WPC Met Watch |
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Mesoscale Precipitation Discussion: #0466 (2020) |
(Issued at 314 PM EDT Fri Jul 10 2020
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MPD Selection |
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Mesoscale Precipitation Discussion 0466
NWS Weather Prediction Center College Park MD
314 PM EDT Fri Jul 10 2020
Areas affected...NJ...eastern PA...southern NY
Concerning...Heavy rainfall...Flash flooding possible
Valid 101914Z - 110114Z
Summary...Heavy rain associated with Tropical Storm Fay continues
to pivot inland into portions of NJ, eastern PA and southern NY.
Expect this activity to shift north through the next several
hours. With efficient rain rates, the flash flood threat will be
ongoing through the early evening.
Discussion...Bands of heavy rain will pivot into portions of
eastern PA, northern NJ and southern NY (including New York City
and western Long Island) through the next several hours.
Precipitation estimates suggest that portions of the Delmarva have
received 6 inches with this storm and southern NJ up to 4 inches.
The mid level deformation zone supports the moisture and ascent
pivoting across eastern PA and northern NJ. Precipitable water
values over 2.5 inches aided by increasing low level easterly
winds in combination with weak instability will aid in continued
embedded thunderstorm development as this activity continues
across the northern quadrant of this system.
The anomolously high moisture will move into the urban corridor
around NYC. In addition, this region has observed above normal
precipitation over the past week resulting in very sensitive
soils. Therefore, any additional rainfall will lead to flash
flooding concerns.
Multi-model guidance is highlighting portions of northern NJ into
southern NY receiving an additional 2-4+ inches with rain rates of
near 1.25 inches/hour. While the speed of T.S. Fay as it increases
should help limit the overall extend of flash flooding, some of
the highest probabilities of efficient rain rates over 1
inch/hours from the 12Z HREF occur over NYC and its suburbs in NJ
and also over lower FFG. Therefore, this area remains prone to
flash flooding through the early evening.
Pagano/Petersen
ATTN...WFO...ALY...BGM...CTP...OKX...PHI...
ATTN...RFC...MARFC...NERFC...NWC...
LAT...LON 42197527 42067405 41457322 40667350 39987438
39817593 40157667 41307652
Last Updated: 314 PM EDT Fri Jul 10 2020
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