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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KAKQ 291210
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
710 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 /12Z THURSDAY THROUGH MONDAY/...
MAINLY CLEAR SKIES (SOME HIGH CIRRUS) WITH HIGH PRESSURE OVER THE REGION
AS OF 12Z. 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 18Z 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. CIGS WILL AVG 5-10 K FT. A
GUSTY NW WIND IS EXPECTED FRIDAY WITH GUSTS TO 30 KT (MAYBE AS
HIGH AS 35 KT AT KSBY) 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 10 AM FOR NC COASTAL WATERS...OTHERWISE ALL
HEADLINES HAVE ENDED IN THE NEAR TERM.

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 10 AM EST THIS MORNING FOR ANZ658.

&&

$$
SYNOPSIS...BMD
NEAR TERM...BMD
SHORT TERM...BMD
LONG TERM...MPR
AVIATION...LKB/DAP
MARINE...LKB/MPR