-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 150815
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
415 AM EDT TUE APR 15 2014

.SYNOPSIS...
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A STRONG COLD FRONT WILL CROSS THE AREA TODAY...THEN MOVE OFF THE
COAST THIS EVENING. CANADIAN HIGH PRESSURE BUILDS IN FROM THE
NORTHWEST TUESDAY NIGHT AND SETTLES OVER THE MID ATLANTIC AND
NORTHEAST WEDNESDAY AND THURSDAY.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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LITTLE CHANGE COMPARED TO PREVIOUS FORECASTS AS A STRONG COLD
FRONT IS SET TO IMPACT THE REGION THIS AFTERNOON.

REST OF THIS MORNING...
LATEST WATER VAPOR IMAGERY AND UPPER AIR
RAOB PLOTS DEPICT ANOMALOUS LONGWAVE TROUGH OVER THE CENTRAL
CONUS...SLOWLY PROGRESSING EWD. ASSOCIATED COLD FRONT IS
STRETCHING FROM THE OH VALLEY SWD INTO THE LOWER MS VALLEY/NRN
GULF. ALSO VISIBLE ON WATER VAPOR IS A PLUME OF MOISTURE FROM THE
NRN GULF NEWD INTO NEW ENGLAND...THANKS TO DEEP LAYER SWLY FLOW.
PER BLENDED TOTAL PRECIP WATERS...PRECIP WATER VALUES HAVE REACHED
200+ PCT OVER THE LOCAL AREA. UPSLOPE FLOW AND ANOMALOUS MOISTURE
HAS RESULTED IN WIDESPREAD PRECIP OVER THE CNTRL
APPALACHIANS...WITH MOST OF THE PRECIP STAYING TO THE WEST OF OUR
ERN VA PIEDMONT COUNTIES. ANOTHER AREA OF UPGLIDE ALONG THE COAST
HAS PRODUCED SCT SHOWERS FROM ELIZABETH CITY NWD TO SALISBURY.
ANOTHER AREA OF SHOWERS OVER S CNTRL NC WILL LIKELY LIFT OVER THE
PIEDMONT INTO CNTRL VA EARLY THIS MORNING...AIDED STRONG UPPER
LEVEL SUPPORT.

FOR TODAY...
STRONG SPEED MAX EMERGING FROM THE BASE OF THE UPPER TROUGH WILL
EJECT THE TROUGH NEWD TODAY. THIS WILL RESULT IN THE TROUGH
BECOMING NEGATIVELY TILTED AS IT LIFTS OVER THE MID-ATLANTIC
REGION. COLD FRONT PROGGED TO REACH THE LOCAL AREA LATE MORNING-
EARLY AFTERNOON. MODELS HAVE A GOOD HANDLE ON THE TIMING OF THE
FRONT...PUSHING IT THRU THE LOCAL AREA THIS AFTERNOON AND OFFSHORE
THIS EVENING. STRONG HEIGHT FALLS AND A SHARP TEMPERATURE CONTRAST
WILL RESULT IN STRONG FRONTOGENETIC FORCING ALONG THE FRONT. RRQ
OF 160+KT UPPER JET AND VORTICITY ADVECTION WILL PROVIDE STRONG
UPPER LEVEL FORCING FOR ASCENT ALONG THE FRONT. INCREASING WINDS
ALOFT WILL ALSO RESULT IN A STRONG LLJ...WITH 850 WINDS 50-60 KT
(+3 TO +4 STD DEV). THE RESULT IS A FAVORABLE SYNOPTIC SETUP.
INSTABILITY WILL BE RATHER LIMITED...BUT THETA-E ADVECTION AND
TEMPS IN THE MID-UPPER 70S WILL PRODUCE A MARGINALLY UNSTABLE
AIRMASS (MLCAPE 500-750 J/KG) DESPITE CLOUD COVER. THE EXCEPTION
WILL LIKELY BE OVER THE PIEDMONT WHERE RAINFALL WILL FURTHER LIMIT
INSTABILITY. 0-3KM BULK SHEAR OF 50-60 KT WILL LIKELY RESULT IN
ANY DEVELOPING CONVECTION TO ORGANIZE INTO LINE SEGMENTS...WITH
SOME BOWING SEGMENTS POSSIBLE. THIS WILL LEAD TO AN ENHANCED
THREAT FOR DAMAGING WINDS IN EXCESS OF 50 KT THANKS TO STRONG LLG.
LATEST NAM/SREF/ECMWF GUIDANCE INDICATE A WAVE DEVELOPING ALONG
THE FRONT OVER CNTRL NC EARLY THIS AFTERNOON...LIFTING INTO NE
NC/POSSIBLE SE VA. IF THIS OCCURS...THIS WOULD INCREASE LOW LEVEL
HELICITY...WITH ISOLATED WEAK TORNADOES POSSIBLE IN BROKEN LINE
SEGMENTS. MUCH OF THE LOCAL AREA REMAINS UNDER A SLIGHT RISK FOR
SEVERE WEATHER. BEST CHANCES FOR SEVERE WEATHER WILL BE MID-LATE
AFTERNOON ALONG THE IMMEDIATE FRONT AS IT REACHES INTERSTATE 95
AND POINTS EWD. THE EXCEPTION WILL BE THE MD/VA ERN SHORE WHERE A
MARINE ENVIRONMENT WILL LIMIT SEVERE POTENTIAL. ANOMALOUS MOISTURE
AND STRONG DYNAMICS WILL ALSO RESULT IN PERIODS OF HEAVY RAINFALL.

