From Dumas Walker@21:1/175 to All on Friday, September 27, 2024 08:03:00
AWUS01 KWNH 271006
FFGMPD
NCZ000-SCZ000-271600-
Mesoscale Precipitation Discussion 1075
NWS Weather Prediction Center College Park MD
605 AM EDT Fri Sep 27 2024
Areas affected...coastal/eastern SC into central/southern NC
Concerning...Heavy rainfall...Flash flooding possible
Valid 271004Z - 271600Z
SUMMARY...Possible training and repeating of heavy rain associated
with Tropical Storm Helene could produce localized flash flooding
from central to coastal SC into central/southern NC through 16Z.
The potential for 1-3 in/hr rainfall rates will exist.
DISCUSSION...Regional radar imagery at 0950Z showed an outer rain
band to the east of T.S. Helene focusing from the offshore waters
of SC across the Charleston metro into central SC. Numerous cells
were observed to be repeating across the region with brief
training supporting MRMS-derived rainfall rates occasionally over
1 in/hr. These cells were located with a very moist environment
(2.3 to 2.6 inch precipitable water values) and MLCAPE of 500-1500
J/kg via the 09Z SPC mesoanalysis.
As Helene continues a northward to an eventual northwestward
motion this morning, bands of heavy rain on the east side of
Helene are expected to advance northward up the coast into the Pee
Dee region and eventually central to southern NC. A general
progressive motion is expected to these cells, but periods of
stalling will be possible with the rainfall axis which could
support locally higher rainfall rates, with 2-3 in/hr not out of
the question. Some overlap of these rain bands with an axis of 2-5
inches which impacted locations between CHS and MYR toward FLO.
Additional rainfall totals of 2-4 inches will be possible through 16Z.