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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 232321
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
721 PM EDT WED APR 23 2014

.SYNOPSIS...
COOL CANADIAN HIGH PRESSURE SLOWLY BUILDS IN FROM THE NORTHWEST
OVERNIGHT. HIGH PRESSURE THEN SLIDES OVER THE REGION INTO THURSDAY
MORNING...LOCATING OFF THE SOUTHEAST COAST THURSDAY AFTERNOON. A
SERIES OF WEAK FRONTS WILL CROSS THE AREA FRIDAY INTO THE WEEKEND.
A PERIOD OF UNSETTLED WEATHER IS EXPECTED OVER THE AREA EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
UPPER TROUGH AXIS HAS SHIFTED OFFSHORE PER LATEST WATER VAPOR
IMAGERY...AS SFC HIGH PRESSURE BUILDS SWD FROM THE GREAT LAKES
REGION. THE RESULT WILL BE CLEAR SKIES OVERNIGHT AND DECREASING NW
WINDS. WITH THE HIGH PRESSURE TO THE WEST OF THE AREA...ANOTHER
ROUND OF CAA OVERNIGHT WILL PUSH TEMPS INTO THE MID-UPPER 30S
INLAND AND INTO THE LOW 40S NEAR THE COAST. WINDS WILL NOT
COMPLETELY DE-COUPLE TONIGHT...RANGING FROM 5-10 MPH INLAND TO 10
TO 15 NEAR THE COAST. COMBINE LIGHT MIXING WITH RATHER DRY GROUND
CONDITIONS AND LOW DEWPOINTS...DO NOT ANTICIPATE WIDESPREAD FROST
AND WILL LEAVE OUT OF GRIDS. HOWEVER...PATCHY FROST IS POSSIBLE IN
SHELTERED LOCALES.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
SFC HIGH PRESSURE CENTERS OFF THE SE COAST THURS AS AN UPPER
RIDGE BUILDS OVER THE ERN CONUS. UPPER TROUGH OVER THE
INTERMOUNTAIN WEST WILL DE-AMPLIFY AND EJECT NEWD INTO THE PLAINS
THURS...PUSHING AN ASSOCIATED COLD FRONT INTO THE MS VALLEY. FLOW
RETURNS TO THE SOUTH LATE THURS-THURS NIGHT AS A WARM FRONT LIFTS
OVER THE REGION. MID-LEVEL WLY FLOW OVER THE GULF STATES INTO THE
MID-ATLANTIC WILL PREVENT MUCH OF A MOISTURE RETURN INTO THE
REGION....SO DRY CONDITIONS WILL PREVAIL. NWLY WINDS WILL NOT BE
AS STRONG THURS AFTERNOON...BUT MIN RH VALUES IN THE UPPER TEENS-
LOW 20S AND DRY FUELS WILL AGAIN RESULT IN POTENTIAL FIRE WX
CONCERNS. PLEASE REFER TO FIRE WEATHER SECTION BELOW FOR MORE
INFORMATION.

