000
FXUS61 KLWX 031956
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
256 PM EST WED DEC 3 2008
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE MID-ATLANTIC COAST
TONIGHT. A COLD FRONT WILL PASS THROUGH THE REGION THURSDAY INTO
THURSDAY NIGHT. COLD CANADIAN HIGH PRESSURE WILL BRING CHILLY
CONDITIONS BEHIND THIS FRONT FOR LATE IN THE WEEK. THE NEXT COLD
FRONT WILL PASS THROUGH THE REGION LATER SATURDAY INTO SATURDAY
NIGHT. COLD HIGH PRESSURE BUILD OVERHEAD EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
RDG AXIS ALONG THE CAROLINA/GEORGIA COAST...PLACING CWFA IN SLY
FLOW. DRY AMS AND SUBSIDENCE COMBINING FOR SKC...W/ THE NEAREST
CLDCVR W OF OHVLY. /SIDE NOTE...SNWPACK CLRLY SEEN ON VSBL STLT
ALONG APPLCHNS./ SO...IT/LL TAKE A GOOD PORTION OF THE EVNG BEFORE
CLDS WL SPREAD IN. VLYS SHUD DCPL DURING THAT TIME...SO XPCTG GOOD
EVNG RADL COOLING.
THE GRADIENT WL INCR OVNGT AS CLDS SPREAD IN. THAT SHUD LIMIT ANY
ADDTL COOLING. FOR WRN SXNS...SPCLY THE HIER ELEVS...THINK TEMPS WL
START TO RISE AGN. MSTR APPEARS TO BE MOSTLY MID DECK /OWING TO WAA/
AND HIGH DECK /SHEARING OFF UPR JET/...SO THINK IT/LL STAY DRY TNGT.
DUE TO NON-DIURNAL NATURE OF TEMP CURVE...DIDN/T USE MOS...BUT MIN-T
ENDED UP CLOSE TO BLEND.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
GFS/NAM START DIVERGING IN HNDLG EVOLUTION OF NXT SYS. NRN AND SRN
STREAM S/WVS DO NOT PHASE BUT DO KEEP PACE W/ EACH OTHER. PLUS...UPR
JET SPD MAX WL RESIDE IN ERN GRTLKS TMRW. SO...BEST UPR SUPPORT FOR
PCPN HANGS BHD CDFNT. BUT...NAM SOLN KEEPS CWFA DRY TMRW. WHILE QPF
DOES APPEAR TO BE LMTD...THINK THAT/S GOING A LTL TOO EXTREME.
FROPA 15Z W TO 20-22Z SE. DESPITE LESS THAN STELLAR UPR DYNAMICS...
SFC CNVGNC/BAROCLINICITY/MIDLVL F-VECTOR FORCING SHUD ALL SUPPORT AT
LEAST SOME PCPN. POPS MOSTLY KEPT AT CHC...XCPT WL GO FOR LIKELY IN
THE W.
PLENTY OF COLD AIR BHD FRONT. HWVR...GNRL TIMING HAS SLOWED...AND
TIMING DIFFS ADD AN XTRA LYR OF UNCERTAINTY. IT WUD SEEM THO THAT RA
WL BE THE PREDOMINANT PTYPE BASED ON MEAN TIMING AND LMTD PCPN. IN
THE MTNS...ENUF COLD AIR SHUD SLIDE IN TO CHG PTYPE TO SNW. AS
STATED ABV...WON/T BE MNTNG ACCUMS DUE TO UNCERTAINTY AND SCANT
MSTR.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
A MID-LEVEL TROUGH OF LOW PRESSURE WILL REMAIN OVER THE MID-WEST
INTO SATURDAY NIGHT. A COUPLE OF DISTURBANCES AND THEIR ASSOCIATED
COLD FRONTS WILL ROTATE AROUND THE TROUGH PASSING THROUGH OUR
REGION. THE FIRST ONE IS EXPECTED TO PASS THROUGH THURSDAY NIGHT
AND THE OTHER LATER SATURDAY INTO SATURDAY NIGHT.
THE FIRST COLD FRONT THURSDAY NIGHT WILL PASS THROUGH THE REGION BY
MIDNIGHT. ALTHOUGH THERE IS LITTLE MOISTURE ASSOCIATED WITH THIS
FRONT...WITH A SOUTHWEST FLOW ALOFT THERE SHOULD BE ENOUGH LIFT
BEHIND THE FRONT FOR AT LEAST THE CHANCE OF LIGHT PRECIPITATION.
DESPITE COLDER AIR MOVING IN ALOFT...LOW-LEVEL TEMPERATURES SHOULD
REMAIN JUST WARM ENOUGH FOR MOST LOCATIONS TO SEE RAIN.
HOWEVER...HIGHER ELEVATIONS WILL SEE LIGHT SNOW OR A MIXTURE OF
RAIN/SNOW. ANY SNOWFALL ACCUMULATION SHOULD BE LIGHT AND CONFINED
MAINLY TO THE POTOMAC HIGHLANDS. COLD CANADIAN HIGH PRESSURE WILL
BEGIN TO BUILD INTO THE REGION LATE THURSDAY NIGHT BRINGING DRY AND
CHILLY CONDITIONS.
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH FRIDAY NIGHT BRINGING
DRY AND CHILLY CONDITIONS. A WEAK DISTURBANCE MAY BRING SOME CLOUDS
FRIDAY AFTERNOON INTO FRIDAY NIGHT.
