SPC MESOSCALE DISCUSSION 0018 FOR THE CENTRAL APPALACHIAN
MTN
REGION
CONCERNING...HEAVY SNOW...
HEAVY SNOWFALL WILL DEVELOP NEWD INTO THE CENTRAL
APPALACHIAN
REGION OF CENTRAL/NRN WV...WRN VA NWD INTO THE PANHANDLE OF
MD...SWRN AND SCENTRAL PA THROUGH 06/22Z. HEAVY SNOW WILL
COME TO
AN END ACROSS FAR ERN KY...FAR WRN VA AND SRN WV BY 06/21Z.
SNOWFALL RATES UP TO 1 INCH/HR WILL BE LIKELY WITH ISOLATED
HIGHER
RATES POSSIBLE WITH CONVECTIVE SNOWBURSTS.
THERMAL PROFILES FROM ERN KY NWD ACROSS WV/FAR WRN MD WILL
SUPPORT
SNOW...WITH STRONG UVM FORECAST TO CONTINUE THROUGH THE
FAVORABLE
DENDRITIC SNOW GROWTH LAYER. AREAS ACROSS WRN VA NWD INTO
SCENTRAL
PA...MAY SEE A BRIEF PERIOD OF FREEZING RAIN.../SEE SWOMCD
0017/...BEFORE PRECIPITATION CHANGES OVER TO MODERATE TO
HEAVY SNOW
DURING THE 18-21Z TIME FRAME. MODEL INITIALIZED FORECASTS
ALONG
WITH CURRENT RADAR IMAGERY AGREE THAT MESOSCALE
FRONTOGENETIC
FORCING WAS AIDING IN A BAND OF HEAVY SNOWFALL EXTENDING
FROM NEAR
JKL IN SERN KY NEWD TO CENTRAL WV. MODEL FORECASTS INDICATE
THAT
THIS BAND OF MID LEVEL FRONTOGENTIC FORCING WILL MOVE NEWD
ACROSS
MUCH OF WV...THE MD PANHANDLE AND INTO SWRN/SCENTRAL PA
THROUGH THE
LATE AFTERNOON. THUS...THE GREATEST THREAT FOR HEAVY SNOW
SHOULD
EXTEND ALONG AND 50 MILES EITHER SIDE OF A LINE FROM JACKSON
KY
NEWD TO STATE COLLEGE PA. ADDITIONAL OROGRAPHIC SUPPORT FOR
HEAVY
SNOW WILL EXIST ACROSS THE HIGHER TERRAIN OF ERN WV/FAR WRN
VA. VWP
DATA FROM ROA INDICATES A GRADUAL BACKING OF 850 MB WINDS
RECENTLY.
THIS WOULD SUPPORT OROGRAPHIC ENHANCEMENT...GIVEN THE
FAVORABLE
ORIENTATION OF APPALACHIAN MTNS TO LOW LEVEL WINDS.
..CROSBIE.. 01/06/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 061621
SWOMCD
SPC MCD 061620
VAZ000-MDZ000-PAZ000-WVZ000-062100-
SPC MESOSCALE DISCUSSION 0017 FOR...WRN/NRN VA...NRN
MD...SRN PA...
CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION...
...CORRECTED REFERENCE MCD NUMBER LAST LINE...
COMPLEX PRECIPITATION TYPE FCST ACROSS THE FOOTHILLS OF THE
APPALACHIANS AS STRONG WINTER STORM DEVELOPS NEWD THROUGH
THE
AFTERNOON. LATEST GUIDANCE FROM ETA AND RUC PRECIP TYPE
ALGORITHMS
SUGGESTS A NARROW AXIS OF FREEZING RAIN WILL DEVELOP QUICKLY
FROM
SOUTH-CNTRL VA NEWD...POSSIBLY AS FAR NORTH AS THE WV
PANHANDLE
DURING THE 16Z-20Z TIME FRAME. HOWEVER...MAGNITUDE OF
WARMING IN
THE 900-800 MB LAYER WILL LIKELY BE OFFSET BY INTENSE
LIFTING AND
WET BULB COOLING DURING THIS PERIOD...RESULTING IN THE
DEVELOPMENT
OF A NARROW TRANSITION ZONE AND PERHAPS EVEN A RAIN/SNOW
LINE OVER
THE REGION BY LATER THIS AFTERNOON.
