FXUS61 KLWX 030513
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1213 AM EST THU DEC 3 2009
.SYNOPSIS...
LOW PRESSURE OVER WEST TENNESSEE WILL TRACK INTO THE OHIO VALLEY
THIS EVENING AND INTO UPSTATE NEW YORK THURSDAY MORNING. HIGH PRESSURE
BUILDS IN THURSDAY NIGHT AND FRIDAY. A COASTAL DISTURBANCE
DEVELOPS OFF THE CAROLINAS SATURDAY. HIGH PRESSURE WILL RETURN FOR
SUNDAY AND MONDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ANOTHER UPDATE THE TO FORECAST...MAINLY TO ADD IN SOME THUNDER TO
THE FAR WESTERN ZONES AND RAISE POPS TO CATEGORICAL. A LINE OF
SHOWERS HAS BEGUN TO ORGANIZE OVER WEST VIRGINIA. OVER THE LAST
FEW HOURS...A FEW POSITIVE LIGHTNING STRIKES HAVE BEEN NOTED.
ALSO...THESE SHOWERS AND ISOLATED THUNDERSTORMS...WILL HAVE TO THE
POTENTIAL TO PRODUCE GUSTY WINDS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
PCPN SHOULD SHUT DOWN QUICKLY LATE TNGT W/ THE XCPTN OF IN FAVORED
UPSLOPE IN THE FAR W...HOWEVER TEMPS WARM ENOUGH THAT PCPN WOULD
RMN IN LIQUID FORM. MAJORITY OF CWA WL XPRNC CLRG DURG THE AFTN
HRS. IT WL BE BRZY ON NWRLY WINDS...BUT NOT CONTEMPLATING ANY SPL
WIND PRODUCT.
TEMP WL RANGE FM M40S HIGHLANDS TO A60 ALONG THE BAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
THE LOW PRESSURE SYSTEM CURRENTLY AFFECTING THE AREA WILL QUICKLY
ACCELERATE TO THE NE AND INTO OVER NOVA SCOTIA BY LATE THU. THE
RESIDUAL PRECIP WILL BE SLIDING AROUND THE BACKSIDE OFT THE SYSTEM
AND PUSHING INTO THE WINDWARD SIDE OF CNTRL APLCNS INTO EARLY FRI.
VERY LIGHT QPF OVERALL FROM THIS UPSLOPE MOISTURE...AND MAINLY A
RAIN-SNOW MIX FROM LATE THU INTO THE OVERNIGHT HRS...CHANGING OVER
TO ALL SNOW INTO THE PRE-DAWN HRS AND DISSIPATING BY LATE MRNG FRI.
E OF THE APLCNS...DRYING OUT FOR THE REST OF THE WORK WEEK /FROM THU
AFTN INTO LATE FRI/.
THIS ACTIVE PATTERN WON/T JUST LEAVE W/OUT ANOTHER ROUND...WHICH IS
CURRENTLY DIVING DOWN THE FRONT RANGE OF THE ROCKIES. THIS SMALL BUT
POTENT UPPER WAVE WILL SINK INTO THE TX GULF COAST LATE FRI. THIS IS
A GOOD PLACE FOR IT TO TAP INTO SUBSTANTIAL MOISTURE /WHICH IS
LIKELY TO OCCUR/ AS IT BEGINS TO PHASE W/ YET ANOTHER UPPER EMBEDDED
VORT MAX STREWN ACROSS THE OHIO RVR VLY...DOWN ACROSS THE LOWER
MISSISSIPPI VLY. THE RESULTANT SYSTEM WON/T BE A CLASSIC COASTAL LOW
SINCE SEVERAL SMALLER WAVES OF LOW PRESSURE ALONG THE IMMEDIATE
GULF COAST AND SRN ATLC COAST WILL TAKE-AWAY FROM ENERGY OF THE LOW
OVER THE TX/LA COAST. BUT EVEN AS THE MAIN LOW AND MUCH OF THE
FORCING MAKES A DIRECT NE TREK AWAY FROM THE MID ATLC COAST THIS
WEEKEND.
THE WEAKENING AND DISSIPATING UPPER WAVE BEHIND THE SFC FORCING WILL
STILL BE BACK OVER THE INLAND SOUTHEASTERN STATES. EVEN AS THE WAVE
LOSES ITS POTENCY AS IT PULLS UP OVER THE SRN APLCNS...IT LOOKS TO
BE ENOUGH FOR REGIONAL BATCH OF PRECIP TO GLIDE UP THE APLCN CHAIN
AND THE ERN SEABOARD TO PUSH INTO THE SRN-MOST ZONES INTO EARLY SAT.
