FXUS61 KBGM 090753
AFDBGM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
253 AM EST WED DEC 9 2009
.SYNOPSIS...
SNOW WILL GRADUALLY MIX WITH AND CHANGE TO RAIN THIS MORNING ACROSS
UPSTATE NEW YORK AND NORTHEAST PENNSYLVANIA. SLEET AND FREEZING RAIN
WILL BE POSSIBLE ACROSS THE WESTERN CATSKILLS THROUGH A GOOD PORTION
OF THE DAY...ALTHOUGH SIGNIFICANT ICING IS NOT ANTICIPATED AS DRY
AIR BEGINS TO WORK IN. COLD AND BLUSTERY CONDITIONS ARE EXPECTED TO
MOVE IN LATE TONIGHT...WITH LAKE EFFECT SNOW SHOWERS OVER UPSTATE
NEW YORK DEVELOPING THURSDAY NIGHT AND CONTINUING THROUGH THE
WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
STORM SYSTEM IS CRANKING ACRS THE MIDWEST THIS MRNG...WITH 987MB LOW
CENTERED JUST NORTH OF ST. LOUIS. LARGE SWATH OF SNOW HAS MVD INTO
UPSTATE NY AND EXTENDS SOUTH INTO SRN/CNTRL PA. SUPPLY OF CLD AIR
COURTESY OF SFC HIPRES HAS SET UP ACRS THE CWA...WITH DWPTS STILL NR
20 OVR EASTERN SXNS. 00Z SOLNS HAVE TRENDED JUST A LITTLE CLDR AND
THIS CERTAINLY SEEMS REASONABLE GIVEN CURRENT CONDS.
LATEST RUC/NAM/GFS BUFKIT SNDGS INDICATED ALL SNOW INTO NEPA THRU
09Z...THEN BEGINNING TO MIX WITH SLEET AT LOWER ELEVATIONS AND -FZRA
ABV 1500FT. THIS TRANSITION WILL TAKE PLACE SLOWLY THRU 14Z...THEN CHG TO
ALL RAIN BTWN 14Z-16Z. P-TYPE A LITTLE TRICKY IN THE POCONOS AS CLD
AIR POTENTIALLY GETS LOCKED IN ACRS THE HIGHER TERRAIN FOR A TIME
THIS MRNG. THUS...HV PLAYED ARND A LITTLE WITH THE WORDING AND TRIED
TO TIME TRANSITION VIA HRLY WX GRIDS THRU ABOUT 16Z.
FURTHER NORTH INTO TWIN TIERS...EXPECT A GRADUAL CHG-OVR AFT 12Z
WITH MODERATE SNOW UP UNTIL THEN. AS WARM LAYER WORKS ITS WAY
NORTHWARD SNOW WILL MIX WITH SLEET THRU 16Z FOR AREAS BTWN THE
BORDER AND THE NEW YORK THRUWAY THEN CHG TO RAIN AFT THIS TIME.
POCKETS OF FZRA WILL BRIEFLY BE POSSIBLE ACRS HIGHER TERRAIN THRU
THIS TIME AS WELL.
AREAS FM THE MOHAWK VLY DOWN INTO WRN CATS WILL HANG ONTO FROZEN
PCPN THE LONGEST...POSSIBLY UNTIL 18Z OR SO. WITH FCST QPF UPWARDS
OF 0.75 INCHES FOR TODAY WARNING CRITERIA IS NOT OUT OF THE QUESTION
FM ABOUT NRN ONEIDA DOWN INTO OTSEGO AND EASTERN DELAWARE.
HV OPTED NOT TO UPGRADE THESE AREAS AT THIS TIME. STILL SOME
QUESTION AS TO HOW MUCH OF A MIX WILL OCCUR AFT 16Z AS SOME AREAS
MAY TRANSITION TO SLEET/-FZRA BY NOON. THIS WUD CUT DOWN ON SNOW
AMNTS AND MAY RESULT IN AMNTS FALLING JUST SHORT OF CRITERIA WITH
ACCUMS NR 6 INCHES. ONE OTHER CAVEAT THAT HAS BEEN EVIDENT SINCE
LAST NIGHT/S MODEL RUNS IS THE HEIGHT OF THE DENDRITE LAYER. SNOW
GROWTH REGION BTWN 15-20KFT LEADS ME TO BELIEVE THAT SNOW WILL BE
MORE ON THE ORDER OF FINE NEEDLES AND MAY NOT ACCUMULATE AS RAPIDLY
AS WOULD BE NEEDED FOR 7+ INCHES. HWVR TREMENDOUS OMEGA FIELDS MAY
BE ENUF TO OVERCOME THAT AND WILL HV TO KEEP A CLOSE EYE ON AMNTS
ACRS THE MOHAWK VLY/WRN CATS THIS MRNG.