LATEST ANALYSIS PLACES DEEPENING SURFACE LOW IN EXTREME NERN
GA
WITH STRONG PRESSURE FALLS ACROSS ERN NC WHERE LOW SHOULD
TRACK/REDEVELOP OVER THE NEXT FEW HOURS. SURFACE
TEMPERATURES
ACROSS MUCH OF VA WHERE ABOVE 0C ATTM EXCEPT ALONG A LYH/DAN
LINE
WHERE ONSET OF HEAVIER PCPN AND WET BULB COOLING HAS CAUSED
TEMPS
TO DROP BELOW FREEZING. THIS TREND SHOULD CONTINUE NWD
ACROSS
WRN/CNTRL VA AS INTENSE WARM/MOIST CONVEYOR BELT DRIVEN BY
40-60 KT
850 MB FLOW CONTINUES TO DEVELOP NEWD THROUGH THIS
AFTERNOON. LOW
LEVEL THERMAL GRADIENT AROUND THE 0C ISOTHERM WILL BECOME
INCREASINGLY TIGHT RESULTING IN A NARROWING EAST TO WEST
TRANSITION
ZONE BETWEEN RA/FZRA/SN. IN FACT...PCPN MAY INITIALLY START
AS A
PERIOD OF SN OR RA...PERHAPS FOLLOWED BY FZRA AS SURFACE
REACHES
FREEZING BUT WARMEST TEMPS ON NOSE OF LOW LEVEL JET MOVE
OVHD...
FOLLOWED BY WET SNOW AS LOW LEVEL TEMPERATURE PROFILE
BECOMES
NEARLY ISOTHERMAL AOB 0C. THUS EXPECT FREEZING/FROZEN PCPN
AMOUNTS
TO BE QUITE VARIABLE OVER THE REGION WITH THE HEAVIEST SNOW
TO
OCCUR WEST OF THE RA/FZRA-SNOW LINE. PLEASE REFER TO MCD
0018 AND
HPC HEAVY SNOW FCSTS FOR ADDITIONAL DETAILS.
..CARBIN.. 01/06/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 061812
SWOMCD
SPC MCD 061812
OHZ000-062200-
SPC MESOSCALE DISCUSSION 0019 FOR PORTIONS OF SRN/ERN OH
CONCERNING...HEAVY SNOW...
A BAND OF HEAVY SNOWFALL WILL SHIFT SLOWLY EWD ACROSS ERN OH
BEFORE
DIMINISHING BY 06/21Z. SNOWFALL RATES UP TO 1 INCH/HR WILL
BE
POSSIBLE.
LATEST RADAR MOSAIC SHOWS A RECENT INCREASE IN REFLECTIVITY
WITHIN
A 25 MILE WIDE BAND ACROSS SCENTRAL OH. SURFACE ANALYSIS
SHOWS THAT
THIS BAND IS COINCIDENT WITH A SURFACE PRESSURE TROUGH.
PROXIMITY
OF SURFACE-850 MB LOW TO REGION WAS LIKELY CONTRIBUTING TO
DOWNSLOPE FLOW OFF THE CENTRAL APPALACHIANS...AND FORMATION
OF THIS
TROUGH. A COMPARISON OF VWP DATA FROM WILMINGTON OH AND
CHARLESTON
WV INDICATES THAT LOW LEVEL CONVERGENCE WAS 1.5 KM DEEP.
APPROACHING MID LEVEL VORT MAX WAS AIDING IN ADDITIONAL
SUPPORT FOR
ENHANCED MESOSCALE LIFT IN THE 600-500 MB LAYER DUE TO
MODEST
FRONTOGENETIC FORCING AND DEFORMATION DEVELOPMENT.
COMBINATION OF
THESE SURFACE AND UPPER LEVEL MESOSCALE FORCING SHOULD
CONTINUE TO
SUPPORT THIS HEAVY SNOW BAND AS IT GRADUALLY MOVES EWD
ACROSS
SERN/ECENTRAL OH THROUGH 06/21Z. AS SURFACE-850 MB LOW
REDEVELOPS
ALONG THE MID-ATLANTIC COAST TOWARD 06/21Z...EXPECT
WEAKENING LOW
LEVEL WIND FIELDS/SURFACE CONVERGENCE...AND DIMINISHING
SNOWFALL
RATES WITHIN THIS SNOW BAND BY 06/21Z.
