Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 290932 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 432 AM EST THU JAN 29 2015 .SYNOPSIS... HIGH PRESSURE WILL SLIDE TO THE SOUTHEAST TODAY. A COLD FRONT CROSSES THE REGION LATE TONIGHT. COLD HIGH PRESSURE THEN RETURNS TO THE MID ATLANTIC REGION LATE FRIDAY THROUGH SATURDAY NIGHT. A LOW PRESSURE SYSTEM MOVING OUT OF THE GULF COAST STATES WILL AFFECT THE AREA SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... HIGH PRESSURE OVER THE AREA THIS MORNING WILL SLIDE SSE THROUGH THE DAY AS ANOTHER CLIPPER SYSTEM CROSSES THE GREAT LAKES AND APPROACHES THE NORTHEAST U.S. TODAY. BREEZY SOUTH WINDS WILL DEVELOP FROM WEST TO EAST THIS AFTN AS THE SFC PRESSURE GRADIENT TIGHTENS UP BTWN THE HIGH SHIFTING SSE AND THE APPROACHING CLIPPER SYSTEM. THE MIXING SHOULD HELP TEMPERATURES WARM TO NEAR NORMAL VALUES WEST...WITH HIGH TEMPS SLIGHTLY BELOW NORMAL EAST. OVERALL HIGHS WILL BE IN THE MID TO UPPER 40S (LOW-MID 40S NRN NECK AND MD/VA EASTERN SHORE). HIGH CLOUDS BTWN 15-20KFT WILL ALSO INCREASE FROM WEST TO EAST THROUGH THE DAY AND MAY HAMPER TEMPS FROM WARMING ANOTHER DEGREE OR TWO BUT EXPECT MIXING TO OVERCOME THIS... ESPECIALLY ACROSS THE WRN HALF OF THE CWA. A WARM FRONT LIFTING THROUGH THE AREA LATE THIS AFTN/EARLY EVENING WILL PROVIDE A FOCUS FOR PRECIPITATION AHEAD OF THE COLD FRONT ASSOCIATED WITH THE CLIPPER SYSTEM. AT THE ONSET...PRECIP IS EXPECTED TO DEVELOP LATE AFTN/EARLY EVENING NORTH OF RICHMOND FROM ROUGHLY LOUISA TO SALISBURY AND THEN SHIFT OVER THE MD LOWER EASTERN SHORE THIS EVENING BEFORE LIFTING WELL NORTH OF THE AREA. WET BULB ZERO HEIGHTS BEGIN AROUND 6KFT AND TEMPERATURES WILL BE WARM ENOUGH TO SUPPORT MAINLY RAIN. THERE IS A BRIEF PERIOD OF LIFT THROUGH THE BOTTOM PORTIONS OF THE DENDRITIC GROWTH ZONE (00-03Z)...THEREFORE THERE IS A SLIGHT CHANCE OF SLEET BRIEFLY MIXING WITH RAIN OVER THE NRN NECK/MD EASTERN SHORE AFTER DARK. PRECIP WILL COME TO AN END LATE IN THE EVENING AS BEST MOISTURE/ENERGY LIFTS NORTH OF THE MID ATLANTIC REGION. MOISTURE CONTINUES TO BE VERY LIMITED WITH QPF AMTS NO HIGHER THAN 0.03 INCHES AT BEST. THE COLD FRONTAL PASSAGE IS CENTERED AROUND 06Z (1 AM) AND IS EXPECTED TO BE OFFSHORE BY DAYBREAK. COLD AIR ADVECTION AND DRYING ALOFT WILL COMMENCE AFTER MIDNIGHT AND UNSTABLE LOW-LEVEL LAPSE RATES WILL ALLOW WLY WINDS TO REMAIN BREEZY OVERNIGHT. EXPECT LOWS IN THE LOWER 30S NW TO UPPER 30S FAR SE. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... FRIDAY WILL BE A COLD BRISK DAY UNDER MOSTLY SUNNY SKIES AS A CANADIAN HIGH PRESSURE BUILDS OVER THE OHIO VALLEY...RESULTING IN A VERY TIGHT SFC PRESSURE GRADIENT. GUSTY NW WINDS OF 30-35 MPH WILL DEVELOP BY MID MORNING AND PERSIST INTO FRI EVENING BEFORE DIMINISHING OVER INLAND AREAS. CLOSER TO THE COAST...WINDS MAY GUST UP TO 40 MPH AT TIMES DURING THE DAY AND THEN REMAIN GUSTY TO AROUND 30 MPH FRI NIGHT. COLD AIR ADVECTION WILL BE IN FULL FORCE FRI INTO FRI NIGHT AS AN UPPER TROUGH SWINGS ACROSS THE MID ATLANTIC