WPC Met Watch |
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Mesoscale Precipitation Discussion: #0715 (2019) |
(Issued at 125 PM EDT Wed Aug 07 2019
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MPD Selection |
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Mesoscale Precipitation Discussion 0715
NWS Weather Prediction Center College Park MD
125 PM EDT Wed Aug 07 2019
Areas affected...Northern Mid-Atlantic
Concerning...Heavy rainfall...Flash flooding possible
Valid 071723Z - 072323Z
Summary...Prefrontal convective thunderstorms will continue to
develop and generally lift northeast across much of the interior
northeast and I-95 corridor this afternoon. These storms may
produce rain rates of 1-2 inches per hour and lead to an isolated
flash flooding this afternoon with perhaps a greater coverage
threat this evening.
Discussion...Scattered thunderstorms have developed in broad
southwest mean flow across much of the northeastern CONUS ahead of
a cold front over the eastern Great Lakes as well as an MCV over
the eastern WV panhandle this afternoon. This area extends east to
an ocean breeze boundary over NJ. Upwind propagation vectors are
5-10kt and in the same direction as the 25kt southwesterly deep
layer mean wind which indicates slow movement despite the decent
flow. PW values vary from around 1.5 inches over the DC metro area
to 1.8 inches over CT which is about one standard deviation above
normal. Precipitation across this area has been generally
scattered over the past week with the heaviest in southern NY
state to NYC. Therefore, flash flood guidance is generally high
outside urban areas. However, given the high urbanization of this
area, as well as forcing from the MCV a flash flood threat exists
from the DC metro into MA.
The 12Z HREF shows the highest probability for two inches in one
hour both over northern NJ and ahead of the MCV along the MD/PA
border through this evening with lesser risk farther north. Given
the higher PW in southern New England and same general flow, the
isolated flash flood threat exists there. This isolated flash
flood threat expands in coverage this evening as the cold
front/embedded surface lows approaches from the west and a
subsequent discussion/threat outlook looks warranted late this
afternoon.
Jackson
ATTN...WFO...ALY...BGM...BOX...CTP...LWX...OKX...PHI...
ATTN...RFC...MARFC...NERFC...
LAT...LON 42557238 42147116 41387139 40667335 40247404
39817441 39667534 39077594 38797651 39517783
40667702 41527477
Last Updated: 125 PM EDT Wed Aug 07 2019
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