FXUS61 KAKQ 121633 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1133 AM EST FRI MAR 12 2010 .SYNOPSIS... A STRONG AREA OF 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/... FIRST BATCH OF WDSPRD PCPN ASSCTD WITH LAST NITES EVENT NOW MOVG N ACROSS ERN SHORE. IN ITS WAKE...LTST MSAS SHOWING WEAKENING FRNTL BNDRY DRAPED ACROSS FA. DEEP ERLY FLO CONTS WITH TSCTNS LOADED WITH MSTR. FIRST COUPLE OF VSBL PICS SHOWED A FEW BREAKS ACROSS NC/SRN VA CNTYS...BUT THEY HAVE QUICKLY FILLED IN. AIRMASS PROGGED TO REMAIN NRLY SATURATED THIS AFTRN AHEAD OF THE NXT EVENT SLATED FOR TONITE AND SAT. THUS...WILL CONT WITH THE LIKELY TO CATEGORICAL RAIN CHCS THIS AFTRN. TMPS S OF BNDRY IN THE M-U60S...55-60 N OF IT. RAINFALL AMTS LAST NITE AVG BTWN 1/2 TO 1 INCH OVR MOST OF THE FA. 1 TO 1 1/2 INCHES ACROSS NRN MOST CNTYS. GIVEN THIS MUCH RAINFALL LAST NITE PLUS THE FCSTD 1-3 INCHES TONITE...DECIDED TO GO AHEAD AND ADD THE REST OF VA CNTYS TO FFA. SRN TIER CNTYS SHUD SEE AN ADDNTL 1-2 INCHES WHILE 2-4 INCHES FROM CNRTL VA ON N. SOME MINOR FLOODING PSBL JUST ABT ANYWHERE IN THE WATCH AREA AS BANDS OF MDT TO HVY RAINFALL OCCUR TONITE INTO SAT MORN. XPCT AREA RIVERS TO BE A BIT SLOWER TO REACT TO THE RUNOFF. && .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 /16Z 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 6 PM EST 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 6 PM EST THIS EVENING THROUGH SATURDAY MORNING FOR VAZ048-049-060>100. WIND ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST SATURDAY FOR VAZ099-100. MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST SATURDAY FOR ANZ630>632-654-656-658. GALE WARNING FROM 10 PM THIS EVENING TO 10 AM EST SATURDAY FOR ANZ650-652. SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ633. && $$ SYNOPSIS...BKH/MPR NEAR TERM...BKH/MPR SHORT TERM...BKH/ESS LONG TERM...AJZ AVIATION...TMG MARINE...TMG TIDES/COASTAL FLOODING...