Mesoscale Precipitation Discussion 0544
NWS Weather Prediction Center College Park MD
100 PM EDT Fri Jul 27 2018

Areas affected...Southeast NY...VT...NH...Northern ME...Western
MA...Ext Northeast CT...

Concerning...Heavy rainfall...Flash flooding possible

Valid 271700Z - 272200Z

SUMMARY...Deepening moisture profile, instability to support
efficient rainfall processes with some minor training possible. 
Complex terrain and some back-building pose possible flash
flooding conditions this afternoon/evening.

DISCUSSION...Deep southwest to northeasterly flow regime along
southeast periphery of deep closed upper low over northeast
Ontario exists across the Northeast.  Right entrance to 80kt+ 3H
Jet provides broad scale ascent as well as a tightening of the
narrow moisture/ instability plume that extends from northern NJ
to the Rooftop of ME. Currently, RAP analysis depicts the axis of
MLCAPEs of 1000-1500 J/Kg coincident with total PWAT s over 1.5"
which is forecast to increase as CIRA LPW loop suggests continued
advection mainly in the lower to mid-level layers. 

Current Goes-16 Visible imagery shows TCU to CB phase maturing
across the Hudson Valley, the NH/VT Connecticut River Valley and
along the Canadian/NH/ME boarder with TCU filling between.   Cores
are fairly narrow at this point but will likely continue to expand
with strong wet microbursts given overall strength of upper flow,
but these bursts will come with 1.0-1.5" totals in short duration.
 Given the deep unidirectional flow, training is possible
especially early before some cold pools develop and eastward
propagation slowly advances the line.  Still, even after the
propagation, rates will continue to increase and pose rain totals
in the 1.5-2.5" range, which is possible to produce localized
flash flooding especially in steeper sloped terrain. 

Gallina

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

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

LAT...LON   47376830 46536785 44487034 42547196 41687320
            41277412 41367454 41767500 42357499 43677341
            45227146 47186974