BBS: TELESC.NET.BR
Assunto: MESO: Nws Weather Prediction Center College Park Md
De: COD Weather Processor
Data: Wed, 27 May 2026 06:57:40 +0000
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AWUS01 KWNH 270657
FFGMPD
PAZ000-MDZ000-WVZ000-OHZ000-INZ000-271245-
Mesoscale Precipitation Discussion 0255
NWS Weather Prediction Center College Park MD
256 AM EDT Wed May 27 2026
Areas affected...Eastern IND...Central OH...Southeast PA...Western
MD... Northern WV...
Concerning...Heavy rainfall...Flash flooding possible
Valid 270700Z - 271245Z
SUMMARY...Scattered warm-advection showers will have high rainfall
efficiency with rates up to 1-1.5"/hr will eventually stall and
align favorably for repeating along the mid-level front. Streaks
of 1-2" over recently saturated soils pose widely scatted
incidents of possible flash flooding.
DISCUSSION...GOES-E WV suite depict the elongating/shearing older
closed low near St. Louis Missouri with a deep laminar elongated,
deformation/shear axis across central IL/IND/OH and PA. South of
which, broad south to south-southwesterly 15-20kt low-level jet is
lifting the surface front more in line with the aforementioned
axis. Deep layer moisture remains pooled along the steepening
frontal zone with values of 1.5-1.75" (slightly higher further
east). Further west, a bit of drier air aloft and therefore
slightly steepened lapse rates is support some 500-1000 J/kg of
MUCAPE, though this becomes 250-500 J/kg further east through the
central Appalachians. As such, solid moisture flux convergence
along the vertically steepening isentropic boundary is starting to
break out a few narrow currently scattered showers from central IL
through eastern OH. WV suite also denotes core of upper-level jet
streak over central OH before turning eastward over PA/NY,
providing some modest divergence aloft, again slightly east.
All elements considered the updrafts will support efficient
rainfall production given the moist environment but due to the
likely narrow updrafts due to weak instability, rates of .75-1"/hr
will be more common, though ideal storm-scale interactions may
allow for up to 1.5" locally and for short time periods. Ascent
will continue through the late overnight period/early morning with
increasing convective cells along the boundary. Deep layer
steering quickly veers along the shear axis to support west to
east propagation and potential for these showers to repeat.
As such, localized streaks of 1-2" are possible though the morning
with increasing potential from central OH to the spine of the
Appalachians. Recent prolonged moderate to heavy rainfall has
soaked the upper-soil environment particularly over E OH into the
central Appalachians, where hourly FFG value are barely over 1"
and 3hr values are mostly less than 1.5". Further west into
central IL/IND, FFG values rise and are likely to be just out of
reach with only exception for a very isolated stationary cell or
two. As such, localized incidents of flash flooding will be
considered possible from Eastern IND into SE PA/W MD/E WV.=20
Note: There are some hints of prolonged training events within the
Hi-Res CAM suite with higher localized totals of 2.5"+. While
confidence is not high, these unidirectional flow regimes with
trapped deep layer moisture, vorticity and prolonged training
potential can be particularly dangerous especially in the complex
terrain of E OH, N WV and SE PA/W MD.
Gallina
...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6z5JaBq1DiZS0Bi0r2lQJtOQQgR7npXAVFCKxVzfESqNvEuIl93hMzYYPQHF_f7DXHt7=
O_Z33TWe2grjJU-ruADxGGo$ for graphic product...
ATTN...WFO...CLE...CTP...ILN...IND...LWX...PBZ...RLX...
ATTN...RFC...RHA...TIR...NWC...
LAT...LON 40378148 40307964 40047857 39757831 39227854=20
38667926 38808013 39188204 39308360 39238533=20
39658569 39998566 40318460=20
=3D =3D =3D
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