THE NEXT DISTURBANCE AND ITS ASSOCIATED COLD FRONT WILL APPROACH THE
REGION SATURDAY BEFORE PASSING THROUGH SATURDAY NIGHT. THIS SYSTEM
WILL ALSO HAVE LITTLE MOISTURE WITH IT...BUT IT WILL BE A BIT
STRONGER THAN THE FIRST SYSTEM AND IT WILL DIVE A BIT FURTHER SOUTH.
THIS SYSTEM WILL ALSO LEAD TO THE DEVELOPMENT OF LOW PRESSURE OFF
THE MID-ATLANTIC COAST...BUT THIS SHOULD REMAIN FAR ENOUGH TO OUR
EAST NOT TO HAVE ANY IMPACT ON OUR REGION. HOWEVER...THERE SHOULD BE
ENOUGH LIFT AND MOISTURE FOR THE CHANCE OF LIGHT PRECIPITATION
ACROSS THE ENTIRE CWA. GIVEN THE COLDER CONDITIONS MOST AREAS WOULD
GET LIGHT SNOW WITH PERHAPS RAIN ACROSS LOWER SOUTHERN MARYLAND.
LIGHT ACCUMULATIONS ARE POSSIBLE WITH THIS SYSTEM...DETAILS WILL
HAVE TO IRONED OUT AS IT GETS CLOSER.
HIGH PRESSURE WILL APPROACH THE REGION SUNDAY BRINGING DRIER
CONDITIONS...BUT IT WILL TURN OUT BLUSTERY AND COLD. HIGH PRESSURE
WILL BUILD OVERHEAD EARLY NEXT WEEK BEFORE ANOTHER STORM SYSTEM
APPROACHES FROM THE WEST. LATEST GUIDANCE SUGGEST THAT THE PRIMARY
PTYPE WITH THIS SYSTEM WOULD BE RAIN.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
VFR CONDS /CAVU/ TNGT AS HIPRES RDG SLIDES OFF THE COAST. LGT WNDS
AT THE SFC...BUT SWLY FLOW INCRSG ALOFT. HI CLDS INCR OVNGT IN ADVC
OF CDFNT. MID DECK PSBL IN SLY FLOW TMRW. CFP FOR TERMINAL SITES
MID-LT AFTN /ELY AFTN AT MRB/. CIGS WL BE LWRG ALONG/BHD FNT.
ATTM...KEPT IT VFR...THO MRB MAY DROP TO MVFR. PCPN CHCS TOO LMTD TO
REDUCE VSBYS IN TAFS ATTM.
A COLD FRONT WILL BRING LIGHT RAIN TO THE TERMINALS THURSDAY EVENING
ALONG WITH MAINLY MVFR CIGS. VFR CONDITIONS ARE EXPECTED OVERNIGHT
INTO FRIDAY BEHIND THIS FRONT AS HIGH PRESSURE BUILDS ACROSS THE
TERMINALS. ANOTHER WEAK DISTURBANCE MAY BRING MORE CLOUDS FRIDAY
AFTERNOON INTO FRIDAY NIGHT.
A STRONGER DISTURBANCE WILL BRING SUBVFR CIGS AND VSBYS LATE
SATURDAY AND SATURDAY NIGHT ALONG WITH THE CHANCE OF LIGHT SNOW.
HIGH PRESSURE WILL BUILD OVER THE TERMINALS FOR SUNDAY INTO EARLY
NEXT WEEK.
&&
.MARINE...
SLY FLOW INCR ACRS WATERS TNGT. ALTHO WNDS MAY ATTEMPT TO DCPL...
THINK FLOW ALOFT WL BE ABLE TO MIX DWN IN SLY FLOW. HV TWEAKED SCA
A CPL HRS ERLR.
CDFNT APPCHS LT TMRW. MIXING LOOKS LESS FVRBL BTWN SLY PUSH AND POST
FROPA WNDS...SO SCA CONDS APPEAR MORE MARGINAL. WL LEAVE IT UP AS
THOSE CONDS SHUD BE SHORT LIVED.
A COLD FRONT WILL PASS THROUGH THE WATERS THURSDAY NIGHT. SMALL
CRAFT ADVISORY WIND GUSTS UP TO 20 KNOTS ARE LIKELY ACROSS THE
CHESAPEAKE BAY AND LOWER TIDAL POTOMAC THURSDAY NIGHT INTO FRIDAY
MORNING. HIGH PRESSURE WILL BUILD OVER THE WATERS LATER FRIDAY
BRINGING LIGHTER WINDS AND DRY CONDITIONS.
THE NEXT COLD FRONT WILL APPROACH THE WATERS LATE SATURDAY BEFORE
PASSING THROUGH SATURDAY NIGHT. THIS MAY BRING LIGHT SNOW OR RAIN TO
THE WATERS DURING THIS TIME. GUSTY WINDS ARE EXPECTED BEHIND THE
FRONT. A SMALL CRAFT ADVISORY WILL LIKELY BE WARRANTED SUNDAY AND
SUNDAY NIGHT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 10 AM EST
FRIDAY FOR ANZ530>534-537.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EST
THURSDAY FOR ANZ535-536.
&&
$$
SYNOPSIS...BJL
NEAR TERM...HTS
SHORT TERM...HTS
LONG TERM...BJL
AVIATION...HTS/BJL
MARINE...HTS/BJL