..CROSBIE.. 01/06/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 062001
SWOMCD
SPC MCD 062001
PAZ000-NYZ000-MAZ000-VTZ000-070300-
SPC MESOSCALE DISCUSSION 0020 FOR MUCH OF THE INTERIOR
NORTHEAST
CONCERNING...HEAVY SNOW...
HEAVY SNOWFALL WILL DEVELOP NEWD INTO MUCH OF NRN PA AND
SCENTRAL
NY THROUGH 07/00Z...BEFORE DEVELOPING INTO INTERIOR PORTIONS
OF
SERN/ECENTRAL NY...WRN MA AND SRN VT BETWEEN 07/00Z AND
07/03Z.
SNOWFALL RATES FROM 1 TO 2 INCH/HR WILL BE POSSIBLE.
HEAVY SNOWFALL CURRENTLY OCCURING OVER PORTIONS OF WV/SRN PA
WILL
CONTINUE TO DEVELOP NEWD IN REGION OF STRONG DEEP LAYER UVM.
GREATEST CONTRIBUTION TO MESOSCALE FORCING FOR ORGANIZED
BANDS OF
HEAVY SNOW WILL CONTINUE TO BE STRONG FRONTOGENE11TICAL LIFT
AT MID
LEVELS IN REGION OF FAVORABLE DENDRITIC SNOW GROWTH LAYER.
PORTIONS
OF NCENTRAL/NERN PA...SCENTRAL/SERN NY WILL SEE THE GREATEST
THREAT
FOR HEAVY SNOW BETWEEN 06/21Z AND 07/02Z. ACROSS INTERIOR
SERN
NY/WRN MA AND SRN VT STRONG WAA WILL CONTINUE TO WORK TO
SATURATE
THE SFC-850 MB LAYER THROUGH THE EARLY EVENING HOURS. HEAVY
SNOWFALL WILL BEGIN TO DEVELOP NEWD INTO THIS REGION BETWEEN
07/00Z
AND 07/03Z...ONCE LOW LEVELS BECOME SATURATED. GREATEST
THREAT FOR
HEAVY SNOWFALL WITH HRLY RATES FROM 1-2 INCHES WILL EXIST
WHERE
STRONGEST FRONTOGENETICAL FORCING IN THE 750 TO 650 MB LAYER
IS
MAXIMIZED ALONG AND 50 MILES EITHER SIDE OF AN AXIS FROM UNV
TO BGM
TO ALB THROUGH 07/02Z. SOME CONVECTIVE SNOWFALL WILL BE
POSSIBLE
ALONG THE ERN EDGE OF THE DISCUSSION AREA THIS EVENING FROM
NERN PA
NEWD INTO WRN MA...ALONG REGION OF 6 TO 6.5 MID LEVEL LAPSE
RATES/STRONGEST WAA. SNOWFALL RATES IN CONVECTIVE
00\AFOSSIMSNOWBURTS MAY APPROACH 2 INCH/HR.
..CROSBIE.. 01/06/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 062053
SWOMCD
SPC MCD 062053 COR
PAZ000-NYZ000-MAZ000-VTZ000-070300-
SPC MESOSCALE DISCUSSION 0020 FOR MUCH OF THE INTERIOR
NORTHEAST
CONCERNING...HEAVY SNOW...
HEAVY SNOWFALL WILL DEVELOP NEWD INTO MUCH OF NRN PA AND
SCENTRAL
NY THROUGH 07/00Z...BEFORE DEVELOPING INTO INTERIOR PORTIONS
OF
SERN/ECENTRAL NY...WRN MA AND SRN VT BETWEEN 07/00Z AND
07/03Z.
SNOWFALL RATES FROM 1 TO 2 INCH/HR WILL BE POSSIBLE.
HEAVY SNOWFALL CURRENTLY OCCURING OVER PORTIONS OF WV/SRN PA
WILL
CONTINUE TO DEVELOP NEWD IN REGION OF STRONG DEEP LAYER UVM.
GREATEST CONTRIBUTION TO MESOSCALE FORCING FOR ORGANIZED
BANDS OF
HEAVY SNOW WILL CONTINUE TO BE STRONG FRONTOGENETICAL LIFT
AT MID
LEVELS IN REGION OF FAVORABLE DENDRITIC SNOW GROWTH LAYER.
