Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 011013
SWOMCD
SPC MCD 011013
MEZ000-011415-

MESOSCALE DISCUSSION 1861
NWS STORM PREDICTION CENTER NORMAN OK
0413 AM CST THU DEC 01 2016

AREAS AFFECTED...NORTHERN MAINE

CONCERNING...HEAVY SNOW

VALID 011013Z - 011415Z

SUMMARY...HEAVY SNOWFALL RATES GENERALLY IN THE 1-2 INCHES PER HOUR
RANGE ARE FORECAST DURING THE 1030-1430 UTC PERIOD ACROSS NORTHERN
PARTS OF MAINE.

DISCUSSION...RADAR MOSAIC EARLY THIS MORNING SHOWS A LARGE
PRECIPITATION SHIELD ACROSS VT/NH NORTHWARD INTO MAINE.  THE
PRECIPITATION IS ASSOCIATED WITH A NORTHEAST-MIGRATING MID-LEVEL
SHORTWAVE TROUGH LOCATED OVER THE ADIRONDACKS AND THE ST. LAWRENCE
VALLEY.  VEERING AND STRENGTHENING OF FLOW IN THE LOWEST 6-KM...PER
KCBW VAD DATA...IMPLIES STRONG WARM AIR ADVECTION AND SUBSTANTIAL
ISENTROPIC LIFT ATOP A COOL DOME LOCATED OVER NORTHERN NEW ENGLAND.
MODEL GUIDANCE SUGGESTS FRONTOGENETIC FORCING WILL MAXIMIZE DURING
THE 11-14 UTC PERIOD IN THE H7-H6 LAYER COINCIDENT WITH DYNAMIC MID-
TO UPPER-LEVEL FORCING VIA DCVA.  0930 UTC GPS PRECIPITABLE WATER
OVER SOUTHERN COASTAL MAINE WAS AROUND 1 INCH...AND WHEN COUPLED WITH
THE MAGNITUDE OF UPWARD VERTICAL MOTION...WILL PROBABLY RESULT IN
LIQUID-EQUIVALENT PRECIPITATION RATES OF 0.10-0.25 INCH PER HOUR.

RAP FORECAST SOUNDINGS SHOW A DEEP ISOTHERMAL LAYER GENERALLY AT OR
SLIGHTLY BELOW FREEZING WHICH SHOULD SUPPORT HEAVY/WET DENDRITIC
SNOW.  BOTH EXPERIMENTAL OMEGA*PW*RH /OPRH/ GUIDANCE FROM THE
RAP/NAM AND SREF CALIBRATED HOURLY SNOWFALL RATES IMPLY RATES IN THE
1-2 INCHES PER HOUR RANGE BEGINNING BY 11 UTC AND ENDING DURING THE
14-15 UTC PERIOD.

..SMITH.. 12/01/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...CAR...

LAT...LON   46296780 46067017 46597008 47506936 47386812 46836761
            46296780




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