FXUS61 KAKQ 121025
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
525 AM EST FRI MAR 12 2010

.SYNOPSIS...
DEEP...ELONGATED LOW PRESSURE SYSTEM WILL GRADUALLY PUSH INTO THE
MID ATLANTIC REGION BY SATURDAY...THEN MOVE OFF THE COAST ON
SUNDAY. HIGH PRESSURE WILL GRADUALLY BUILD BACK ACROSS THE AREA
FROM THE WEST MONDAY THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INITIAL WIDESPREAD BAND OF RAIN CONTINUES TO LIFT NORTH EARLY THIS
MORNING...AS THE BULK OF THE ACTIVITY NOW SHIFTS INTO ERN VA AND
ESPECIALLY THE LOWER MD/VA ERN SHORE. PLENTY OF SUPPORTING
ELEMENTS AT PLAY HERE FOR THE WIDESPREAD...STEADY (OCNLY HEAVY)
RAINFALL...STARTING WITH THE WARM CONVEYOR BELT PRESENCE (DEEP
ISENTROPIC ASCENT) AND ELONGATED...DEEP E-SE LLVL FLOW WITH FETCH
ORIGINATION OFF THE GULF STREAM.

BY MID-MORNING...MOISTURE DEPTHS BECOME SHALLOWER (AS BACK EDGE OF
WCB SHIFTS OFF THE COAST)...THOUGH AXIS OF SUFFICIENTLY DEEP MOIST
ISENTROPIC ASCENT WILL LINGER ACROSS THE FCST AREA...PARTICULARLY
E OF I-95...TO MAINTAIN HIGH POPS THROUGH THE AFTN HOURS. THE
TRADE OFF TO THE CONTINUED HIGH PROBS WILL LIKELY BE A MORE
PERIODIC (SHOWERY) NATURE OF THE RAIN...I.E. NOT AS PERSISTENT OR
CONTINUOUS COMPARED TO THE OVERNIGHT HOURS AS THE INITIAL
(ELEVATED) WARM FRONTAL BNDRY LIFTS N OF THE FCST AREA.

TEMPS WILL LIKELY GET A BOOST BY THE AFTN HOURS WITH THE
INCREASING BREAKS IN THE PCPN SHIELD...THOUGH OBVIOUSLY
CONSIDERING THE BNDRY LAYER WARMTH COULD GO MUCH HIGHER WITH ANY
BREAKS IN THE CLOUD COVER. HIGHS FROM THE UPR 50S LWR ERN SHORE TO
UPR 60S OVER SOUTH-CENTRAL VA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
NEXT BOUT OF STRONGER/DEEPER DYNAMICAL FORCING AND (THUS) MORE
WIDESPREAD...HEAVIER RAINFALL IS STILL SLATED FOR TONIGHT THROUGH
SAT AM. 00-06Z SHORT RANGE MODELS AND ENSEMBLE MEANS ARE ABOUT AS
ALIGNED AS THEY HAVE EVER BEEN IN TERMS OF HANDLING THIS SYSTEM...
AT LEAST WITH RESPECT TO THE SYNOPTIC FEATURES AFFECTING THE MID
ATLC REGION. SECONDARY WCB DEVELOPMENT COMMENCES TONIGHT AS THE
UPR LOW BEGINS TO PHASE WITH THE SFC LOW OVER THE CAROLINAS. THIS
WILL LEAD TO EVEN MORE FVRBL LEFT-EXIT REGION FORCING VIA THE SRN
JET STREAK (STRENGTHENING DPVA)...WITH ONCE AGAIN DEEPENING
ISENTROPIC ASCENT AS THE ELONGATED E-SE LLVL PULLS IN PLENTY OF
GULF STREAM MOISTURE OFF THE ATLC. PCPN EFFICIENCY WILL BECOME
VERY HIGH FOR THE TIME OF YEAR...WITH THE OPTIMAL LLVL THETA-E
PROFILE HELPING TO BOOST PRECIP WATER VALUES UPWARDS BTWN
1.25-1.5". SPC MAINTAINS A GENERAL OUTLOOK THROUGH SAT ACROSS OUR
REGION...WITH THE FOCUS ON THE LLVL THETA-E RIDGE AXIS ALONG AND
JUST AHEAD OF THE WNW-ESE SURFACE TROUGH. HAVE MAINTAIN TSTM
CHANCES TONIGHT INTO SAT OVER THE SRN HALF OF THE FCST AREA...OR
ESSENTIALLY ALONG AND S OF THE PROJECTED PATH OF THE SFC LOW.