PORTIONS
OF NCENTRAL/NERN PA...SCENTRAL/SERN NY WILL SEE THE GREATEST
THREAT
FOR HEAVY SNOW BETWEEN 06/21Z AND 07/02Z. ACROSS INTERIOR
SERN
NY/WRN MA AND SRN VT STRONG WAA WILL CONTINUE TO WORK TO
SATURATE
THE SFC-850 MB LAYER THROUGH THE EARLY EVENING HOURS. HEAVY
SNOWFALL WILL BEGIN TO DEVELOP NEWD INTO THIS REGION BETWEEN
07/00Z
AND 07/03Z...ONCE LOW LEVELS BECOME SATURATED. GREATEST
THREAT FOR
HEAVY SNOWFALL WITH HRLY RATES FROM 1-2 INCHES WILL EXIST
WHERE
STRONGEST FRONTOGENETICAL FORCING IN THE 750 TO 650 MB LAYER
IS
MAXIMIZED ALONG AND 50 MILES EITHER SIDE OF AN AXIS FROM UNV
TO BGM
TO ALB THROUGH 07/02Z. SOME CONVECTIVE SNOWFALL WILL BE
POSSIBLE
ALONG THE ERN EDGE OF THE DISCUSSION AREA THIS EVENING FROM
NERN PA
NEWD INTO WRN MA...ALONG REGION OF 6 TO 6.5 DEG C/KM MID
LEVEL
LAPSE RATES/STRONGEST WAA. SNOWFALL RATES IN CONVECTIVE
SNOWBURTS
MAY APPROACH 2 INCH/HR.
..CROSBIE.. 01/06/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 062316
SWOMCD
SPC MCD 062316
CTZ000-MAZ000-VTZ000-NHZ000-MEZ000-070600-
SPC MESOSCALE DISCUSSION 0021 FOR CENTRAL NEW ENGLAND
CONCERNING...HEAVY SNOW...
HEAVY SNOW WILL DEVELOP NEWD ACROSS SRN VT...WRN/N-CENTRAL
MA...SRN
NH...AND SWRN ME BETWEEN 07/00Z-07/06Z. SNOW RATES OF 1-2
IN/HR ARE
ANTICIPATED.
DEEPENING 996MB SFC CYCLONE JUST EAST OF THE DELMARVA
PENINSULA
WILL TRACK NEWD TO BUZZARDS BAY AT 07/06Z. MOSAIC
REFLECTIVITY AT
2315Z INDICATES INTENSE PRECIPITATION ASSOCIATED WITH STRONG
DIFFERENTIAL PVA AND WARM ADVECTION MOVING NWD ALONG THE NJ
SHORE
TOWARD NEW ENGLAND...AND AN ENHANCED NARROW BAND ORIENTED
FROM
CENTRAL PA NEWD INTO THE CAPITAL DISTRICT OF NY OWING TO
MID-LEVEL
FRONTOGENESIS FORCING. THERMAL PROFILES WILL NOT SUPPORT
SNOW ALONG
THE NEW ENGLAND COASTLINE UNTIL CYCLONE MOVES EAST OF THE
REGION
DURING THE EARLY MORNING HOURS. HIGHEST SNOWFALL
ACCUMULATIONS WILL
TAKE PLACE NORTH AND WEST OF A LINE FROM PSM TO ORH TO 20 SE
POU.
MESOSCALE ASCENT OWING TO FRONTOGENESIS FORCING WILL BE
CONCENTRATED ALONG A LINE FROM PSF TO CON TO PWM...WHERE THE
HEAVIEST SNOW RATES ARE LIKELY. HEAVY SNOW OF 1-2 IN/HR ARE
EXPECTED ALONG THIS AXIS BETWEEN 03-09Z. A RAIN/SNOW MIX IS
LIKELY
FROM MIDDLESEX COUNTY MA SWWD INTO HARTFORD CT AREA...WITH
MOSTLY
RAIN IN BOS METRO THROUGH 09Z.
..BANACOS.. 01/06/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 070339
SWOMCD
SPC MCD 070339
NYZ000-MAZ000-VTZ000-NHZ000-MEZ000-070900-
SPC MESOSCALE DISCUSSION 0022 FOR ERN NY AND CENTRAL/NRN NEW
ENGLAND
CONCERNING...HEAVY SNOW...
