FXUS61 KBGM 260553
AFDBGM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
1253 AM EST THU NOV 26 2009
.SYNOPSIS...
A WEAK FRONT WILL BRING A FEW LIGHT RAIN SHOWERS AND DRIZZLE TO THE
AREA TONIGHT. DRY WEATHER WILL FOLLOW BEHIND THE FRONT ON
THANKSGIVING DAY WITH MORE UNSEASONABLY MILD TEMPERATURES. A
STRONGER SYSTEM WILL BRING SHOWERS TO THE AREA THURSDAY NIGHT.
COLDER AIR ARRIVING IN THE WAKE OF THIS SYSTEM MAY ALLOW FOR SOME
OF THE RAIN TO MIX WITH OR CHANGE TO SNOW LATE THURSDAY NIGHT AND
FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
FCST BEHAVING FOR THE MOST PART THIS EVE. STILL A FEW SHWRS DRFTG
THRU THE NRN ZONES OTRW JUST SOME PTCHY DRIZZLE AND FOG OVER THE
AREA. WILL KEEP SHWRS IN FOR A CPL MORE HRS AND XTND THE DRIZZLE
ACROSS THE ENTIRE FCST AREA OVRNGT. MPO JUST CAME IN WITH DENSE
FOG SO WILL HAVE TO WATCH OVRNGT OF THE NEED ARISES FOR AN
ADVISORY...ESP CNSDRG THE HOLIDAY TRAVEL. PRVS DISC CONTS...
MAIN UPPER-LEVEL WAVE IS PROGGED TO ROTATE THROUGH THE REGION AND
INTO EASTERN CANADA LATER THIS EVENING...WITH MOST OF THE SHOWER
ACTIVITY OCCURRING THROUGH ABOUT 10 PM.
LATER TONIGHT...LARGE-SCALE SUBSIDENCE SETS IN BEHIND THE ABOVE
MENTIONED WAVE. DESPITE THE SINKING MOTION ALOFT...MODEL SOUNDINGS
AND MOISTURE PROGS SHOW PLENTY OF LOW-LEVEL MOISTURE REMAINING.
THIS SHOULD TRANSLATE INTO RESIDUAL STRATUS CLOUDS AND SOME
ELEVATION FOG.
DUE TO ALL THE EXPECTED CLOUD COVER...TEMPERATURES ARE NOT LIKELY
TO FALL A GREAT DEAL OVERNIGHT...ONLY INTO THE UPPER 30S AND LOWER 40S.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
DRYING ALOFT WILL FOLLOW BEHIND THE SHORT WAVE THIS EVENING...
SETTING THE STAGE FOR A DRY THANKSGIVING ACROSS NORTHEAST PA AND
CENTRAL NY. HOWEVER... MODEL SOUNDINGS INDICATE THAT DRYING IN
THE 3 TO 5 KFT LEVEL WILL BE SLOW TOMORROW... WITH THE BEST CHC
FOR SOME CLEARING ACROSS NORTHEAST PA.
NEXT SYSTEM TO AFFECT THE AREA WILL ARRIVE LATER THURSDAY NIGHT.
A FAIRLY TYPICAL DEGREE OF MODEL DISAGREEMENT IS EVIDENT WITH THE
TRACK AND INTENSITY OF THIS SYSTEM AT THIS TIME RANGE. MODELS ARE
IN GENERAL AGREEMENT THAT A STRONG UPPER LEVEL SYSTEM WILL TRACK
EAST-SOUTHEAST ACROSS PA/SRN NY THURSDAY NIGHT AND FRIDAY
MORNING... THEN OFF THE COAST LATER FRIDAY. SFC LOW PRESSURE WILL
DEVELOP WELL OFF SHORE.
HOWEVER... MINOR DIFFERENCES IN THE TRACK AND DEEPENING RATE OF
THE UPPER SYSTEM WILL HAVE MAJOR EFFECTS ON THE DEVELOPMENT OF A
BAND OF MODERATE TO HEAVY PRECIPITATION NEAR AND NORTH-WEST OF THE
MID-UPPER LEVEL LOW. CURRENTLY... THE GFS IS FARTHEST NORTH
WITH THE TRACK OF THE UPPER SYSTEM... AND IS SLOWEST TO DEVELOP
THE DEFORMATION BAND ON THE NORTH-WEST SIDE OF THE LOW.
MEANWHILE... THE NAM IS FARTHEST SOUTH... DEVELOPING A DEFORMATION
BAND OF HEAVY PRECIPITATION OVER CENTRAL PA BY 12Z FRIDAY. THE
ECMWF APPEARS TO BE A COMPROMISE... TRACKING THE 500 MB LOW FROM
CENTRAL PA TO SOUTHERN NEW ENGLAND ON FRIDAY WITH MODERATELY
STRONG DEEPENING... FROM 531 DM TO 525 DM. THE 700 MB LOW IS
FORECAST TO CLOSE OFF OVER CENTRAL PA... THEN DEEPEN AS IT TRACKS
NORTHEAST. THE ECMWF DEVELOPS A DEFORMATION BAND OF MODERATE TO
HEAVY PRECIPITATION OVER CENTRAL NY AND NORTHERN PA BY 12Z FRIDAY.
THE EXACT LOCATION AND TIMING OF THE DEVLOPMENT OF THIS
DEFORMATION BAND OF HEAVIER PRECIPITATION WILL BE CRITICAL FOR OUR
AREA REGARDING BOTH PRECIPITATION AMOUNTS AND PRECIPITATION TYPE.
