MESOSCALE PRECIPITATION DISCUSSION 0628
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 PM EDT SAT AUG 05 2017

AREAS AFFECTED...VT...NH...WESTERN ME...WESTERN MA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 051645Z - 052200Z

SUMMARY...NORTHEAST TRAINING CELLS ALONG SLOW EASTWARD MOVING
FRONTAL BOUNDARY MAY POSE FLASH FLOOD THREAT PARTICULARLY IN
ROUGHED TERRAIN.

DISCUSSION...EXPERIMENTAL GOES-16 WV LOOP DEPICTS STRONG HEIGHT
FALLS/DPVA FROM APPROACHING SHORTWAVE ACROSS SW QUEBEC WITH A
TRAILING TROF ANGLED BACK ACROSS CENTRAL NY.  THIS LIES COINCIDENT
WITH THE SURFACE FRONT...ALLOWING FOR DEEP UNIDIRECTIONAL FLOW
SUPPORTING A TRAINING PROFILE WHILE THE FRONT SLOWLY PROPAGATES
ABOUT 5-10KTS EASTWARD.  GOES-16 VISIBLE LOOP CONTINUES TO HAVE
CLOUDED CONDITIONS WHICH HAS LIMITED SURFACE HEATING...THOUGH
BREAKS HAVE BEEN INCREASING FOR SOME FILTERED INSOLATION TO OCCUR
SUPPORTING SOME LOW 70S SFC TEMPS WITH TDS IN THE MID TO UPPER
60S. THIS HAS ALLOWED FOR SOME LOW LEVEL INSTABILITY TO OCCUR WITH
MLCAPES REBOUNDING TO 750 J/KG.

AS SUCH RECENT RADAR/VIS AND LIGHTNING NETWORK DETECT SOME
CONVECTIVE DEVELOPMENT OVER THE NORTHERN HUDSON VALLEY. DEEP
SOUTHERLY MOISTURE TRANSPORT HAS ALSO MOISTENED THE LOWER VERTICAL
PROFILE IN A NARROW AXIS ACROSS CENTRAL NEW ENGLAND INTO VT ATTM
WITH TPWS OF 1.5-1.75".  THIS SHOULD BE SUFFICIENT TO HAVE FAIRLY
EFFICIENT RAINFALL WITH RATES UP TO 1.5"/HR.  GIVEN TRAINING
PROFILE THIS MAY SUPPORT 1-2" TOTALS ACROSS CENTRAL VT/NH AS RATES
INCREASE IN EFFICIENCY WITH INCREASED INSTABILITY.  THIS FALLS IN
LINE WITH RECENT HRRR/HRRRX RUNS. GIVEN COMPLEX TERRAIN AND LOW
FFG VALUES (MAINLY ACROSS VT) THERE THE THREAT FOR FLASH FLOODING
REMAINS POSSIBLE.

ISOLATED HIGHER TOTALS MAY BE POSSIBLE WITH SOME POTENTIAL FOR
PRE-FRONTAL CONVECTION DEVELOPING JUST NORTH OF SUBTLE MCV NEAR NW
CT/CENT MA BORDER AT THIS TIME.  INCREASED CONVERGENCE ON THE
NORTHERN PORTION OF THE CIRCULATION HAS SPARKED WEAK CELLS BUT
CLOUDED CONDITIONS LIKELY WILL LIMIT THIS POTENTIAL ACROSS NH/W ME
BUT BEARS WATCHING.

GALLINA

ATTN...WFO...ALY...BOX...BTV...CAR...GYX...

ATTN...RFC...NERFC...

LAT...LON   46487020 46296980 45756982 44467010 43617053
            42887087 42487127 42187213 42327346 42607375
            43317342 44737266 45227211 45627132 46217066