IN TERMS OF QPF...AT THIS POINT GIVEN THE ANTICIPATED STRENGTH AND
DURATION OF THE WAA FORCING AND LOW-MID LVL THRERMODYNAMIC
PROFILE...AMOUNTS COULD EASILY EXCEED 2-3" OVER THE NRN
ZONES...PERHAPS UPWARDS OF 5" FAR NORTH (I.E. LWR MD ERN SHORE)
PER THE LATEST HPC GUIDANCE. AS SUCH...HAVE HOISTED FLOOD WATCHES
OVER AREAS N OF I-64.

AS FOR WINDS...LATEST GUIDANCE CONTINUES TO SUGGEST BEST POTENTIAL
FOR ADVISORY CRITERIA WILL BE ALONG THE LWR ERN SHORE...ESP ALONG
THE MARYLAND BEACHES (I.E. OCEAN CITY) WHERE THE GRADIENT FLOW IS
EXPECTED TO BE STRONGEST. HAVE ALSO HOISTED WIND ADVISORIES ALONG
THE LWR ERN SHORE ZONES ADJACENT TO THE ATLC FOR TONIGHT AND (FOR
OCEAN CITY) SAT AM.

BY SATURDAY NIGHT...THE LOW WILL BE ACROSS CEN VA TO THE LWR
DELMARVA. TO THE SOUTH...THE FLOW WILL BE MORE WESTERLY...FAVORING
LLVL DOWNSLOPE DRYING AND THUS LOWER POPS. ALONG AND N OF THE
LOW...CONTINUED DEEP EASTERLY FETCH (MOISTURE) AND THUS HIGHER
POPS. EVEN S OF THE SFC LOW...WITH THE UPPER LOW ROTATING INTO THE
REGION...WILL CONTINUE TO SEE INSTABILITY SO SHOWERS ARE STILL
POSSIBLE. THE BETTER CHANCE FOR SHOWERS WITH THE UPPER LOW WILL
COME ON SUNDAYS SO HAVE HIGHER POPS ON SUNDAY THAN SATURDAY NIGHT.
BUT THE SHOWER SHOULD BE MORE SCATTERED IN NATURE AND ALSO LIGHTER
WITH THE QPF AMOUNTS.

FOR TEMPERATURES ON FRIDAY AND SATURDAY...CONTINUED LEANING WARMER
AS THE SOUTHERLY FLOW AND MOISTURE SHOULD HELP KEEP TEMPERATURES
ON THE MILD SIDE. BEHIND THE FRONT...CAME DOWN CLOSE TO GUIDANCE
AS THE COLD ADVECTION SHOULD HELP LOWER READINGS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE LATE WEEK/WEEKEND STORM SYSTEM LIFTS TO THE NORTHEAST BY EARLY
NEXT WEEK WITH DECENT MODEL AGREEMENT WITH THE LARGE SCALE FEATURES.
ONE FINAL IMPULSE ROTATES THROUGH THE LOCAL AREA MONDAY BRINGING A
CHANCE OF LIGHT RAIN SHOWERS...PRIMARILY FORM INTERSTATE 95
EASTWARD. DRIER CONDITIONS PREVAIL THEREAFTER WITH THE EASTERN
UNITED STATES REMAINING UNDER A LONGWAVE TROUGH. A WEAK SOUTHERN
STREAM WAVE TRIGGERS A CYCLONE OFF THE SOUTHEAST COAST LATE NEXT
WEEK...BUT AT THIS TIME IT SHOULD REMAIN WELL TO THE SOUTH OF THE
FORECAST AREA. TEMPERATURES WILL AVERAGE NEAR TO SLIGHTLY ABOVE
SEASONAL NORMALS DESPITE THE PRESENCE OF THE UPPER TROUGH...GIVEN A
LACK OF COLD AIR.

