MD 1845 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PARTS OF WESTERN MT…FAR EASTERN ID…AND NORTHWEST WY
Mesoscale Discussion 1845
NWS Storm Prediction Center Norman OK
0106 PM CDT Thu Sep 29 2022
Areas affected...Parts of western MT...far eastern ID...and
northwest WY
Concerning...Severe potential...Watch unlikely
Valid 291806Z - 292030Z
Probability of Watch Issuance...5 percent
SUMMARY...The risk of isolated strong to severe gusts and marginal
hail should gradually increase in the next few hours. Overall, the
severe risk is expected to remain marginal and localized.
DISCUSSION...Latest water vapor imagery shows a closed midlevel low
tracking slowly eastward across the Northwest, preceded by
increasing DCVA/large-scale ascent characterized by modest midlevel
height-falls over the last 12 hours. As the increasing ascent
continues overspreading a weak north/south-oriented baroclinic zone
from western MT into eastern ID, convection will gradually increase
in coverage given continued destabilization/steepening low/midlevel
lapse rates this afternoon.
Regional VWP data depicts 30-40-kt south-southwesterly midlevel flow
preceding the closed midlevel low, which should favor modestly
elongated/straight midlevel hodographs (35-45 kt of effective shear)
across western MT southward into eastern ID and northwest WY. While
buoyancy will be somewhat marginal (generally driven by steep
low/midlevel lapse rates), the combination of strengthening forcing
for ascent and sufficient deep-layer shear could favor loosely
organized convection as it spreads northeastward this afternoon.
Marginal hail will be possible with any initial cellular
development, though strong to severe gusts should be the main hazard
as convection grows upscale into clusters or bands owing to the
strengthening large-scale ascent amid straight hodographs. Overall,
the severe threat is expected to remain marginal and localized.
..Weinman/Thompson.. 09/29/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BYZ...RIW...TFX...PIH...MSO...
LAT...LON 44021131 44781154 45391201 46061243 46961311 47541367
48081387 48461357 48671302 48661173 48261105 47421037
46700996 45770971 44940953 43670964 43450998 43391080
43511120 44021131