REGION. HIGH TEMPERATURES WILL RUN ABOUT 5-7 DEGREES BELOW NORMAL DESPITE THE WELL-MIXED ENVIRONMENT. EXPECT HIGHS IN THE LOW-MID 40S (UPPER 30S NRN NECK AND MD/VA EASTERN SHORE). LOW FRI NIGHT IN THE UPPER TEENS NORTH AND WEST OF RICHMOND... LOWER 20S ELSEWHERE...UNDER MOSTLY CLEAR SKIES. THE COMBINATION OF WIND AND COLD TEMPS WILL KEEP WIND CHILL VALUES IN THE UPPER 20S TO MID 30S DURING THE DAY FRI...AND FROM 5-15 DEGREES FRI NIGHT. THE CANADIAN HIGH PRESSURE SETTLES OVER THE MID ATLANTIC REGION SAT/SAT NIGHT WITH A CONTINUATION OF COLD AND DRY CONDITIONS. HIGHS IN THE LOWER 40S MOST AREAS...UPPER 30S ALONG THE COAST FROM THE NRN NECK TO VIRGINIA BEACH...AND IN THE LOW-MID 30S MD/VA EASTERN SHORE. NW WINDS REMAIN BREEZY ALONG THE COAST ON SAT WITH GUSTS OF 25-30 MPH AND WIND CHILLS RANGING FROM THE MID-UPPER 30S SW TO LOW-MID 20S NE. LOWS SAT NIGHT IN THE 20S WITH INCREASING CLOUDS FROM SW TO NE OVERNIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... TIMING DIFFERENCES ALONG WITH SOME SIGNIFICANT 12Z MODEL CHANGES MAKES THIS A LOW CONFIDENCE FORECAST SUN INTO MON. GFS MUCH FASTER IN BRINGING PCPN ACROSS THE MID ATLNTC RGN SUNDAY THAN BOTH THE ECMWF AND CANADIAN. THE QUICKER GFS SOLN WOULD LEAD TO P-TYPE ISSUES ACROSS NRN MOST CNTYS SUNDAY WHILE THE SLOWER SOLNS WUD MAINLY BE RAIN (OR A RAIN WET SNOW MIX ACROSS THE NORTH) IN THE AFTN. CONVERSELY...THE GFS IS QUICKER TO END PCPN LATE SUNDAY NIGHT WHILE THE SLOWER SOLNS KEEP PCPN GOING FOR THE BETTER PART OF MON WITH COLDER AIR OOZING SOUTH. WITH THE ABOVE IN MIND...TRIED TO BLEND THE FORECAST AS MUCH AS PSBL KNOWING THAT LATER MODEL RUNS SHOULD SHED BETTER LIGHT ON THE SYSTM. DRY AND COLD SAT NIGHT WITH INCRG CLDNS. LOWS IN THE 20S XCPT L30S SERN CSTL AREAS. KEPT A BIT OF FCST CONTINUITY AND BROUGHT LOW CHC POPS ACROSS WRN CNTYS SUNDAY MORNING. THICKNESSES SUGGEST SOME SLEET PSBL AT THE START ACROSS NWRN MOST CNTYS WITH RAIN OVRSPRDG THE FA SUNDAY AFTN AS THE LOW PRS TRACKS ACROSS NRN VA. HIGHS IN THE 40S AS THE COLD AIR LURKS JUST NORTH OF THE FA. LIKELY RAIN SUNDAY EVENING ACROSS THE FA...BUT LWRD TO CHC POPS AFTR MIDNIGHT. KEPT A RAIN/SNOW MIX ACROSS NRN MOST CNTYS LATE AS THE PCPN ENDS. ANY P TYPE ISSUES WILL ALL DEPEND ON HOW FAST THE COLDER AIR TO THE NORTH CAN COME SOUTH BEFORE PCPN ENDS. LOWS SUNDAY NIGHT IN THE 30S TO NR 40 ACROSS NC NE CNTYS NR THE ALBEMARLE SND. SPLIT MONDAYS FCST UP INTO 2 SEGMENTS AS WELL. CHC RAIN ALONG AND EAST OF I-95 IN THE MORNING...DRYING IT OUT IN THE AFTN AS THE TRAILING FRNT CLRS THE COAST. COULD EVEN SEE A RAIN/SNOW MIX ACROSS THE LWR MD ERN SHORE ERLY MONDAY. HIGHS IN THE U30S N TO M-U40S S. CANADIAN HIGH PRS BUILDS INTO THE AREA MON NIGHT THRU TUES NIGHT. LOWS MON NITE UTEENS TO U20S. HIGHS TUE IN THE 30S. LOWS TUE NIGHT IN THE 20S TO NR 30. YET ANTHR MOIST SRN STREAM SYSTM PROGGED TO COME OUT OF THE GULF COAST STATES AND MOVE NE ALONG THE SERN COAST WED. THIS SYSTM BEARS WATCHING AS THE COLD AIR MAY BE HARDER TO DISLODGE. WENT WITH CHC POPS (LIQUID) FOR NOW WITH HIGHS 40-45. