Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 211038 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 638 AM EDT TUE APR 21 2015 .SYNOPSIS... HIGH PRESSURE BUILDS IN FROM THE SOUTHWEST TODAY AND MOVES OFFSHORE TONIGHT. A COLD FRONT APPROACHES FROM THE NORTHWEST WEDNESDAY MORNING AND CROSSES THE MID ATLANTIC LATER WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. HIGH PRESSURE RETURNS THURSDAY AND FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE CURRENT SURFACE ANALYSIS DEPICTS A COLD FRONT CROSSING THE MID ATLANTIC REGION...WITH WEAK HIGH PRESSURE OVER THE LOWER MISSISSIPPI VALLEY. ALOFT...A POTENT SHORTWAVE TROUGH IS PUSHING THROUGH THE NRN MID ATLANTIC ASSOCIATED WITH A BROADER TROUGH OVER THE GREAT LAKES. SCT SHOWERS/TSTMS LINGER AHEAD OF THE COLD FRONT OVER NE NC AND FAR SE VA EARLY THIS MORNING...BUT HAVE DEMONSTRATED A WEAKENING TREND OVER THE PAST 1-2HRS. 20-30% POPS WILL CONTINUE ACROSS THESE PORTIONS THROUGH 6 AM...WITH A DRY FORECAST THEREAFTER. THE UPPER TROUGH WILL CONTINUE TO DIG OVER THE REGION TODAY...WITH THE COLD FRONT PUSHING OFFSHORE EARLY THIS MORNING. SURFACE HIGH PRESSURE WILL BUILD ACROSS THE SOUTHEAST STATES WITH A MOSTLY SUNNY SKY DEVELOPING ACROSS THE AREA. DEEP MIXING AND DOWNSLOPE FLOW WILL ALLOW HIGHS TO REACH 70-75...AND MILD TEMPERATURES SHOULD EVEN REACH THE ATLANTIC COAST WITH A WESTERLY WIND THROUGH AT LEAST MID-AFTERNOON (SEA BREEZES MAY PREVAIL BY LATER AFTERNOON). DEWPOINTS ARE EXPECTED TO DROP INTO THE LOW/MID 30S OVER INTERIOR PORTIONS BY AFTERNOON. THIS WILL RESULT IN MIN RH VALUES OF 20-30% (30-40% CLOSER TO THE COAST). NO FIRE WEATHER CONCERNS THOUGH DUE TO SUBSTANTIAL RAIN SUNDAY NIGHT/EARLY MONDAY. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... A STACKED UPPER LOW WILL REMAIN ANCHORED OVER THE GREAT LAKES REGION AND SRN CANADA THROUGH THURSDAY DUE TO A BLOCKY FLOW PATTERN OVER THE HIGH LATITUDES. A SERIES OF UPPER LEVEL IMPULSES WILL ROUND THE BASE OF THE UPPER LOW...WITH THE FIRST ROUNDING THE BASE OF THE TROUGH TUESDAY NIGHT AND WEDNESDAY. THIS WILL ALLOW SURFACE HIGH PRESSURE TO MOVE OFFSHORE WITH A FAST MOVING COLD FRONT RACING ACROSS THE MID ATLANTIC LATER WEDNESDAY AFTERNOON AND EVENING. DEEP LAYER SOUTHWEST FLOW...DEEP MIXING...AND A DRY LOW-LEVEL AIRMASS WILL MAKE IT DIFFICULT TO GENERATE SHOWERS/TSTMS AHEAD THE OF THE COLD FRONT WEDNESDAY AFTERNOON. THE SYSTEM IS RATHER DYNAMIC...SO 30-40% POPS WILL BE MAINTAINED ACROSS NRN PORTIONS AND 20-30% ACROSS CENTRAL PORTIONS (SUB 15% FAR S/SE) DESPITE UNFAVORABLE THERMODYNAMIC CONDITIONS. HIGHS WEDNESDAY SHOULD AVERAGE IN THE LOW/MID 70S AFTER MORNING LOWS IN THE MID/UPPER 40S. DRY AND BREEZY WEDNESDAY...BUT AGAIN RECENT RAIN AND THE POTENTIAL FOR LATER AFTERNOON SHOWERS/TSTMS SHOULD LIMIT FIRE WEATHER CONCERNS. 00Z NUMERICAL GUIDANCE SUPPRESSES ANY ADDITIONAL SHOWERS WELL S OF THE REGION LATER WEDNESDAY NIGHT INTO THURSDAY AS THE BOUNDARY PUSHES INTO NRN GA AND SC. COOLER HIGH PRESSURE BUILDS INTO THE MID ATLANTIC BY THURSDAY. FORECAST HIGHS THURSDAY RANGE FROM THE LOW/MID 60S N...TO NEAR 70 SE. MORNING LOWS SHOULD RANGE FROM AROUND 40 NW...TO AROUND 50 SE. