638
ACUS48 KWNS 160852
SWOD48
SPC AC 160850
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0350 AM CDT WED OCT 16 2019
VALID 191200Z - 241200Z
..DISCUSSION
DAY 4/SATURDAY: A WEAK UPPER SHORTWAVE TROUGH OVER EASTERN PORTIONS
OF THE PLAINS ON SATURDAY WILL QUICKLY LIFT NORTHEAST. AT THE
SURFACE, A WEAK COLD FRONT WILL SWEEP ACROSS THE UPPER MIDWEST/GREAT
LAKES WHILE STALLING OVER THE SOUTHERN PLAINS. MEANWHILE, GUIDANCE
VARIES ON THE INTENSITY OF A TROPICAL DISTURBANCE AS IT TRACKS NEAR
THE NORTHERN GULF COAST/SOUTHEASTERN U.S. ON SATURDAY. REFERENCE THE
TROPICAL WEATHER OUTLOOKS FROM THE NATIONAL HURRICANE CENTER FOR
MORE DETAILS ON THIS SYSTEM. HOW THIS LOW EVOLVES COULD INFLUENCE
SEVERE POTENTIAL ACROSS PARTS OF THE NORTHERN AND EASTERN GULF COAST
STATES INTO GA/SC ON SATURDAY, THOUGH SEVERE POTENTIAL APPEARS LOW
AT THIS TIME.
DAYS 5-7/SUNDAY-TUESDAY: SEVERE POTENTIAL IS EXPECTED TO INCREASE
ON SUNDAY AS A MORE INTENSE SHORTWAVE TROUGH EJECTS EASTWARD FROM
THE ROCKIES INTO THE PLAINS ON MONDAY. STRONG DEEP-LAYER
SOUTHWESTERLY FLOW WILL DEVELOP FROM THE SOUTHERN PLAINS TO THE
UPPER MIDWEST AS THE TROUGH DEEPENS OVER THE PLAINS. THE ECMWF AND
GFS ARE IN BETTER AGREEMENT OVER THE POSITION OF AN INTENSIFYING
SURFACE LOW COMPARED TO YESTERDAY, WITH THE LOW TRACKING ACROSS SD
THROUGH THE AFTERNOON BEFORE LIFTING NORTHEAST INTO MN OVERNIGHT. A
TRAILING COLD FRONT WILL PUSH EASTWARD ACROSS THE PLAINS, WITH SOME
TIMING DIFFERENCES AMONG VARIOUS GUIDANCE. DESPITE THIS, MODELS ARE
FAIRLY CONSISTENT IN MOIST RETURN FLOW BRINGING 60S SURFACE
DEWPOINTS NORTHWARD TO AT LEAST THE OZARK PLATEAU EASTWARD TOWARD
THE MID-SOUTH. AT LEAST A NARROW CORRIDOR OF SEVERE POTENTIAL IS
EXPECTED AHEAD OF THE COLD FRONT WHERE A FAVORABLE COMBINATION OF
INSTABILITY, STEEPENING MIDLEVEL LAPSE RATES, STRONG SHEAR AND UPPER
FORCING FOR ASCENT WILL ALIGN. OVER THE PAST FEW DAYS, THIS CORRIDOR
HAS BEEN MOST CONSISTENTLY INDICATED BY MEDIUM-RANGE GUIDANCE ACROSS
PARTS OF NORTH TX, EASTERN OK INTO ADJACENT PARTS OF KS/MO/AR.
CONFIDENCE HAS INCREASED SUFFICIENTLY TO INCLUDE 15% SEVERE
PROBABILITIES, THROUGH THIS AREA LIKELY WILL CHANGE SOME IN COME
DAYS AS FORECAST DETAILS HOPEFULLY BECOME MORE CLEAR.
A SEVERE THREAT COULD CONTINUE INTO MONDAY ACROSS PARTS OF THE
MID/LOWER MS VALLEY VICINITY EASTWARD TOWARD THE APPALACHIANS AS THE
COLD FRONT CONTINUES TO SURGE EASTWARD. A VERY MOIST AIRMASS WILL BE
IN PLACE DOWNSTREAM OF THE FRONT, BUT TIMING DIFFERENCES IN THE
EASTWARD PROGRESSION OF THE FRONT AMONG VARIOUS MODEL OUTPUT IS
LARGE, DECREASING FORECAST CONFIDENCE. THE COLD FRONT WILL CONTINUE
TO SHIFT EASTWARD ACROSS THE EASTERN U.S. AND IS EXPECTED TO MOVE
OFFSHORE MOST OF THE ATLANTIC COAST BY WEDNESDAY MORNING. DEPENDING
ON TIMING, SOME SEVERE THREAT IS POSSIBLE ACROSS PARTS OF THE
CAROLINAS AND MID-ATLANTIC, BUT AGAIN, CONFIDENCE REMAINS LOW.
BY DAY 8/WEDNESDAY, MEDIUM RANGE GUIDANCE VARIES GREATLY, BUT SEVERE
POTENTIAL SHOULD BE LOW WITH STRONG SURFACE HIGH PRESSURE
ENCOMPASSING MUCH OF THE PLAINS TO THE SOUTHEAST.
..LEITMAN.. 10/16/2019
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