VERY HEAVY SNOW BAND ACROSS ERN NY WILL TRANSLATE NEWD
ACROSS
SRN/CENTRAL VT...NH...AND ME THROUGH THE OVERNIGHT PERIOD.
SNOW
RATES OF 1-2 IN/HR ARE EXPECTED ACROSS PORTIONS OF THE
DISCUSSION
AREA.
STRONG AND FAST MOVING SURFACE CYCLONE JUST SOUTH OF LONG
ISLAND
WILL MOVE NEWD ACROSS SERN NEW ENGLAND AND INTO THE GULF OF
MAINE
BY 07/12Z. EXTREME SURFACE PRESSURE FALLS ARE NOTED AT
07/03Z
ACROSS ERN LONG ISLAND AND THE SOUTH COAST OF NEW
ENGLAND...ON THE
ORDER OF 10-12MB/3 HRS. THE BACK EDGE OF THE PRECIPITATION
AT 0330Z
EXTENDS FROM NYC EWD TO BID...ASSOCIATED WITH DEVELOPING DRY
SLOT.
WITH SYNOPTIC LOW OCCLUDING...THE FOCUS WILL BE ON THE
WELL-DEFINED
DEFORMATION ZONE AND PERSISTENT HEAVY SNOWFALL ON THE NWRN
PERIPHERY OF THE SYSTEM...EXTENDING AT 03Z FROM EXTREME NERN
PA
NEWD INTO THE ALB AREA...WHERE RAPID SNOW ACCUMULATIONS ARE
TAKING
PLACE. VERY STRONG SYNOPTIC-SCALE ASCENT WILL CONTINUE TO
TRANSLATE
NWD THROUGH NEW ENGLAND OVERNIGHT...AND FRONTOGENESIS
FORCING
WITHIN THE DEFORMATION ZONE WILL RESULT IN SNOW RATES OF 1-2
IN/HR.
THE AXIS OF HEAVIEST SNOWFALL THROUGH 12Z WILL BE IN A 50NM
CORRIDOR DEVELOPING NEWD FROM ALB TO CON TO LEW...WHERE HIGH
RADAR
REFLECTIVITY BAND ASSOCIATED WITH STRONG MESOSCALE FORCING
IS
FORMING.
..BANACOS.. 01/07/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...
000
ACUS11 KWNS 070730
SWOMCD
SPC MCD 070729
MEZ000-071200-
SPC MESOSCALE DISCUSSION 0023 FOR CNTRL AND ERN ME
CONCERNING...HEAVY SNOW...
BANDS OF HEAVY SNOW WITH RATES OF 1-2 INCHES PER HOUR WILL
CONTINUE
ACROSS PORTIONS OF CNTRL AND ERN ME FOR ANOTHER FEW HOURS.
THE
SNOW RATES WILL QUICKLY DECREASE AROUND 12 UTC.
MESOANALYSIS DEPICTS 990 MB SURFACE LOW BETWEEN PVD-BOS WITH
11 MB
3-HRLY PRESSURE FALL AXIS EXTENDING NEWD INTO THE GULF OF
ME.
LATEST RUC40 PROGS THE LOW TO MOVE INTO THE GULF OF ME BY 12
UTC
AND THIS SEEMS REASONABLE. STRONG DEFORMATION ZONE CONTINUES
TO
TRANSLATE QUICKLY NEWD ACROSS CNTRL NEW ENGLAND WITH
CONVECTIVE
ELEMENTS FEEDING NWD INTO DOWNEAST ME. STRONG 850-700 MB
FRONTOGENESIS AXIS IS LIKELY TO SUPPORT A 70 NM WIDE AREA OF
HEAVY
SNOW EXTENDING FROM 30 E BERLIN-25 SE GREENVILLE-30 S
HOULTON.
HEAVIER RATES ARE LIKELY TO OCCUR IN THE MOUNTAINS
NEAR/SOUTH OF
GREENVILLE EAST TO SOUTH OF HOULTON AND CLOSER TO THE COAST
FROM
WATERVILLE TO CALAIS. THE HEAVIER SNOW BANDS SHOULD DEVELOP
NEWD
INTO CNTRL/SRN NEW BRUNSWICK BETWEEN 10-12 UTC...WITH SNOW
RATES
DECREASING QUICKLY OVER ME.
..RACY.. 01/07/02
...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...