SPC AC 180739
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0239 AM CDT SAT JUL 18 2015
VALID 201200Z - 211200Z
...THERE IS A SLGT RISK OF SVR TSTMS EXTENDING FROM SOUTHERN MN TO
EASTERN NEB AND SOUTHEAST TO THE LOWER OH VALLEY...
...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK AREA
FROM THE UPPER MS VALLEY TO THE CENTRAL PLAINS TO THE LOWER OH
VALLEY...
...SUMMARY...
ISOLATED TO SCATTERED STRONG TO SEVERE STORMS WILL BE POSSIBLE
MONDAY AFTERNOON AND EVENING FROM SOUTHERN MINNESOTA INTO EASTERN
NEBRASKA...WHILE STRONG TO SEVERE STORMS WILL BE POSSIBLE MONDAY
AFTERNOON THROUGH MONDAY NIGHT ACROSS THE LOWER MISSOURI VALLEY TO
THE LOWER OHIO VALLEY.
...SYNOPSIS...
MODELS TEND TO AGREE THAT TWO LOW-AMPLITUDE SHORTWAVE TROUGHS WILL
MOVE E/SEWD FROM THE CENTRAL AND NORTHERN PLAINS DURING DAY 3/MONDAY
AND POTENTIALLY PHASE ACROSS IA/NORTHERN MO AND IL BY EARLY MONDAY
EVENING. ALTHOUGH MODELS DIFFER SOMEWHAT IN THE TIMING OF THESE
MIDLEVEL FEATURES...THERE IS GENERAL AGREEMENT FOR AT LEAST WEAK
HEIGHT FALLS AND DPVA TO SPREAD ACROSS THE MID MO VALLEY TO MID MS
VALLEY THROUGH MONDAY AFTERNOON. TWO SURFACE BOUNDARIES WILL BE THE
PRIMARY FOCI FOR TSTM DEVELOPMENT THIS FORECAST PERIOD...WITH ONE
WIND SHIFT ADVANCING E/SEWD THROUGH THE UPPER MS AND MID MO
VALLEYS...WHILE THE SECOND QUASI-STATIONARY FRONT EXTENDS FROM THE
LOWER MO TO LOWER OH VALLEYS.
...SRN MN/ERN NEB/IA/ERN KS AND MO TO LOWER OH VALLEY...
STRONGER INSTABILITY IS EXPECTED TO RESIDE ALONG THE
QUASI-STATIONARY BOUNDARY ON MONDAY...THAN WITH POLEWARD EXTENT INTO
SOUTHERN MN WHERE SOME MOISTURE RETURN WILL CONTRIBUTE TO AT LEAST
MODERATE INSTABILITY FROM ERN NEB TO SRN MN. MODERATELY STRONG
WNWLY 500-MB WINDS ACCOMPANYING THE TRANSIENT MIDLEVEL IMPULSES WILL
SUPPORT STRENGTHENING EFFECTIVE BULK SHEAR FOR AN ORGANIZED
SEVERE-WEATHER THREAT.
TSTMS AND/OR CLUSTERS OF STORMS SHOULD BE ONGOING ACROSS PARTS OF
THE MID MO VALLEY...CENTRAL PLAINS AND LOWER MO VALLEY AT 12Z
MONDAY. NEW STORM DEVELOPMENT IS FORECAST ALONG THE SEWD-MOVING
FRONT INTO SRN MN TO ERN NEB MONDAY AFTERNOON...WHILE STORMS SHOULD
DEVELOP ALONG THE SRN PERIPHERY OF THE ONGOING
STORMS/CLOUDINESS/DIFFERENTIAL HEATING BOUNDARY IN NERN KS AND NRN
MO TO CENTRAL IL. AFOREMENTIONED INSTABILITY AND BULK SHEAR WILL
SUPPORT STRONG TO SEVERE STORMS.
STORMS SHOULD DIMINISH IN INTENSITY ACROSS THE UPPER MS VALLEY
MONDAY NIGHT DUE TO WEAKENING INSTABILITY....WHILE FARTHER TO THE
SOUTH...A FORWARD PROPAGATING MCS WILL BE POSSIBLE THROUGH THE MID
MS VALLEY TO LOWER OH VALLEY MONDAY NIGHT. THIS LATTER AREA COULD
HAVE A DAMAGING-WIND THREAT THROUGH MONDAY EVENING TO PART OF THE
OVERNIGHT PERIOD.
..PETERS.. 07/18/2015
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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