RIDGE AXIS PUSHES OFFSHORE FRI MORNING AS THE UPPER WAVE REACHES
THE OH VALLEY. QUESTIONS STILL EXIST ON STRENGTH OF THE UPPER WAVE
AS IT CROSSES THE MID-ATLANTIC REGION FRI AFTERNOON...WITH THE
LATEST GFS TRENDING SHARPER THAN ITS PREVIOUS RUNS AND COMING
MORE IN LINE WITH ITS NAM/ECMWF COUNTERPARTS. COLD FRONT WILL PUSH
ACROSS THE REGION FRI AFTERNOON-EVENING. SHORT LIVED LOW-LEVEL SW
FLOW WILL BE ABLE TO ADVECT MODEST PRECIP WATER VALUES OF 1-1.25
INCHES INTO THE REGION...BUT DEWPOINTS ONLY PROGGED TO WARM INTO
THE UPPER 40S TO NEAR 50 FRI. WITH THE LOCAL AREA IN THE WARM
SECTOR FRI...TEMPS WILL WARM INTO THE UPPER 70S TO NEAR 80
(DEPENDING ON FRONTAL TIMING). COMBINATION OF WARM TEMPS AND
THETA-E ADVECTION WILL RESULT IN A MARGINALLY UNSTABLE AIRMASS
(MLCAPE <500 J/KG)...MOSTLY OVER ERN VA/NERN NC. ALSO...LITTLE
INSTABILITY/LIFT PROGGED IN THE MIXED PHASE LAYER SO ANTICIPATE
ONLY ISOLATED/SLIGHT CHANCE THUNDER IN CONVECTION. JUST LIKE
YESTERDAYS FRONT...BIGGEST LIMITATIONS ARE WSW FLOW AND LOW
DEWPOINTS. SHEAR IS ALSO MARGINAL (~30-35 KT) SO DO NOT ANTICIPATE
ORGANIZED CONVECTION ALONG THE WEAKLY FORCED FRONT. WITH THAT
SAID...WILL MAINTAIN CHANCE POPS OVER THE REGION FRI AFTERNOON
ALONG/BEHIND THE FRONT. QPF AMOUNTS WILL GENERALLY BE LESS THAN
ONE TO TWO TENTHS.

FRONT PUSHES OFFSHORE FRI NIGHT AS A SECONDARY DRY COLD FRONT
ASSOCIATED WITH AN UPPER LOW OVER THE GREAT LAKES APPROACHES FROM
THE NW. BREEZY WLY/DOWNSLOPE FLOW SAT AND INCREASING LOW LEVEL
THICKNESS VALUES WILL RESULT IN DAYTIME TEMPS AROUND 80 DEGS MOST
LOCALES...EVEN BEHIND FRIDAYS FRONT. NARROW BAND OF MOISTURE AND
MEASURABLE PRECIP FORECAST TO REMAIN NORTH OF THE LOCAL AREA LATE
SAT-SAT EVENING.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
MODELS CONTINUE TO POINT TO A HIGHLY AMPLIFIED/BLOCKY PATTERN OVER
THE CONUS NEXT WEEK...RESULTING IN AN INCREASINGLY WET PERIOD.

MODELS CONTINUE TO STRUGGLE WITH THIS BLOCKY FLOW...MAINLY IN
LOCATION OF FRONTAL BOUNDARY PROGGED TO BE DRAPPED ACROSS THE RGN
ALONG WITH TIMING OF SEVERAL BATCHES OF MSTR PROGGED TO ROTATE NE
FROM THE DEEP SOUTH. WHAT TODAYS MODELS SHOW DIFFERENT FROM YSTRDYS
IS A SLOWER START TO THE PCPN MON...SOMEWHAT HIGHER CONFIDENCE FOR
AN EXTNDD PRD OF WETNESS FROM MON NITE THRU WED ALONG WITH A FRONTAL
BOUNDARY THAT WILL LIKELY PLAY HAVOC WITH TEMPS.

KEPT SUN DRY / SEASONABLE AS H5 RIDGE BUILDS ACROSS THE AREA. WARM
FRONT APPRCHS THE RGN FROM THE SW SUN NIGHT...BUT GUID SUGGESTS ANY
MOISTURE STAYS W OF FA THRU 12Z MON. LOWS SAT / SUN NIGHTS IN THE
M40S-L50S. HIGHS SUN 70-75 WEST OF THE BAY...M-U60S ALONG THE COAST.