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... COLD FRONT MOVES SOUTH OF THE AREA THURS NIGHT FOLLOWED BY COOL HIGH PRESSURE BUILDING IN FROM THE NW. DRY WITH LOWS BOTH THURS AND FRI NIGHTS 40-50 XCPT A FEW U30S NWRN MOST CNTYS. HIGHS FRI M-U60S. NXT SYSTM PROGGED TO TRACK ACROSS THE CAROLINAS SAT. ECMWF SOMEWHAT FRTHR SOUTH WITH ITS MOISTURE FIELDS THAN GFS. BEST SPRT FOR PCPN WILL BE ACROSS SRN HALF OF FA WHERE CHC POPS WILL BE MAINTAINED. SLGHT CHC ACROSS THE NRTH. COOL SAT WITH HIGHS 60-65. PCPN ENDS SAT EVE AS SYSTM EXITS OFF THE COAST. LOWS IN THE 40S. CANADIAN HIGH PRESSURE DOMINATES ERLY NEXT WEEK WITH ANY PCPN STAYING SOUTH OF FA. DRY WITH A SLOW MODERATING TREND. HIGHS SUN IN THE L-M60S. LOWS SUN NIGHT IN THE 40S. HIGHS MON M-U60S. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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VFR THRU THE 12Z TAF PERIOD. A COLD FRNT IS PUSHING OFFSHORE THIS MORNG...WITH ANY CHC OF PCPN OVER AT ALL TAF SITES. W/NW WINDS WILL REMAIN GUSTY THIS MORNG AND AFTN BEHIND THE FRNT...UP TO 20-25 KT AT TIMES. OTWS...JUST SOME MID-LEVEL CLOUDS EXPECTED TDA AS WEAK SFC HI PRES BLDS OVER THE SE STATES. WINDS DIMINISH AND BCM SWLY TNGT. OUTLOOK...THE SURFACE HIGH MOVES OFFSHORE WEDNESDAY. A COLD FRONT CROSSES THE AREA WEDNESDAY NIGHT WITH A CHC OF SHOWERS MAINLY AT RIC AND SBY. HIGH PRESSURE AND DRY WEATHER RETURN THROUGH FRIDAY.
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&& .MARINE... THE SCA OVER THE BAY/LWR JAMES HAS BEEN ALLOWED TO EXPIRE AS A COLD FRNT SLIDES THRU THE AREA WITH LIGHTER WINDS POST-FRNTAL DUE TO WEAK CAA. COULD SEE AN HR OR TWO OF GUSTS UP TO 20 KT BUT NOT EXPECTED TO LAST LONG ENUF OR WIDESPREAD ENUF TO WARRANT A SCA EXTENSION. OTWS...5-7 FT SEAS CONTINUE OVER THE CSTL WTRS...WHICH WILL SUBSIDE TO BLO 5 FT FM S TO N THRU THE DAY TDA AS THE COLD FRNT PUSHES OFFSHORE AND WINDS BCM WLY. WEAK HI PRES THEN BLDS IN FOR THIS AFTN. ANOTHER COLD FRNT CROSSES THE WTRS WED AFTN/EVENG...WITH PRE-FRNTAL WINDS/WAVES/SEAS CLOSE TO SCA THRESHOLDS. WITH THE CURRENT HEADLINES OUT AND LO CONFIDENCE WITH REACHING CRITERIA WED...WILL HOLD OFF ON ANY HEADLINES FOR THIS ATTM. WEAK CAA BEHIND THIS FRNT AS WELL. NW FLOW SETS UP BEHIND THE COLD FRNT WITH SUB-SCA CONDS EXPECTED AS SFC HI PRES BLDS IN FM THE W THU AND FRI. && .HYDROLOGY... RIVER RISES DUE TO RECENT RAIN ARE EXPECTED FOR THE JAMES RIVER...WITH THE RICHMOND WESTHAM GAUGE APPROACHING MINOR FLOODING TONIGHT AND WEDNESDAY. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR ANZ650. SMALL CRAFT ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR ANZ652.
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&& $$ SYNOPSIS...AJZ NEAR TERM...AJZ SHORT TERM...AJZ/SAM LONG TERM...MPR AVIATION...MAS MARINE...MAS HYDROLOGY...

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