BOUNDARY TEMPERAUTRES ASSOCIATED WITH THIS SYTEM WILL BE GENERALLY
TOO WARM FOR SNOW THROUGH MOST OF FRIDAY... EXCEPT POTENTIALLY
UNDERNEATH ANY DEFORMATION BAND OF HEAVIER PRECIPITATION THAT CAN DEVELOP...
WHERE COOLING DUE TO MELTING AND LIFT COULD COOL TEMPERATURES
SUFFICIENTLY FOR WET SNOW... ESPECIALLY OVER HIGHER ELEVATIONS. AN
EXAMPLE OF THIS CAN BE SEEN BY LOOKING AT THE NAM FORECAST
SOUNDINGS AT IPT. IN THESE SOUNDINGS... AN ISOTHERMAL ZERO DEGREE
C LAYER FORMS DUE TO HEAVY PRECIPITATION... WHICH WOULD RESULT IN
A FEW HOURS OF HEAVY SNOW. SO... THE KEY QUESTION FOR FRIDAY IS
WHERE AND WHEN THE DEFORMATION BAND CAN SET UP.
WITH THIS HIGH LEVEL OF UNCERTAINTY... HAVE DECIDED TO PLAY THINGS
FAIRLY CONSERVATIVELY AT THIS TIME... AND AM GOING WITH SOME LIGHT
SNOW ACCUMULATIONS ACROSS MUCH OF THE AREA FROM LATE THURSDAY
NIGHT THROUGH FRIDAY NIGHT WITH MIXED RAIN AND SNOW SHOWERS. THIS
FORECAST IS FAIRLY CLOSE TO THE CURRENT HPC FORECAST... EXCEPT
THAT I PUT IN A LITTLE MORE DETAIL DUE TO ELEVATION DIFFERENCES. PRECIPITATION
SHOULD BE MAINLY LAKE ENHANCED SNOW SHOWERS DOWNWIND OF LAKE
ONTARIO BY LATE FRIDAY NIGHT WITH 850 MB TEMPERATURES EVENTUALLY
FORECAST TO FALL TO AROUND -5 OR -6 WITH A FLOW FROM AROUND 300 DEGREES.
ANY LIGHT LAKE ENHANCED RAIN OR SNOW SHOWERS SHOULD DISSIPATE ON
SATURDAY AS HIGH PRESSURE BUILDS IN.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
LITTLE CHANGE TO THE LONG TERM. MORE UNSETTLED WITH NEAR NORMAL
TEMPERATURES WHICH WILL BE MUCH COLDER THAN WHAT WE HAVE HAD
LATELY.
PREVIOUS DISCUSSION...
NW FLOW SAT NGT SHD RESULT IN A FEW MORE SHWRS OTRW HIPRES BLDS IN
SFC AND ALOFT CLRG WILL BE SHRT LIVED AS ANOTHER WV AND SFC FNT
APRCHS LATE MON AND EARLY TUE. CRNT MODEL SOLNS ARE BASICALLY A
COMPROMISE OF EARLIER RUNS WITH A PROGRESSIVE FNT BUT WITH A
DEEPENING LOW NORT OF NEW ENG. OPERATIONAL GFS IS STILL FCSTG A
DEEPER LOW AND THEN FLWS WITH MORE CAA BHD THE FNT. EITHER WAY
IT/S A QUICK SHOT OF COLD AIR BEFORE RDGG RETURNS LTR WED.
ONCE AGAIN FLWD THE LATEST HPC GUID WITH SOME MINOR TWEAKS OF THE
POPS AND TEMPS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
VERY DIFFICULT FORECAST SITUATION SETTING UP. THE MAIN FACTORS
INCLUDE SATURATED TERRAIN FROM EARLIER RAINS, AN OCCLUDED FRONT
APPROACHING FROM THE SOUTHWEST, A MARINE LAYER ENCROACHING FROM
THE SE AGAIN, ALONG WITH A LARGE AREA OF CLEARING WHICH THREATENS
TO OVERTAKE LARGELY VFR CLOUD COVER ACROSS NY/PA TERMINALS.
LESS CLOUDS IN THE FINGER LAKES TO KELM HAVE ALLOWED IFR RADIATIONAL
FOG TO FORM. THIS SHOULD CONTINUE THERE AND WILL PROBABLY WORSEN.
THE MARINE LAYER HAS GOTTEN TO KMPO AND KMSV SO KAVP SHOULD HAVE
AT LEAST MVFR CIGS BY 09Z, POSSIBLY DROPPING TO IFR AROUND 11Z.
THIS MOISTURE WILL MOVE FURTHER NW INTO THE NY TAF SITES BY 11Z.
KSYR WILL BE LAST TO FALL IF IT DROPS TO MVFR AT ALL. KBGM WITH
ITS HIGHER ELEVATION COULD DROP TO IFR AROUND 12Z. VSBYS COULD
ALSO DROP TO MVFR. LATE THIS MORNING SLOW IMPROVEMENT TO VFR
AGAIN. THIS EVENING THE FRONT MOVES IN WITH SHOWERS AND MVFR
CONDITIONS.
WINDS 5 KTS OR LESS FROM THE SE TO S EARLY THIS MORNING. DURING
THE DAY AROUND 5 KTS THEN THIS EVENING A WIND SHIFT WITH THE FRONT
TO W AND NW.
OUTLOOK...
LATE THUR NGT-FRI...MVFR/IFR RESTRICTIONS LIKELY...IN RAIN AND/OR
WET SNOW.
FRI NGT-SAT...MVFR/IFR RESTRICTIONS AGAIN POSSIBLE...IN
RAIN/SNOW SHOWERS.
SUN...IMPROVEMENT TO VFR LIKELY.
MON...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MSE
NEAR TERM...DGM/MSE
SHORT TERM...MSE
LONG TERM...DGM/TAC
AVIATION...TAC