ONE WORRISOME TREND IS MODELS DVLPNG MID-LVL FRONTOGENESIS OVR TWIN
TIERS AND CATSKILLS BTWN 09Z-12Z. VRY STRONG SE LL FLOW OF 70-80KTS
WILL RESULT IN TREMENDOUS LIFT AND LKLY THE HEAVIEST PD OF SNOW DRG
THIS TIME. SNOWFALL RATES MAY EASILY TOP ONE INCH PER HR DRG THIS
TIME.
BY AFTN...MOST AREAS WILL TRANSITION OVR TO ALL RAIN WITH POSSIBLE
EXCEPTION OF FAR ERN CNTYS. BUFKIT SNDG FOR KUCA INDICATES A PD OF
-FZRA FOR HIGHER ELEVATIONS FOR A GOOD PART OF THE DAY. ALTHO PCPN
WILL BE DIMINISHING AS DRY SLOT MVS IN...STILL ENUF MOISTURE
LINGERING FOR A CHC OF -FZRA BTWN 18Z-00Z.
AS IF P-TYPE IS NOT ENUF...DRY SLOT WILL WORK IN THIS AFTN ALONG
WITH A VRY UNSTABLE MID-LAYER WITH 700-500MB LAPSE RATES OF > 7 C/KM.
THIS MAY GIVE THE AREA ISOLD THUNDER BUT WILL KEEP IT OUT OF THE
GRIDS FOR NOW TO CUT DOWN ON THE BULK...ESPECIALLY GIVEN THE SMALL
LIKELIHOOD.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
EXPECT A RAIN/SNOW MIX OVR THE AREA THIS EVNG BFR BL COOLS ENUF FOR
ALL SNOW AFT 03Z. FLOW WILL ALIGN FM 240-250...KEEPING LK EFFECT
WELL NORTH OF FA INITIALLY. MAY SEE SNOW SHOWERS DROP INTO FINGER
LKS TWD DAYBREAK BUT CHCS OF ANYTHING SIGNIFICANT ARE SLIM TO NONE
THRU TONIGHT AS SHEAR IS VRY STRONG AND FLOW STILL SWRLY ENUF TO
KEEP IT MORE CONFINED ALONG THE LAKE SHORE.
SW WINDS WILL INCRS LATE TONIGHT AND CONTINUE OVER THE NEXT 24 HRS.
MOS GUIDANCE AND BUFKIT SNDGS FOR LK PLAIN INDICATING POTENTIAL FOR
WIND ADVISORY AS PLENTY OF LOW-LVL MIXING WILL BE PRESENT AND WINDS
JUST OFF THE SFC INCRS TO 35 AND EVENTUALLY NR 40KTS DRG THE DAY
THUR AND INTO THUR NGT. WITH TIMING STILL 18-24 HRS AWAY AND WINTER
HEADLINES CURRENTLY IN PLACE...WILL PASS ON ISSUING WIND HEADLINES
AT THIS TIME. HWVR WILL KEEP WORDING IN HWO AND ALLOW NEXT SHIFT TO
ISSUE ONCE OTHER HEADLINES EXPIRE.
FLOW NEVER QUITE ALIGNS ITSELF TO BE FAVORABLE FOR LES ACRS NRN
ZONES ON THURSDAY PER LATEST NAM GUIDANCE. WILL CONT TO ADVERTISE
SCT SNOW SHOWERS FOR FINGER LKS AND MOHAWK VLY BUT NOTHING
SIGNIFICANT EXPECTED DRG THE DAY.
MAY FINALLY SEE LE DROP INTO NRN ONEIDA THUR NGT...ALONG WITH LK
ERIE BAND EXTENDING INTO FINGER LKS. ALTHO TOO EARLY FOR ANY
HEADLINES...WILL ALSO MENTION LK EFFECT SNOW FOR TUG HILL IN HWO AS
IT MAY BE AN EXTNDD PD OF LAKE SNOWS IN THE AREA THRU THE END OF THE
SHORT TERM.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
WILL USE THE HPC MEDIUM RANGE GUIDANCE FOR THIS PERIOD AS THE LONG
RANGE EXPERTS AGAIN FAVOR THE EUROPEAN MODEL AND IT/S ENSEMBLES AS A
BEST FIT SOLUTION. A COLDER THAN NORMAL PERIOD IS EXPECTED...BUT NO
MAJOR SYSTEMS ARE ON THE NEAR HORIZON..WITH JUST MINOR OCCURRENCES
OF LIGHT SNOW SHOWERS OR FLURRIES.
HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC STATES BY SATURDAY
MORNING WILL CURTAIL THE LONG DURATION LAKE EFFECT SNOW THAT WILL
HAVE BEEN OVER THE LOWER LAKES FOR MUCH OF THIS WEEK. A WEAK LOW
PRESSURE SYSTEM DEVELOPING ALONG THE SOUTHEAST COAST SAT NITE-SUNDAY
APPEARS TO TRACK FAR ENOUGH EAST FOR LITTLE OR NO CONCERN...BUT WILL
SUGGEST A LOW CHC POP ACROSS NEPA TO ACCOUNT FOR UNCERTAINTY OF
POSSIBLE WESTWARD TREND IN TRACK OF THIS LOW. SOMEWHAT UNSETTLED
WEATHER THEN CONTINUES INTO EARLY NEXT WEEK WITH A WEAK COLD FRONT
BRINGING A CHANCE OF SNOW SHOWERS OR FLURRIES ON MONDAY...FOLLOWED BY A
CHANCE OF LAKE EFFECT SNOW SHOWERS ACROSS THE NORTHERN NY COUNTIES
ON TUESDAY. LOOKING AHEAD TO THE MIDDLE OF NEXT WEEK...SEVERAL OF
THE MEDIUM RANGE MODELS CONTINUE TO HINT AT A SIGNIFICANT COASTAL
LOW PRESSURE SYSTEM DURING THE WEDNESDAY-THURSDAY TIME FRAME. OF
COURSE THERE ARE VARYING DETAILS IN TRACK/STRENGTH...BUT THE THING
TO TAKE AWAY FROM THIS IS THAT THE CONSISTENCY IN THE LONG RANGE
GUIDANCE SUGGESTS SOME KEY GLOBAL SIGNAL IS BEING LATCHED ONTO AND
THESE MODEL TRENDS WILL BE INTERESTING TO WATCH.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
VFR CONDITIONS TO START WITH A MID DECK BY 06Z. BETWEEN 05Z- 07Z,
MODERATE SNOW WILL OVERSPREAD ALL THE TERMINALS FROM SOUTH TO
NORTH. BRIEF PERIOD OF AN HOUR OR TWO OF MVFR CONDITIONS WITH
START OF SNOW BEFORE FLIGHT RESTRICTIONS WILL DROP RAPIDLY TO
LIFR WITH LOW CIGS/VSBY DUE TO SNOW. PRECIP WILL TRANSITION 10 TO
14Z FROM SW TO NE...TO A BRIEF MIX OF FREEZING RAIN/SLEET THEN
QUICKLY TO RAIN MOST AREAS BY MID MORNING. AT KRME, MIXED PRECIP
MAY CONTINUE UNTIL 20Z. EVEN THOUGH VSBYS WILL IMPROVE ONCE CHANGE
OUT OF SNOW CIGS WILL REMAIN IFR.
E/SE WINDS AT START 5 KTS OR LESS INCREASING TO 12 KTS BY 05Z.
FURTHER INCREASES TO 15 KNOTS WITH GUSTS TO 25 KNOTS WED MORNING.
SOUTH TO SW WINDS AROUND 10 KNOTS WITH GUSTS TO 20 KNOTS WEDNESDAY
AFTERNOON.
OUTLOOK...
WED EVENING...MVFR/IFR IN RAIN SHOWERS QUICKLY CHANGING TO SNOW
SHOWERS FROM W TO E. STRONG FRONT WITH WINDS SHIFTING TO THE
SOUTHWEST AND GUSTY.
THURSDAY THROUGH SATURDAY...OCCASIONAL MVFR/IFR IN LAKE EFFECT
SNOW SHOWERS PRIMARILY KRME/KSYR. REST OF AREA PRIMARILY MVFR/VFR.
SUNDAY...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR PAZ038>040-
043-044-047-048-072.
NY...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ009-
015>018-022>025-036-037-044>046-055>057-062.
&&
$$
SYNOPSIS...PVN
NEAR TERM...PVN
SHORT TERM...PVN
LONG TERM...10
AVIATION...RRM/TAC