LOW LEVEL THICKNESSES MAY BE ENOUGH TO SUPPORT A CHANGEOVER TO SNOW
AND/OR A MIX OF RAIN/SNOW OVER THE MID ATLC /ESPECIALLY THE
CNTRL-SRN SHENANDOAH VLY AND INTO THE PIEDMONT/. AS THE UPPER TROF
AXIS WILL PUSH ACROSS THE CWA DURING THE AFTN/EVENING HRS ON
SAT...TAKING THE PRECIP OFF THE COAST AHEAD OF IT W/ THE QUICK
DISSIPATION INTO THE LATE NIGHT HRS.
A COUPLE OF WEAK EMBEDDED UPPER WAVES WILL PUSH THRU THE CNTRL
PLAINS EARLY NEXT WEEK BUT FALL SHORT OF IMPACTING AREAS E OF THE
APLCNS UNTIL THE MID-WEEK SYSTEM WHICH DEVELOPS A BIT FURTHER S AND
THEN SLIDES ACROSS THE EAST COAST WED/THU.
&&
.AVIATION /05Z THURSDAY THROUGH MONDAY/...
LIGHT RAIN CONTS THIS EVE AMID WARM ADVCTN PATTERN. LLVL JET NOTED
ON VWP PRODUCT LKLY PRODUCING A GREAT DEAL OF TURBULENCE NEAR MOST
TERMINALS WHERE WINDS HAVE BCM SELY AND GUSTY. AT KMTN/KCHO/KMRB...
STABLE LYR HAS NOT YET BKN...AND WIND SHEAR EXISTS. THUS...WILL
CONT RMKS FOR WIND SHEAR AT THESE TERMINALS UNTIL SHALLOW STABLE
LYR ERODES.
CIGS XPCD TO RMN ABOUT 0.5-1.0 KFT THRU MUCH OF TNGT AS PCPN
PERSISTS. AS DRY AIR ARRIVES ALOFT...INSTBY XPCD TO INCR AS MSTR
CONTS TO ADVCT INTO RGN. ELEVATED INSTBY XPCD TO PROMOTE DVLPMT OF
ELEVATED TSTMS EMBEDDED IN BROADER CLUSTER OF PCPN. HAVE
INTRODUCED CB REMARKS INTO TAFS FOR KDCA/KBWI/KMTN/KIAD.
SFC TROF AXIS MOVES THRU EARLY THU MRNG...WITH WINDS BCMG WLY BY
MID-MRNG ALL TERMINALS. CIGS SHUD LIFT TO NEAR 3.0-3.5 KFT BFR
BCMG SCT LATE THU AFTN.
THE CURRENT LOW PRESSURE SYSTEM WILL MOVE WELL NE OF THE MID ATLC ON
THU...THOUGH GUSTY WINDS WILL REMAIN SETTLED OVER THE MID ATLC THRU
MUCH OF THE DAY. BY LATE THU...WINDS WILL BEGIN TO SUBSIDE W/ A
RECOVERY DAY ON FRI...AHEAD OF THE NEXT SYSTEM. BY EARLY SAT...A
LIGHT MIX OF RAIN/SNOW MAY BE POSSIBLE AS THE LOW PRESSURE SYSTEM
PASSES OFF THE EAST COAST...BUT A BACKEDGE AREA OF PRECIP PUSHES
ACROSS THE CAROLINAS AND UP INTO THE MID ATLC. INTO EARLY SUN...THIS
ACTIVITY WILL BE WELL E OF THE AREA AND QUIET CONDITIONS FOR EARLY
NEXT WEEK.
&&
.MARINE...
GALE WRNG CONTS TNGT FOR MOST ZONES IN CHSPK BAY. HAVE RMVD WRNG
FOR PATAPSCO RVR. UPPER AND MIDDLE POTOMAC AND PATAPSCO RVR WILL
RMN IN SMALL CRAFT ADZY. WINDS INCRG TO GALE FORCE THIS EVE AS
PRESSURE GRADIENT BCMS TIGHTER AMID APRCHG LOPRES. PREV DISCUSSION
FOLLOWS...
LOW PRES TRACKING NE LATE THIS AFTN/EVE WL PUSH WINDS UP TO SCA
LVLS...THEN PTNLY REACHING GALE CRITERIA DURG THE OVRNGT HRS...
DROPPING BACK TO A SOLID SCA FOR THU.
WINDS WILL DECREASE BY LATER IN THE DAY THU AND STAY FAIRLY LIGHT
INTO THE WEEKEND...THO ANOTHER LOW PRESSURE SYSTEM WILL PASS OFF THE
ATLC COAST ON SAT...POSSIBLY BRINGING BACK SCA CONDITIONS THIS
WEEKEND. HIGH PRESSURE WILL THEN BUILD IN FOR EARLY NEXT WEEK.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR DCZ001.
MD...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR MDZ011-013-014-
016>018.
VA...FLOOD WATCH UNTIL 7 AM EST THIS MORNING FOR VAZ057.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 6 PM EST THIS
EVENING FOR ANZ530>534-537-539>543.
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR ANZ530>534-537-
539>543.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ535-
536-538.
&&
$$
UPDATE...LISTEMAA
