE PRECEDES THE TROUGH
AXIS. THIS SHOULD PRODUCE AN INCREASE IN BOUNDARY LAYER MOISTURE
THROUGH THE MORNING. FORECAST SOUNDINGS SHOW A PERIOD OF RATHER DEEP
MOISTURE ALONG WITH A PERIOD OF MODEST LIFT PASSING ACROSS THE LOCAL
AREA LARGELY IN THE 18-00Z TIMEFRAME. GIVEN THIS THERE IS HIGH
CONFIDENCE OF SHRA AND EMBEDDED TSRA PASSING ACROSS THE AREA. THE
BEST DESTABILIZATION OCCURS OVER SE PORTIONS. THIS WILL BE IN THE
PRESENCE OF MODEST DEEP LAYER SHEAR (~35KT 0-6KM)...AND ~30KT OF
0-1KM BULK SHEAR. AT THIS TIME INSTABILITY APPEARS TOO MARGINAL TO
SUPPORT ORGANIZED SEVERE WEATHER...BUT THERE IS ENOUGH SHEAR FOR A
MINIMAL THREAT MAINLY ACROSS FAR SE VA/NE NE. HIGHS SHOULD GENERALLY
BE IN THE LOW/MID 70S (LOCALLY COOLER ALONG THE COASTS).

THE MID-LEVEL COLD FRONT (COLD THETA-E BOUNDARY) MOVES OFF THE COAST
LATE FRIDAY NIGHT...WITH DRIER AIR ARRIVING FROM THE W. THE SURFACE
BOUNDARY IS MAINLY A WIND SHIFT...SO TEMPERATURES SATURDAY SHOULD
GENERALLY BE A FEW DEGREES WARMER THAN FRIDAY. HIGHS ARE EXPECTED TO
RANGE FROM THE MID 70S OVER EASTERN PORTIONS (LOCALLY COOLER ALONG
THE IMMEDIATE COAST)...TO AROUND 80 ALONG A W OF I-95. THIS WILL BE
AFTER MORNING LOWS RANGING FROM THE UPPER 40S NW...TO UPPER 50S SE.

SATURDAY SHOULD BEGIN MOSTLY SUNNY...BEFORE CLOUDS INCREASE
(ESPECIALLY N) AHEAD OF A COLD FRONT APPROACHING FROM THE NW. AT
THIS TIME POPS WILL BE HELD BELOW 15%...BUT A FEW SPRINKLES ARE
POSSIBLE ACROSS THE FAR NORTHERN PORTIONS. THIS FOLLOWS MORE OF A
12Z GFS/ECMWF SOLUTION RATHER THAN THE MORE MOIST 12Z NAM DUE TO THE
EXPECTATION OF LIMITED BOUNDARY LAYER MOISTURE.

THE COLD FRONT DROPS THROUGH THE AREA SATURDAY NIGHT...WITH HIGH
PRESSURE BUILDING IN FROM THE GREAT LAKES SUNDAY. LOWS SHOULD RANGE
FROM THE MID 40S TO LOW 50S SUNDAY MORNING...FOLLOWED BY HIGHS
SUNDAY AFTERNOON IN THE MID 60S NE TO LOW/MID 70S SW UNDER A MOSTLY
SUNNY/CLEAR SKY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A HIGHLY AMPLIFIED/BLOCKY PATTERN WILL RESULT IN AN UNSETTLED PRD
NEXT WEEK. TODAYS MODELS CONTINUE TO SLOW THE ARRIVAL OF PCPN UNTIL
MON AFTRN WHEN THE STALLED FRONTAL BNDRY ACROSS THE CAROLINAS BEGINS
TO MOVE BACK NORTH AS A WARM FRONT. KEPT SUNDAY NIGHT AND MON MORN
DRY AS HIGH PRS TO THE NORTH IS SLOW TO RETREAT. LOWS M40S-L50S.

MAIN UPR LEVEL LOW PROGGED TO SLOWLY EJECT EAST FROM NATIONS MID
SECTION MONDAY TO THE OHIO/TNN VLLY WED. MODELS CONTINUE TO SHOW A
SCNDARY LOW DVLPNG OVR THE MID ATLNTC REGION THURS WITH A TRAILING
COLD FRONT PUSHING DEEPEST MOISTURE OFFSHORE LATE THURSDAY FOLLOWED
BY LAGGING UPR LVL MOISTURE ACROSS THE AREA.

