Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 241048
SWOMCD
SPC MCD 241047
MAZ000-NHZ000-RIZ000-CTZ000-VTZ000-241645-

MESOSCALE DISCUSSION 0041
NWS STORM PREDICTION CENTER NORMAN OK
0447 AM CST SAT JAN 24 2015

AREAS AFFECTED...PORTIONS OF MA...RI...NERN CT...AND SRN NH

CONCERNING...HEAVY SNOW

VALID 241047Z - 241645Z

SUMMARY...HEAVY SNOW WILL CONTINUE TO OVERSPREAD PORTIONS OF SERN
NEW ENGLAND OVER THE NEXT SEVERAL HOURS. LOCAL SNOWFALL RATES OF 1-2
IN/HR WILL BE POSSIBLE THROUGH MID-LATE MORNING.

DISCUSSION...AS OF 10Z...REGIONAL WSR-88D MOSAIC INDICATES AN
EXPANSIVE SHIELD OF PCPN EXTENDING FROM PORTIONS OF THE MID-ATLANTIC
INTO SRN NEW ENGLAND. MDT-HEAVY PCPN IS BEING AIDED BY A BROAD AREA
OF FAVORABLE ADIABATIC ASCENT/WAA ALOFT DOWNSTREAM OF AN APPROACHING
MID-LEVEL SHORTWAVE TROUGH TRANSITING E/NE FROM THE TN VALLEY PER
09Z MESOANALYSIS. ADDITIONALLY...SFC ANALYSIS DEPICTS AN AREA OF 4-5
MB 2-HOURLY PRES FALLS NEAR/JUST OFFSHORE OF THE DELMARVA/JERSEY
SHORE...LIKELY A REFLECTION OF ENHANCED LARGE-SCALE ASCENT BENEATH A
DUAL-JET STRUCTURE ALOFT AND AHEAD OF THE APPROACHING SHORTWAVE
TROUGH. AS THE CONSOLIDATING LOW-LEVEL CYCLONE RAPIDLY DEEPENS AND
TRANSITS NE TOWARD 40N/70W...HVY PCPN WILL BE MAINTAINED BY AMPLE
WAA /EVIDENCED BY LONG...CYCLONIC LOOPING HODOGRAPHS ON KDIX AND
KOKX VWP DATA/ AND FURTHER ENHANCED BY INCREASING FRONTOGENETIC
CIRCULATIONS ALONG A DEVELOPING DEFORMATION AXIS TO THE NW OF THE
LOW.

1030Z KBOX DUAL-POL DATA INDICATE A CURRENT THERMAL PROFILE
CONDUCIVE TO SNOW REACHING THE SFC ACROSS MOST OF THE AREA...WITH
EVIDENCE OF MIXED PHASE /I.E. MELTING AND RE-FREEZING/ CONFINED TO
THE SOUTH ACROSS LONG ISLAND AND TO THE EAST ACROSS THE
CAPE/ISLANDS. LATEST HRRR FCST SOUNDINGS AND RADAR OBS INDICATE
FURTHER WARMING OF THE LOW-LEVEL PROFILE WILL LEAD TO A TRANSITION
TO MIXED PCPN SE OF A SFZ-BOS LINE BY APPROX 13-15Z. TO THE N/W OF
THIS LINE...THERMAL PROFILES WILL LIKELY BE COLD ENOUGH TO SUPPORT
CONTINUED SNOWFALL THRU MID-LATE MORNING...ENHANCED BY ADIABATIC
COOLING FROM INCREASING VERTICAL ASCENT AND DIABATIC PROCESSES FROM
HEAVIER PCPN. AS STRONG UPWARD MOTION IS FORECAST TO BE JUXTAPOSED
WITH THE DENDRITIC GROWTH ZONE...1-2 IN/HR SNOWFALL RATES WILL BE
POSSIBLE THRU 16Z...ESPECIALLY IN THE VICINITY OF ANY BANDING
STRUCTURE THAT DEVELOPS IN CONCERT WITH THE DEFORMATION AXIS.

..PICCA/EDWARDS.. 01/24/2015

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

ATTN...WFO...GYX...BOX...OKX...ALY...

LAT...LON   42907076 43247090 43277152 42947231 42567259 41907255
            41567229 41357174 41477140 42207081 42907076



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