Graphic for MPD #0422
MESOSCALE PRECIPITATION DISCUSSION 0422
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1016 AM EDT SAT JUL 01 2017

AREAS AFFECTED...EASTERN UPSTATE NY...VT...NH...WESTERN ME

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

VALID 011415Z - 011915Z

SUMMARY...ANOMALOUSLY MOISTURE RICH ENVIRONMENT WITH POTENTIAL OF
TRAINING CELLS NEAR/OVER SATURATED GROUNDS AND COMPLEX TERRAIN
POSE FLASH FLOODING THREAT.

DISCUSSION...EXPERIMENTAL GOES-16 WV SUITE DEPICTS HIGHLY
ELONGATED MID-LEVEL SHEAR AXIS/SHORTWAVE NE EASTERN LAKE ONTARIO
EXTENDING SOUTHWEST TOWARD WESTERN PA.  WV LOOP ALSO DENOTES NEW
ENGLAND WITHIN A WELL DEFINED ANTICYCLONIC FLOW REGIME ALOFT
SUPPORTING MODEST DIFFLUENCE AHEAD OF APPROACHING STRONGER JET
STREAK OVER OHIO VALLEY AS WELL AS WITHIN THE FAR SW EXTREMITIES
OF WEAKER EXITING JET STREAK THROUGH N ME/SE CANADA.   THIS SETUP
HAS SUPPORTED MULTIPLE STREAMS OF MOISTURE TO REACH THE AREA WITH
CIRA LAYERED PW PLOTS SHOWING LEAF SHAPE MID TO UPPER LEVEL
MOISTURE POCKET COINCIDENT WITH MODEST SHIELD OF CLOUDS/MODERATE
RAIN SHIELD OVER N AND WESTERN NY ATTM.  ADDITIONALLY... SFC-850
MB LAYER SHOWS AMPLE MST FLUX/PUMPING ALONG THE MID-ATLANTIC
SEABOARD AND HUDSON CANYON REGION OFF THE ATLANTIC DIRECTING
MOISTURE TO THE VICINITY THROUGH THE HUDSON VALLEY.  AS SUCH THERE
ARE POCKETS OF AOA 2.0" TPW CONVERGING TOWARD NORTHER NEW ENGLAND
THROUGH MID-AFTERNOON.  

GOES-16 VISIBLE LOOP ALSO DEPICTS A DISTINCT EAST-WEST ORIENTED
LOW TO MID LEVEL CONVERGENCE BAND FROM THE NH COASTLINE ACROSS S
VT/MOHAWK VALLEY TO NEAR BEST MID-LEVEL VORT CENTER/TWIST JUST
EAST OF BUF.  RECENT UPTICK WAS NOTED WITH ONGOING CONVECTION
ENTERING VT AS WELL AS S ONIDA COUNTY NY...THIS BAND ALSO APPEARS
TO DEMARCATE HIGHER INSTABILITY GRADIENT WITH SBCAPES BEGINNING TO
REACH 1000 J/KG PER RAP AND 3HR RATES OVER 600 J/KG THROUGHOUT THE
AREA SOUTH OF THIS BOUNDARY.  

AS THE MID-LEVEL WAVE TRACKS THROUGH NW AND N NY...STEERING FLOW
ALONG THIS BOUNDARY ALONG WITH ORIENTATION OF CONVECTIVE
DEVELOPMENT MAY SUPPORT A TRACK FOR TRAINING CONVECTION ACROSS S
CENTRAL VT/CENTRAL NH INTO WEST CENTRAL ME.  EXPECTED CONVECTIVE
GROWTH BASED ON INCREASED INSOLATION DOWNSTREAM IN NH/ME POSES
GREATEST THREAT AS CONVECTIVE DEPTH INCREASES WITH THIS HEATING. 
HI-RES GUIDANCE HAS A BIT OF DISCREPANCY IN LATITUDE OF THIS
TRAINING BAND... CURRENT TRENDS (PARTICULARLY ON SOUTHERN EDGE OF
DIFFERENTIAL HEATING BOUNDARY) SUPPORT THE NSSL-WRF/ARW EVOLUTION
AND TRACK AND AS SUCH POSES THE GREATEST RISK FOR FLASH FLOODING
AS RAIN RATES INCREASE TO 1.5-2.0"/HR LEADING TO SWATHS OF 2-4"
TOTALS THROUGH 21Z.

THOUGH THERE REMAINS SOME CONCERN THAT A MORE NORTHERLY TRACK
ACROSS THE CENTRAL ADIRONDACK MOUNTAINS INTO N VT MAY EXIST. 
GIVEN PRIOR BOUTS OF HVY RAINS/FLOODING WITHIN THE LAST WEEK
(300-400% OF NORMAL IN LAST 7 DAYS PER AHPS) THERE IS A HIGHER
SUSCEPTIBLE TO ENHANCED RISK OF FLASH FLOODING WITH GREATER RUNOFF
GIVEN SATURATED/HYDROPHOBIC GROUND CONDITIONS.   

GALLINA

ATTN...WFO...ALY...BGM...BTV...BUF...GYX...

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

LAT...LON   45037027 44366985 43347129 42887318 42677445
            42647522 42817605 43577586 44647406 44907221
           


Last Updated: 1016 AM EDT SAT JUL 01 2017