WPC Met Watch |
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Mesoscale Precipitation Discussion: #0720 (2018) |
(Issued at 709 PM EDT Sun Aug 26 2018
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MPD Selection |
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Mesoscale Precipitation Discussion 0720
NWS Weather Prediction Center College Park MD
709 PM EDT Sun Aug 26 2018
Areas affected...Far east central MN...Northern WI into the UP of
MI
Concerning...Heavy rainfall...Flash flooding possible
Valid 262310Z - 270210Z
Summary...Convection training along a moisture axis could produce
hourly rainfall rates near 2.00 inches over portions of northern
WI into the UP of MI into the evening hours.
Discussion...Regional radars showed a band of convection moving
slowly northward... extending from northern WI into the western UP
of MI, as cells within the band move slowly east. The storms have
formed in an axis of 1.75/2.00 inch precipitable water air (which
is about two standard deviations above the mean), and the KDLH
radar recently showed hourly rainfall rates in this band over 2.00
inches across southern Douglas and Bayfield counties in WI.
Model soundings indicated that much of the 1000-2000 J/KG of CAPE
is elevated, as the convection has formed well north of the warm
front stretching across central MN into western WI. The soundings
also indicated moisture increasing through the depth of the
column, which could be indicating that warm rain processes are
become more important. The KMPX radar showed additional convection
forming over east central MN, which is expected to track over
areas that already received heavy rainfall.
The GOES-16 clean IR loop showed tops slowly warming, so the
activity is probably peaking between now and 27/00z. The most
recent HRRR showed an axis of 2.00 to 4.00 inches of rainfall over
northernmost WI into the western portions of the UP of MI, and
based on what has occurred thus far, those amounts seem
reasonable. Three hour flash flood guidance values are as low as
1.50 inches over northernmost WI, so flash flooding is possible
where training along the band of convection occurs.
Hayes
ATTN...WFO...DLH...MQT...
ATTN...RFC...NCRFC...
LAT...LON 47438841 47128766 46688772 46488855 46139132
46089243 46209320 46439324 46459321 46959203
47209089 47408958
Last Updated: 709 PM EDT Sun Aug 26 2018
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