Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 190204
SWOMCD
SPC MCD 190204
NHZ000-VTZ000-190700-

MESOSCALE DISCUSSION 0036
NWS STORM PREDICTION CENTER NORMAN OK
0804 PM CST SUN JAN 18 2015

AREAS AFFECTED...PORTIONS OF NRN AND CNTRL VT

CONCERNING...HEAVY SNOW

VALID 190204Z - 190700Z

SUMMARY...RAIN WILL CONTINUE TO TRANSITION TO SNOW ACROSS THE AREA
THIS EVENING...BECOMING MODERATE TO HEAVY AT TIMES THROUGH EARLY
TONIGHT...WITH SNOWFALL RATES UPWARDS OF 1-1.5 IN/HR.

DISCUSSION...PER 0130Z REGIONAL WSR-88D MOSAIC...AN EXPANSIVE AREA
OF MDT TO LOCALLY HVY PCPN IS PROGRESSING NORTH ACROSS PORTIONS OF
NEW ENGLAND THIS EVENING. A COMBINATION OF FAVORABLE ADIABATIC
ASCENT AND INCREASING FRONTOGENETIC FORCING IS SUPPORTING THIS LARGE
AREA OF PCPN...AS THE LOW/MID-LEVEL MASS RESPONSE STRENGTHENS IN
CONCERT WITH A DEEPENING SFC CYCLONE ANALYZED OVER ERN CT AS OF 01Z.
AS THE LOW LIFTS NORTH INTO NH EARLY TONIGHT...FURTHER ENHANCEMENT
OF FRONTOGENETIC CIRCULATIONS NEAR THE MID-LEVEL DEFORMATION AXIS
WILL PROMOTE A BAND OF HEAVY PCPN EXTENDING ACROSS MUCH OF VT AROUND
03-06Z...WHICH IS IN GENERAL AGREEMENT WITH CURRENT HI-RES GUIDANCE.

WHILE PRESENT SFC TEMPS AND FORECAST LOW-LEVEL THERMAL PROFILES
APPEAR MARGINAL FOR SNOW...A COMBINATION OF FACTORS /I.E. ENHANCED
DIABATIC PROCESSES FROM HEAVIER PCPN...COOLING FROM STRENGTHENING
UPWARD VERTICAL MOTION...AND IMPROVED CAA AS THE LOW-LEVEL CYCLONE
TRANSITS NORTH THRU NH/ WILL SUPPORT A MORE WIDESPREAD TRANSITION TO
SNOW. INDEED...KCXX DUAL-POL DATA INDICATE A STEADY DESCENT OF THE
MELTING LAYER OVER THE LAST SEVERAL HOURS AND A FEW MPING OBS NOW
REPORT SNOW...IN AGREEMENT WITH THE PREVIOUS REASONING. AS
SUCH...WITH THE DEVELOPMENT OF A MORE FAVORABLE LOW-LEVEL THERMAL
PROFILE AND THE EXPECTED INTERSECTION OF STRONG UPWARD MOTION WITH
THE DENDRITIC GROWTH ZONE...SNOWFALL RATES UP TO 1-1.5 IN/HR ARE
LIKELY THIS EVENING INTO EARLY TONIGHT ACROSS PORTIONS OF NRN/CNTRL
VT...ESPECIALLY IN THE HIGHER ELEVATIONS OF THE GREEN MTNS.
THEREAFTER...THE STRONGEST FORCING FOR ASCENT AND RESULTANT AREA OF
HEAVY SNOW WILL SHIFT NORTH INTO QUEBEC LATE TONIGHT.

..PICCA/EDWARDS.. 01/19/2015

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

ATTN...WFO...GYX...BTV...

LAT...LON   45057257 45067184 45017152 44777142 44277187 43717228
            43567275 43627284 44797324 45007321 45037298 45057257



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