119
ACUS48 KWNS 220846
SWOD48
SPC AC 220845
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0345 AM CDT THU AUG 22 2019
VALID 251200Z - 301200Z
..DISCUSSION
HEIGHT FALLS AND COOLING ALOFT WILL SPREAD SOUTHEASTWARD ACROSS THE
NORTHERN PLAINS ON SUNDAY/D4 AND TOWARD THE UPPER MS VALLEY BY
MONDAY/D5, WITH A COLD FRONT AFFECTING MUCH OF THE NORTHERN AND
CENTRAL PLAINS. DUE TO A RATHER LARGE SURFACE RIDGE OVER THE GREAT
LAKES AND NORTHEAST, THE MOIST PLUME PRECEDING THIS SYSTEM OVER THE
PLAINS WILL REMAIN NARROW, COMPRISED PRIMARILY OF MID 60S F
DEWPOINTS.
MODEL DIFFERENCES EXIST REGARDING THE POSITION (OR EXISTENCE) OF
UPPER DISTURBANCES PRECEDING THE MAIN SHORTWAVE TROUGH, SUCH AS THE
ECMWF DEPICTION OF A WEAK LOW OVER MO ON SUNDAY/D4. QUESTIONS
REGARDING INSTABILITY ALSO EXIST AS EARLY DAY STORMS ARE LIKELY OVER
PARTS OF THE NORTHERN PLAINS. AS SUCH, WILL DEFER SEVERE
PROBABILITIES TO LATER OUTLOOKS.
FOR THE D6-D8 PERIOD, A DEEP UPPER LOW WILL FORM OVER NORTHERN
ONTARIO WITH A BROAD REGION OF STRONG CYCLONIC FLOW ALOFT ENVELOPING
MUCH OF THE NORTHERN CONUS AND EASTERN CANADA. THIS WILL DRIVE A
COLD FRONT RATHER FAR SOUTH, PERHAPS TO THE NORTHERN GULF COAST BY
THURSDAY/D8. THIS WILL REDUCE THE POTENTIAL AREA OF THUNDERSTORMS
OVER MUCH OF THE PLAINS AND MS VALLEY.
..JEWELL.. 08/22/2019
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