481
ACUS11 KWNS 180543
SWOMCD
SPC MCD 180542
IAZ000-180815-
MESOSCALE DISCUSSION 0465
NWS STORM PREDICTION CENTER NORMAN OK
1242 AM CDT FRI APR 18 2025
AREAS AFFECTED...NORTHERN IOWA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 180542Z - 180815Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A THREAT FOR MARGINALLY SEVERE HAIL IS EXPECTED OVER THE
NEXT FEW HOURS ACROSS NORTHERN IOWA. WEATHER WATCH ISSUANCE APPEARS
UNLIKELY.
DISCUSSION...THE LATEST WATER VAPOR IMAGERY SHOWS WEST TO SOUTHWEST
FLOW OVER THE UPPER MIDWEST, WITH SOME ANTICYCLONIC CURVATURE. IN
SPITE OF SOME RIDGING, THE RAP SUGGESTS A MINOR SHORTWAVE TROUGH IS
MOVING THROUGH IOWA. AT THE SURFACE, A FRONT EXTENDS NORTHEASTWARD
ACROSS CENTRAL IOWA. SCATTERED THUNDERSTORMS ARE ONGOING TO THE
NORTHWEST OF THE FRONT IN THE VICINITY OF SIOUX CITY, IOWA. RAP
FORECAST SOUNDINGS TO THE NORTH OF FRONT OVER MUCH OF NORTHERN IOWA
HAVE AN INVERSION UP TO NEAR 800 MB. MUCAPE IS UP TO 1500 J/KG WITH
EFFECTIVE SHEAR IN THE 50 TO 60 KNOTS RANGE. 700-500 MB LAPSE RATES
ARE NEAR 8 C/KM. AS WARM ADVECTION CONTINUES OVERNIGHT, THIS
ENVIRONMENT SHOULD SUPPORT ELEVATED SUPERCELL DEVELOPMENT.
SUPERCELLS MAY BE ABLE TO PRODUCE ISOLATED LARGE HAIL, BUT ANY
THREAT IS EXPECTED TO REMAIN ISOLATED.
..BROYLES/GLEASON.. 04/18/2025
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...DVN...ARX...DMX...FSD...OAX...
LAT...LON 42289246 42249433 42179531 42229595 42539635 42729641
42889639 43239600 43429526 43449260 43179150 42459149
42289246
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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