NUMEROUS FORECAST CHALLENGES DURING THIS PRD. PRIME OF WHICH WILL BE
THE LOCATION OF FRONTAL BOUNDARY NOW PROGGED TO HOVER SOMEWHERE ARND
THE NC/VA BORDER TUES THRU THURS. THE UNCERTAINTY HERE WILL MAKE
A PROBLEMATIC FORECAST FOR TMPS...WIND DIRECTION AND PCPN TYPE
(I.E. CONVECTIVE VS STRATIFORMED). BETTER CONFIDENCE TODAY THAT
THE TUES THRU WED TIME FRAME WILL BE THE WETTEST...SO HAVE
INCREASED TO LIKELY POPS THEN. OTW...KEPT PCPN SHOWERS CWA WIDE
FOR NOW GIVEN THE LOW CONFIDENCE THIS FAR OUT. COULD VRY WELL END
UP BEING MORE OF A STRATIFORMED RAINFALL ACROSS THE PIEDMONT IF A
COOL E-NE WEDGE SETS UP AS WELL AS HAVING TO ADD THUNDER TO THE
SOUTHERN ZONES GIVEN A FRONTAL BOUNDARY LOCATION FARTHER NORTH.
ALL-IN-ALL...EXPECT A COOL AND WET PRD. HIGHS GNRLLY FROM THE
L-M60S NORTHERN HALF OF FA TO U60S-L70S SOUTHERN HALF. LOWS U40S-
M50S.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS EXPECTED THROUGH THE 18Z TAF PERIOD FOR ALL AKQ
SITES. SURFACE HIGH PRESSURE BUILDING OVERHEAD ALONG WITH UPPER
LEVEL RIDGE HAS CREATED DRY AND MOSTLY CLEAR CONDITIONS ACROSS THE
MID-ATLANTIC. WINDS GUSTING TO NEAR 20 KT AT KSBY WILL SUBSIDE
AROUND 22/23Z AS THE PRESSURE GRADIENT WEAKENS TO THE NORTH.

AN AREA OF LOW PRESSURE AND ASSOCIATED COLD FRONT WILL BRING
SCATTERED SHOWERS AND A FEW THUNDERSTORMS FRIDAY AFTERNOON. BRIEF
PERIODS OF IFR WILL BE PSBL AT THE TAF SITES. HIGH PRESSURE BUILDS
INTO THE REGION DURING THE WEEKEND WITH A QUICK MOVING COLD FRONT
PASSING THROUGH THE AREA SAT NIGHT.

&&

.MARINE...
NO HEADLINES TONIGHT AND FRI MORNING AS HIGH PRS BUILDS OVER THE
WATERS. EXPECT VARIABLE WINDS TO BECOME S-SE BY MORNING. PRS GRDNT
INCREASES AHEAD OF APPRCHG COLD FRONT FRI. DATA SHOWING HIGHER
CONFIDENCE FOR AT LEAST MINIMAL SCA`S ACROSS THE CHES BAY FRI AFTRN.
FROPA FRI EVENING WITH A WIND SHIFT TO W-NW AFTR MIDNIGHT. ALTHOUGH
DATA SHOWS LITTLE IN THE WAY OF CAA...EXPECT A FEW HR PRD OF MINIMAL
SCA RIGHT BEHIND FROPA SO WILL KEEP SCA`S THROUGH THE NIGHT ACROSS
THE CHES BAY. OTW...EXPECT WINDS & SEAS TO STAY BLO SCA LVLS ACROSS
CSTL WTRS ATTM.

WEST WINDS ERLY SAT AHEAD OF A WEAK TROF PROGGED TO CROSS THE WATERS
SAT AFTRN. WIND SHIFT TO THE N BEHIND THIS FEATURE...BUT KEPT WINDS
BLO SCA LEVELS AS MOST MODELS PROGG WEAK ADVECTION BEHIND THIS FTR.
GFS SOMEWHAT STRONGER WITH ITS SURGE AND HAS WINDS INTO MINIMAL SCA
LEVELS SAT NITE. WILL TAKE A CLOSER LOOK AT THIS TOMORROW.

LARGE UPR LVL SYSTM XPCTD TO APPRCH THE AREA NEXT WEEK. ALTHOUGH
WINDS NOT THAT STRNG...WNA SHOWING INCRG SWELL WITH SEAS 5-7 FT BY
THE MIDDLE OF NEXT WEEK. HAVE SPLIT THE DIFFERENCE BUT INCRSD SEAS
TO 4-6 FT FOR NOW.

&&

.FIRE WEATHER...
DRY CONDITIONS (MIN RH VALUES 15-25%) WILL OCCUR AGAIN TODAY.
HOWEVER...WINDS WILL BE LIGHTER THAN WEDNESDAY. THIS WILL PRECLUDE
THE NEED FOR ANY RED FLAG WARNINGS OVER THE LOCAL AREA. NW WINDS
DO INCREASE TO AROUND 15 MPH WITH GUSTS OF 20-25 MPH DURING THE
LATE MORNING/EARLY AFTN HOURS ON THE LOWER MD/VA EASTERN SHORE.
GIVEN HOW LOW RH VALUES WILL BE THURSDAY AFTN COUPLED WITH LOW
FUEL MOISTURE CONDITIONS...HAVE CONTINUED THE INCREASED FIRE
DANGER STATEMENT FOR OUR MD COUNTIES (AFTER COORDINATION WITH MD
FIRE OFFICIALS) AND ADDED VA EASTERN SHORE COUNTIES TO THE
INCREASED FIRE DANGER STATEMENT.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...INCREASED FIRE DANGER UNTIL 6 PM EDT THIS EVENING FOR
     MDZ021>025.
NC...NONE.
VA...INCREASED FIRE DANGER UNTIL 6 PM EDT THIS EVENING FOR VAZ099-
     100.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM FRIDAY TO 4 AM EDT SATURDAY FOR
     ANZ630>632-634.

&&

$$
SYNOPSIS...AJZ
NEAR TERM...AJZ
SHORT TERM...AJZ
LONG TERM...MPR
AVIATION...DAP
MARINE...MPR
FIRE WEATHER...BMD




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