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... CLEAR SKIES WITH HIGH PRESSURE OVER THE REGION AS OF 06Z. HIGH PRESSURE MOVES OFFSHORE LATER TODAY AS A COLD FRONT APPROACHES FROM THE NW. THE WIND WILL BECOME SOUTHERLY ALONG WITH AN INCREASE IN MID/HIGH CLOUDS...SKIES GENLY BECOMING BKN/OVC BY 15Z BUT CIGS REMAIN 10-15K FT. THE COLD FRONT WILL CROSS THE AREA LATE TONIGHT WITH ONLY A SLIGHT CHC OF -SHRA ALONG AND N OF A RIC-SBY LINE...AND PERHAPS PCPN ENDING AS A MIX OF -RASN AT SBY. A GUSTY NW WIND IS EXPECTED FRIDAY AS CANADIAN HIGH PRESSURE BUILDS IN FROM THE NW. THAT AREA OF HIGH PRESSURE SLIDES ACROSS THE REGION FRIDAY NIGHT AND SATURDAY...WITH A MORE MOIST FRONTAL SYSTEM IMPACTING THE REGION SUNDAY INTO MONDAY. && .MARINE... EXTENDED SCA`S THROUGH 7 AM FOR NC COASTAL WATERS...OTHERWISE ALL HEADLINES HAVE ENDED. ONLY A BRIEF PERIOD OF "SUB SCA" CONDITIONS TODAY BEFORE THE NEXT SYSTEM APPROACHES FROM THE WEST. N WINDS BECOME RATHER LIGHT BY MID-LATE MORNING...THEN SHIFT TO THE SSE THIS AFTN AND EVENTUALLY THE SSW TONIGHT. HAVE RAISED SCA HEADLINES OVER NORTHERN PORTIONS OF THE MARINE AREA LATER THIS EVENING AS SSW WINDS INCREASE AHEAD OF THE COLD FRONT. STILL...THE MORE SIGNIFICANT EVENT COMES FRI/FRI NIGHT IN THE WAKE OF THE COLD FRONT AS VERY COLD AIRMASS WILL BRING OPTIMAL MIXING IN WHAT WILL ALREADY BE A STRONG GRADIENT WIND. HAVE RAISED GALE WARNINGS FOR MOST OF THE REGION...WITH STRONG SCA`S EXPECTED FOR THE UPPER JAMES AND CURRITUCK SOUND. WINDS ARE EXPECTED TO GUST TO 35-40 KT ACRS THE SOUTHERN COASTAL WATERS AND THE BAY...WITH 40-45 KT OVER COASTAL WATERS NORTH OF PARRAMORE ISLAND. RAPPAHANNOCK/YORK AND LOWER JAMES WILL BE MORE MARGINAL FOR GALES BUT DECIDED TO GO FOR IT DUE TO THE OPTIMAL MIXING SCENARIO AND 900 MB WINDS PROGGED TO BE CLOSE TO 40 KT. GIVEN TMPS FALLING BLO 30 DEGREES...FREEZING SPRAY REMAINS IN FORECAST WITH THE POTENTIAL FOR A FREEZING SPRAY ADVSRY ACROSS NRN CSTL WTRS WHERE AIR TMPS IN THE L20S ARE XPCTD. SEAS/WAVES QUICKLY INCREASE IN RESPONSE TO THE GUSTY WINDS. SEAS AVG 7-10 FT WITH BAY WAVES 4-6 FT DURING THIS PERIOD. CNDTNS BEGIN TO IMPROVE SAT AFTN/NIGHT AS THE CANADIAN HIGH TRACKS OVR THE RGN. NXT SYSTEM IS ANTICIPATED TO TRACK INTO THE AREA FROM THE SOUTHWEST LATE SUN INTO MON. WILL LIKELY SEE ANTHR ROUND OF SCA`S WITH THIS SYSTM. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...GALE WARNING FROM 10 AM FRIDAY TO MIDNIGHT EST FRIDAY NIGHT FOR ANZ630>632-634>636-638. SMALL CRAFT ADVISORY FROM 10 AM FRIDAY TO 6 AM EST SATURDAY FOR ANZ633-637. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST FRIDAY FOR ANZ630-631-650-652. GALE WARNING FROM 10 AM FRIDAY TO 6 AM EST SATURDAY FOR ANZ650- 652-654. GALE WARNING FROM 1 PM FRIDAY TO MIDNIGHT EST FRIDAY NIGHT FOR ANZ656-658. SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ658. && $$ SYNOPSIS...BMD NEAR TERM...BMD SHORT TERM...BMD LONG TERM...MPR AVIATION...LKB/DAP MARINE...LKB

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