COLD FRONT MAY SLOW SLIGHTLY AS IT REACHES THE COAST...BUT WILL
PUSH OFFSHORE EARLY THIS EVENING...WITH PRECIP ENDING SHORTLY
THEREAFTER. TOTAL QPF AMOUNTS WILL RANGE FROM 1-1.5 INCHES. THE
IMPACT THEN BECOMES INCREASING NW WINDS AND THE ASSOCIATED COLD
AIR SURGING INTO THE REGION. SKIES WILL ALSO BEGIN TO CLEAR
QUICKLY W-E AS THE BEST MOISTURE QUICKLY PUSHES OFFSHORE AND THE
TROUGH LIFTS NE OF THE REGION.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
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RAIN ENDS IN THE SOUTHEAST TUESDAY NIGHT WITH CLEARING SKIES FROM
W TO E OVERNIGHT. TEMPERATURES ARE FORECAST TO DROP TO 30 TO 35
WELL INLAND TO NEAR 40 IN THE SOUTHEAST. FUTURE ISSUANCES MAY
REQUIRE FREEZE HEADLINES IN COUNTIES WEST OF INTERSTATE 95 IF
CONFIDENCE IS HIGH ENOUGH THAT 3 HOURS OF 32 OR BELOW WILL OCCUR.
IT APPEARS THAT MODEL GUIDANCE IS TOO LOW WITH THEIR NUMBER. AT
THIS POINT...IT APPEARS MARGINAL. FROST IS NOT AN ISSUE DUE TO THE
WIND.

WEDNESDAY THROUGH THURSDAY WILL HAVE A CLEAR TO PARTLY CLOUDY SKY.
MOST OF THE CLOUDS WILL BE IN THE SOUTHEAST. THERE IS A POSSIBILITY
FOR LIGHT RAIN NEAR THE NORTH CAROLINA COAST BY THURSDAY BUT KEPT
FORECAST DRY FOR NOW. TEMPERATURES AGAIN MAY FALL TO AROUND FREEZING
OVER INLAND COUNTIES WITH THE MODEL GUIDANCE POSSIBLY TOO HIGH. WILL
ASSESS AS WE GET CLOSER. TEMPERATURES WEDNESDAY AND THURSDAY ARE
FORECAST TO TOP OFF GENERALLY IN THE 50S.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
STRONG SFC HIGH PRESSURE REMAINS ANCHORED OVER NEW ENGLAND TO
BEGIN THE MEDIUM RANGE FORECAST PERIOD, RESULTING IN CONTINUED NE
FLOW OVER THE MID ATLANTIC FRIDAY. TEMPERATURES WILL BE COOL TO
BEGIN THE PERIOD FRIDAY...ABOUT ONE STANDARD DEVIATION BELOW
NORMAL...WITH TEMPS MODERATING A BIT SATURDAY. ALOFT, NORTHERN
STREAM SHORTWAVE TROUGH, AND ATTENDANT SFC LOW IS EXPECTED TO PUSH
ACROSS THE MID MS VLY TOWARDS THE EASTERN GREAT LAKES FRI-SAT,
EVENTUALLY PUSHING A MAINLY DRY COLD FRONT THROUGH SAT NGT AND
EARLY SUNDAY. BOTH MODELS DO TAKE A PIECE OF SHORTWAVE ENERGY
ACROSS THE MID-SOUTH TOWARDS THE CAROLINA COAST FRIDAY-SATURDAY,
WITH RESULTANT WEAK INVERTED TROUGHING THAT DEVELOPS PROMPTING
SOME LOW POPS LATER FRIDAY AND SATURDAY. THE 12Z/14 EURO SOLUTION
REMAINS A BIT WETTER THAN THE PROGRESSIVE GFS SOLUTION. HAVE SPLIT
THE DIFFERENCE BETWEEN THE GFS/UKMET FOR THIS PACKAGE. RIGHT NOW,
IT APPEARS THAT THE BEST RAIN CHC WOULD BE OVER EASTERN SECTIONS
ALONG THE COASTAL TROUGH FRIDAY NIGHT THROUGH MIDDAY SATURDAY.
UPPER TROUGH EJECTS NORTHEAST LATER SATURDAY, WITH SHORTWAVE
RIDGING ARRIVING FROM THE WEST SHUNTING SYSTEM OFFSHORE. QUICK
CLEARING EXPECTED THEREAFTER TOWARDS THE TAIL END OF THE PERIOD
(EASTER SUNDAY AND MONDAY).