FORECAST RATHER PROBLEMATIC NEXT WEEK AS THE MODELS DIFFER ON WHERE
THIS FRONTAL BNDRY SETS UP. THIS WILL LIKELY DETERMINE TMPS AND PCPN
TYPES (CONVECTIVE VS STRATIFORMED RAIN). UPR LVL LOW PROGGED TO
SLOWLY EJECT EAST FROM THE NATIONS MID SECTION MON NIGHT ONLY TO THE
OHIO VLLY BY WED. A MOIST E-SE FLOW WILL LIKELY ADD TO THE MOISTURE
CONTENT RESULTING IN PERIODIC CHCS FOR PCPN THRU THE PRD. FRNTL
BNDRY MAY ALSO TRY TO MAKE A RUN FARTHER NORTH BY WED AS SFC LOW
BEGINS TO CROSS THE MTS. TRAILING COLD FRONT WILL EVENTUALLY PUSH
ALL THIS OUT TO SEA...BUT THAT MIGHT NOT BE UNTIL THURSDAY. UPSHOT
WILL CARRY HIGH CHC POPS (SHWRS) MON THROUGH WED. TMPS COOLEST
(L-M60S) ALONG THE COAST DUE TO AN ONSHORE FLOW. HIGHS U60S-L70S
WEST OF THE BAY. LOWS IN THE 50S.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
AS THE FRONT CONTINUES TO PUSH FARTHER OFF SHORE...THE PRESSURE
GRADIENT WILL TIGHTEN UP NEAR THE IMMEDIATE COAST WHERE WNW-NW
WINDS SHOULD AVERAGE CLOSE TO 20G30KT BEFORE TAPERING OFF DURING
THE EVENING AND OVERNIGHT HOURS. NW WIND SPEEDS BRIEFLY INCREASE
THU MORNING AND THEN DROP OFF THROUGH THE AFTN AS HIGH PRESSURE
SLIDES ACROSS THE AREA AND BECOMES LOCATED OFF THE SOUTHEAST COAST
BY THU EVENING.

THE NEXT COLD FRONT APPROACHES THE REGION THU NIGHT...CAUSING NW
WINDS TO BACK AROUND TO THE S-SE. THE FRONT IS EXPECTED TO CROSS
THE MID ATLANTIC REGION FRI EVENING...BRINGING SHOWERS AND A
SLIGHT CHANCE FOR THUNDERSTORMS TO AREA TAF SITES. BEHIND THIS
FRONT...WINDS WILL GENERALLY BE NLY AROUND 15 KT OR LESS THROUGH
THE REST OF THE WEEKEND.

&&

.MARINE...
MIXING STILL PRODUCING GUSTY WINDS LATE THIS AFTRN ACROSS THE WATERS.
EXPECT WINDS OVER THE RIVERS AND CURRITUCK SOUND TO SLOWLY DMNSH NXT
FEW HRS...SO SCA WILL CONTINUE THRU 7 PM THERE....10 PM FOR LWR JAMES
IVOF ORF. SECONDARY SURGE NOTED IN MODELS KEEPS SCA HEADLINES FOR
CHES BAY / CSTL WTRS INTO WED MORNING. 25-30 KT GUSTS PSBL AS WELL.

HIGH PRS BUILDS INTO THE AREA WED AFTRN THEN SHIFTS OFFSHORE WED
NITE AND THURSDAY. THIS RESULTS IN DMNSH WINDS AND IMPROVING SEAS.
THUS...SCA`S WILL GRADUALLY END WED...LATEST OVR COASTAL WATERS
WHERE IT MAY TAKE SEAS A FEW HRS LONGER TO DROP BLO 5 FT. SE FLOW
BECOMES S THEN SW AS BY FRI AS RETURN FLOW ESTABLISHES ITSELF ON
BACK SODE OF RETREATING HIGH.

NEXT FRNT PROGGED ACROSS THE RGN FRI NIGHT WITH A SECONDARY TROF
CROSSING THE WATERS SAT. EXPECT CONDITIONS TO REMAIN BLO SCA LEVELS
THROUGH SAT...ALTHOUGH ANOTHER WEAKER NW SURGE IS PSBL SAT AFTRN.

&&

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

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MD...INCREASED FIRE DANGER FROM THURSDAY MORNING THROUGH THURSDAY
     EVENING FOR MDZ021>025.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THURSDAY FOR ANZ630>632-
     634.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ638.
     SMALL CRAFT ADVISORY UNTIL 4 PM EDT THURSDAY FOR ANZ650-652-
     654-656-658.
-- End Changed Discussion --

&&

$$
SYNOPSIS...SAM
NEAR TERM...JDM/SAM
SHORT TERM...SAM
LONG TERM...MPR
AVIATION...DAP
MARINE...MPR
FIRE WEATHER...JDM