Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250132 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 932 PM EDT THU APR 24 2014 .SYNOPSIS... HIGH PRESSURE OVERHEAD THIS EVENING WILL MOVE OFF THE COAST LATE TONIGHT AND FRIDAY MORNING. A COLD FRONT WILL CROSS THE AREA FRIDAY AFTERNOON AND EVENING. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE AREA SATURDAY AFTERNOON AND EVENING BEFORE THE FRONT STALLS TO OUR SOUTH. SEVERAL WAVES OF LOW PRESSURE WILL DEVELOP ALONG THE STATIONARY BOUNDARY...BRINGING UNSETTLED CONDITIONS TO THE AREA BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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00Z SFC ANALYSIS SHOWS RIDGE AXIS ASSOCIATED WITH AN AREA OF WEAK HIPRES OVER THE COASTAL MID ATLANTIC. CALM WINDS WERE REPORTED BY MAJORITY OF ASOS/AWOS IN THE CWA. HI CLOUDS WILL STREAM IN FROM THE WEST THIS EVE WHICH COULD HINDER RADIATIONAL COOLING A BIT. FCST MIN TEMPS GENERALLY IN THE 40S CWA WIDE THOUGH NRN AND WRN SUBURBS OF DC/BALTIMORE MAY DROP DOWN INTO THE UPPER 30S JUST BEFORE DAYBREAK.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
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A SFC LOW WILL DEEPEN AS IT MOVES INTO THE GREAT LAKES REGION BY FRIDAY MORNING. A SHORTWAVE TROUGH WILL ALSO LIFT NORTHWARD BY FRIDAY MORNING. SOUTHERLY FLOW WILL CONTINUE ACROSS THE MID ATLANTIC AND PWAT VALUES WILL INCREASE TO AROUND AN INCH BY FRIDAY MORNING. SHOWERS WILL MOVE INTO THE CENTRAL FOOTHILLS AND POTOMAC HIGHLANDS AFTER SUNRISE FRIDAY. SHOWERS WILL BECOME WIDESPREAD AND MOVE ACROSS THE MID ATLANTIC REACHING THE BAY BY FRIDAY MIDDAY. FCST SOUNDINGS HAVE LITTLE INSTABILITY BUT SHEAR PROFILES HAVE NEAR 40KTS OF SHEAR BY FRIDAY AFTERNOON EAST OF THE BLUE RIDGE. CLOUDY CONDITIONS ARE EXPECTED FRIDAY BUT ANY BREAKS IN THE CLOUDS WILL INCREASE INSTABILITY WITH THE BEST CHANCE OF TSTMS IN THE PIEDMONT AND SRN MD FRIDAY AFTERNOON AND EVENING. TEMPS WILL RISE INTO THE MID TO UPPER 60S FRIDAY. AREAS IN THE PIEDMONT AND SRN MD HAVE THE POTENTIAL TO GET INTO THE MID 70S IF BREAKS IN THE CLOUDS DEVELOP. THERE IS STILL DECENT MODEL SPREAD REGARDING HOW FAR NORTH CORRIDOR OF MORE UNSTABLE AIRMASS REACHES. 15Z SREF PROBS AND THE 18Z NAM PROVIDE SUPPORT FOR A MORE PRONOUNCED THE WARM/MOIST SECTOR AHEAD OF THE FRONT WITH GREATER THAN 500 J/KG OF SBCAPE DEVELOPING OVER CENTRAL VA AND SRN MD. LLVL SHEAR PROFILES INCREASE DURING THE AFTN WHEN A 50 KT JET MAX AT H8 APPROACHES AHEAD OF A NEGATIVELY TILTED TROUGH. WHILE THE CURRENT SPC D2 OUTLOOK KEEPS SEVERE TSTM RISK JUST SOUTH OF THE AREA...A MORE LIMITED/CONDITIONAL THREAT DOES EXIST FOR THE SEVERE THREAT TO EXPAND FURTHER NORTH INTO THE EXTREME SRN TIER OF THE CWA.