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS ACROSS AREA TERMINALS EARLY THIS EVENING. WINDS
CONT TO BE BREEZY 15-25 KT. A FEW SPOTTY SPRINKLES ACROSS THE
REGION WITH THE HEAVIER PRECIP STILL WEST AND SOUTH OF THE CWA.
EXPECT CHANCE OF RAIN TO INCREASE AFTER MIDNIGHT AS FRONT
APPROACHES. CIGS SLOWLY DETERIORATE TO MVFR TONIGHT...W/PERIODIC
IFR CIGS POSSIBLE TOWARDS SUNRISE AS MOISTURE ADVECT IN ADVANCE OF
THE FRONT. BREEZY SOUTHERLY WINDS CONTINUE TUESDAY (GUSTS OF 30-35
KT) AS THE FRONT APPROACHES FROM THE WEST. COLD FRONT CROSSES THE
REGION TUESDAY, ACCOMPANIED BY WIDESPREAD RAINFALL TUES-TUES NIGHT
WITH PERIODIC IFR VSBY RESTRICTIONS IN HEAVY RAIN. THERE IS ALSO
THE POTENTIAL FOR A STRONG LINE OF CONVECTION ON THE LEADING EDGE
OF THE FRONT TUES AFTERNOON MAINLY ACROSS SOUTHEASTERN TERMINALS
(PHF-ORF- ECG)W/ HEAVY RAIN AND STRONG WIND GUSTS UP TO 50 KT
POSSIBLE.

OUTLOOK...BEHIND THE FRONT, LOOK FOR WINDS TO BACK TO THE NW AND
REMAIN GUSTY. SOME GUSTS UP TO 40 KT POSSIBLE ALONG THE COAST.
IMPROVING CONDITIONS WED THRU FRIDAY AS HIGH PRESSURE BUILDS INTO
THE REGION FROM THE NORTH.

&&

.MARINE...
STRONG COLD FRONT WILL APPROACH FM THE W TNGT...THEN PUSH ACRS
THE AREA TUE INTO TUE EVENG. DECENTLY STRNG SOUTHERLY WINDS IN
ADVANCE OF THE FRONT TNGT THRU TUE...WILL BECOME VERY STRONG N
WINDS BEHIND THE FRONT TUE NGT THRU MUCH OF WED...AS A MUCH
COLDER/DRIER AIRMASS FILTERS INTO THE AREA. DURING THIS
EVENT...WAVES WILL BLD TO 4 TO 6 FT OVR THE CHES BAY...AND SEAS
WILL BLD TO 5 TO 9 FT ON THE CST. HI PRES WILL THEN BLD JUST TO
THE N WED AFTN...THEN SLIDES NE ACRS NEW ENGLAND AND INTO THE
CANADIAN MARITIMES WED NGT THRU THU. THIS WILL RESULT IN NE WINDS
AND ELEVATED SEAS THRU THE END OF THE WEEK.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR MDZ021>024.
NC...FREEZE WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR
     NCZ012.
VA...FREEZE WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR
     VAZ078-084>090-092-093.
     FREEZE WARNING FROM 3 AM TO 9 AM EDT WEDNESDAY FOR VAZ048-049-
     060>077-079>083.
MARINE...GALE WARNING UNTIL 1 PM EDT WEDNESDAY FOR ANZ650-652-654-656-
     658.
     GALE WARNING FROM 8 AM THIS MORNING TO 7 AM EDT WEDNESDAY FOR
     ANZ635>638.
     GALE WARNING UNTIL 7 AM EDT WEDNESDAY FOR ANZ630>632-634.
     GALE WARNING FROM 8 AM THIS MORNING TO 1 PM EDT WEDNESDAY FOR
     ANZ633.
-- End Changed Discussion --

&&

$$
SYNOPSIS...LSA
NEAR TERM...SAM
SHORT TERM...MPR/LSA
LONG TERM...MAM/JEF
AVIATION...JEF
MARINE...TMG