&&

.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
ESE FLO AND ON AND OFF PCPN TDY INTO SAT MORNG...WILL RESULT IN
MAINLY IFR AND LIFR CIGS FOR MUCH OF THE TIME ACRS THE AREA. KEPT
CB MENTIONED FOR SE VA/NE NC FOR THIS AFTN. COLD FRONT SWINGS OFF
THE CST SAT AFTN/EVENING...AND CUD SEE MVFR/VFR CONDS DVLP FOR SAT
AFTN INTO EARLY SUN. HOWEVER...LWR CIGS AND VSBYS LIKELY AGAIN SUN
AFTN/EVENG...AS MORE SHRAS AND POSSIBLE TSRAS DEVELOP WITH UPR LVL
LOW MOVING OVERHEAD.

&&

.MARINE...
ADJUSTED HEADLINES FOR ERLY MORNG FCST TO RAMP UP FM SCA TO GALE
WRNG OVR THE CHES BAY...AND THE CSTL WTRS FM FENWICK ISL TO THE NC
VA BORDER. KEEPING SCA ONLY FOR THE CURRITUCK SND...AND THE CSTL
WTRS FM NC VA BORDER TO CURRITUCK BEACH LGT. ESE WNDS WILL INCRS
THIS AFTN AND ESPLY THIS EVENG/TNGT...AS LO PRES MOVES FM THE NC CST
NWRD INTO WCNTRL VA. THESE STRNGER WNDS WILL CONTINUE OVR THE NRN
TWO CSTL ZNS THRU SAT MORNG. WAVES/SEAS WILL QUICKLY INCRS OVR THE
WTRS LATER THIS AFTN THRU TNGT...THEN SEAS WILL REMAIN VRY HIGH OVR
THE NRN CSTL WTRS THRU SAT. WNDS WILL BE CALMER SAT AFTN THRU
SUN...THEN PICK UP A BIT FM THE NNW FOR SUN NGT INTO ERLY TUE.

&&

.TIDES/COASTAL FLOODING...
THE LATEST MDL EXTRATROPICAL WATER LEVEL GUIDANCE IS NOW INDICATING
THE POTENTIAL FOR TIDAL ANOMALIES ON THE ORDER OF 1 TO 1.5 FT ABOVE
MLLW ON SATURDAY. AN EXTENDED PERIOD OF ONSHORE FLOW...WITH STRONG
ESE WIND EXPECTED FRIDAY NIGHT AND SATURDAY MORNING...COULD BRING
ABOUT SOME MINOR TIDAL ISSUES. HOWEVER AT THIS TIME...FORECAST
MAXIMUM HIGH TIDES REMAIN BELOW MAXIMUM ASTRONOMICAL TIDE OR MAT
LEVELS OVER MOST SITES. ONE NOTABLE EXCEPTION IS OCEAN CITY...WHERE
THE LATEST PROJECTED MAX TIDE IS EXPECTED TO PEAK AROUND A HALF FOOT
ABOVE THE MAT...ALTHOUGH STILL AROUND 0.25 FT BELOW MINOR FLOODING
THRESHOLDS. WILL CONTINUE TO MONITOR IN THE COMING DAYS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...FLOOD WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
MDZ021>025.
WIND ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST SATURDAY
FOR MDZ025.
NC...NONE.
VA...FLOOD WATCH FROM THIS EVENING THROUGH SATURDAY MORNING FOR
VAZ049-063-064-072>078-085-099.
WIND ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST SATURDAY FOR
VAZ099-100.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 PM EST THIS
EVENING FOR ANZ630-631-650-652-654.
GALE WARNING FROM 7 PM THIS EVENING TO 4 AM EST SATURDAY FOR
ANZ630>632-654-656.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 7 PM EST THIS EVENING
FOR ANZ632-656.
GALE WARNING FROM 10 PM THIS EVENING TO 10 AM EST SATURDAY FOR
ANZ650-652.
SMALL CRAFT ADVISORY FROM NOON EST TODAY TO 6 AM EDT SUNDAY
FOR ANZ658.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 AM EST SATURDAY FOR
ANZ633.

&&

$$
SYNOPSIS...BKH
NEAR TERM...BKH
SHORT TERM...BKH/ESS
LONG TERM...AJZ
AVIATION...TMG
MARINE...TMG
TIDES/COASTAL FLOODING...AKQ



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