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&& .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... PCPN SHOULD BE ON THE WANE AS THE SHORT WV MOVES OFF THE CST - RW XPCTD IN THE ERN PART OF THE FCST THRU MDNGT FRI NGT. LOWS 45-50. SKIES SHOULD BE CLRG SAT MRNG. MID ATLC WL BE IN UPR LVL CYCLONIC FLOW. AT THIS TIME OF YR SUCH AS SET UP COULD CREATE A PD OF MIDDAY CLDNS/AFTN RW...BUT FOR NOW WL LV THAT OUT AS THE CHC WOULD MOST LKLY ONLY EXIST. HIGHS SHOULD BE IN THE L70S. HIGH PRES RDG WL RMN OVR THE E CST SAT NGT AND SUN. THE COMBO OF THE HIGH AND LOW PRES E OF CAPE COD WL LEAD TO A NRLY FLOW WHICH WL KEEP TEMPS IN THE 65-70 RANGE SUNDAY. GFS HAS 500 MB RIDGE AXIS BLDG OVR AREA ERY NEXT WEEK BEFORE MVG OFSHR TUESDAY NIGHT. MANY CHCS OF WETNESS DURG THE MIDWEEK TIMEFRAME - AREAS OF SUPPORTING VORT ENTERING RGN TUESDAY AFTN...WEDNESDAY MRNG THROUGH THURSDAY MRNG AND AGAIN FRIDAY MRNG. SEEMS HPC ENSEMBLE IS MVS SYS E ARND 12 HRS FASTER THAN GFS/ECMWF. CLOSED 500 MB LOW WL REMAIN CENTERED OVR NRN PLAINS/GT LAKES AREA THROUGH THE PD. EURO IS IMPLYING A CAD WEDGE WL DVLP WED. THIS WOULD HELP IN KEEPING TEMPS BLO NRML...PSBLY HIGHS ONLY IN THE 50S! && .AVIATION /01Z FRIDAY THROUGH TUESDAY/...
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HIPRES OVERHEAD RESULTING IN LGT WINDS AND VFR CONDITIONS TNGT. SLY WINDS WILL INCREASE ON FRI AHEAD OF A COLD FRONT. THE FRONT MOVES THRU FRI AFTN AND EVE. SHRA WILL SHOULD REACH MRB/CHO BY MIDDAY AND ERN TERMINALS DURING THE AFTN. COVERAGE OF SHRA EXPECTED TO BE WIDESPREAD INTO FRI EVE. ISO TSTMS DURING THE AFTN/ERY EVE POSSIBLE...PARTICULARLY IN VC OF CHO. SOME SHOWERS MAY BE HEAVY AND REDUCE VSBYS/CIGS BUT THERE IS STILL SOME UNCERTAINTY IN THE TIMING AND EXTEND OF FLGT RESTRICTIONS. RW SHOULD BE EXITING THE RGN FRI NGT...THEN VFR CONDS SAT MRNG. THE PSBLTY OF SCT AFTN RW EXISTS SAT...THEN VFR AGN SAT NGT AND SUN. THE PTNL EXISTS FOR LOW CIGS/R DURG THE FIRST HALF OF NEXT WK.
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&& .MARINE...
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LGT WINDS TNGT WITH HIPRES OVER THE WATERS. HIGH PRESSURE MOVES OFFSHORE TOWARD FRI MRNG WITH SLY RETURN FLOW INCREASING ACROSS THE WATERS FRIDAY. A SCA IS IN EFFECT FRIDAY AFTERNOON. SHOWERS WILL BECOME WIDESPREAD FRIDAY AFTERNOON AND EVENING. A FEW SHOWERS MAY BECOME HEAVY WITH REDUCED VSBYS AND WATERSPOUTS WILL BE POSSIBLE TOWARDS FRIDAY EVENING. SCA IN EFFECT FOR THE WATERS FRI NGT. GALES POSSIBLE BEHIND THE COLD FRONT LATE FRI NGT INTO SAT MRNG. SCA LIKELY THIS WEEKEND WITH GALES POSSIBLE BEHIND ANOTHER COLD FROPA SAT EVE.
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&& .TIDES/COASTAL FLOODING...
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NWLY FLOW OVER THE PAST FEW DAYS HAS RESULTED IN TIDAL ANOMALIES THAT ARE CURRENTLY AROUND ONE-HALF FOOT BELOW NORMAL THIS EVE. SOUTHERLY FLOW WILL STRENGTHEN AHEAD OF A COLD FRONT FRIDAY AFTERNOON THROUGH FRIDAY EVENING. THIS WILL CAUSE TIDAL ANOMALIES TO SHARPLY INCREASE. THE FLOW WILL TURN OFFSHORE BEHIND A COLD FRONT AFTER MIDNIGHT...CAUSING TIDAL ANOMALIES TO DECREASE BY SATURDAY MORNING. MINOR COASTAL FLOODING IS POSSIBLE NEAR TIMES OF HIGH TIDE FRIDAY NIGHT AT SENSITIVE LOCATIONS. LATEST CBOFS GUIDANCE FORECASTS ANNAPOLIS TO REACH MINOR COASTAL FLOODING FRIDAY NIGHT.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON FRIDAY TO 6 AM EDT SATURDAY FOR ANZ531>534-537-539>543. SMALL CRAFT ADVISORY FROM NOON TO 6 PM EDT FRIDAY FOR ANZ530- 535-536-538. SMALL CRAFT ADVISORY FROM MIDNIGHT FRIDAY NIGHT TO 6 AM EDT SATURDAY FOR ANZ530-535-536-538.
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&& $$ SYNOPSIS...JRK NEAR TERM...JRK SHORT TERM...JRK/HAS LONG TERM...CEM/WOODY! AVIATION...JRK/WOODY! MARINE...JRK/WOODY! TIDES/COASTAL FLOODING...JRK

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