719
ACUS03 KWNS 060731
SWODY3
SPC AC 060730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT THU MAY 06 2021
VALID 081200Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SATURDAY AFTERNOON
INTO SATURDAY NIGHT ACROSS PARTS OF CENTRAL AND EASTERN KANSAS INTO
NORTHERN OKLAHOMA...
..SUMMARY
STRONG TO SEVERE THUNDERSTORM DEVELOPMENT IS POSSIBLE ACROSS PARTS
OF THE CENTRAL AND SOUTHERN GREAT PLAINS ON SATURDAY. SOME OF THESE
STORMS WILL BE ACCOMPANIED BY THE RISK FOR LARGE HAIL, STRONG WIND
GUSTS, AND PERHAPS A COUPLE OF TORNADOES.
..SYNOPSIS
MODELS INDICATE THAT BLOCKING WILL REMAIN PROMINENT WITHIN THE
LARGE-SCALE PATTERN THROUGH THIS PERIOD AND BEYOND, AND THERE IS
CONSIDERABLE SPREAD EVIDENT AMONG THE VARIOUS MODELS CONCERNING THIS
EVOLUTION, PARTICULARLY WITH REGARD TO THE SMALLER-SCALE
DEVELOPMENTS. IN GENERAL, IT APPEARS THAT ONE INITIAL HIGH CENTER,
OVER THE LABRADOR SEA VICINITY, WILL BEGIN TO SHIFT/REDEVELOP
EASTWARD TOWARD SOUTHERN GREENLAND, AS STRONG LOWER/MID TROPOSPHERIC
CYCLOGENESIS PROCEEDS EAST OF THE NORTH ATLANTIC COAST INTO THE
CANADIAN MARITIMES.
WHILE A DEVELOPING MID-LEVEL LOW BECOMES INCREASINGLY PROMINENT NEAR
THE CANADIAN MARITIMES, AN INITIALLY MORE PROMINENT MID-LEVEL LOW
IS FORECAST TO LINGER SOUTHWEST OF JAMES BAY. UPSTREAM, MODELS
INDICATE ANOTHER MID-LEVEL HIGH WILL EVOLVE OVER NORTHERN
SASKATCHEWAN, WHILE LARGE-SCALE MID-LEVEL RIDGING ALSO AMPLIFIES
ACROSS THE EASTERN PACIFIC. A STRONG JET ROUNDING THE CREST OF THE
PACIFIC RIDGING MAY CONTRIBUTE TO DIGGING MID/UPPER TROUGHING INLAND
OF THE PACIFIC COAST, WITH BROADLY CYCLONIC DOWNSTREAM ALSO
DEVELOPING EAST OF THE ROCKIES, INTO THE GREAT PLAINS BY LATE
SATURDAY NIGHT.
THE MOST PROMINENT SHORT WAVE PERTURBATION WITHIN THIS CYCLONIC
FLOW, WHICH MAY EVOLVE INTO ANOTHER MID-LEVEL CLOSED LOW, APPEARS
LIKELY TO SHIFT EAST OF THE NORTHERN U.S. INTERMOUNTAIN REGION,
ACROSS THE NORTHERN ROCKIES. HOWEVER, ONE OR TWO SIGNIFICANT
IMPULSES ARE FORECAST TO EMERGE FROM THE SOUTHWEST, AND CONTRIBUTE
TO THE SUPPRESSION OF MID-LEVEL RIDGING INITIALLY ACROSS THE
CENTRAL/SOUTHERN GREAT PLAINS, BEFORE BEGINNING TO TRANSLATE ACROSS
AND EAST OF THE MIDDLE/LOWER MISSISSIPPI VALLEY.
COINCIDING WITH THESE DEVELOPMENTS, MODELS CONTINUE TO INDICATE THAT
MODEST SURFACE CYCLOGENESIS WILL TAKE PLACE THROUGH THIS PERIOD,
FROM THE LEE OF THE COLORADO FRONT RANGE INTO THE CENTRAL GREAT
PLAINS. IT APPEARS THAT ASSOCIATED STRENGTHENING OF SOUTHERLY
LOW-LEVEL FLOW ACROSS THE SOUTHERN INTO CENTRAL GREAT PLAINS WILL
SUPPORT A MORE RAPID RETURN OF MOISTURE EMANATING FROM A MOIST
WESTERN GULF OF MEXICO BOUNDARY, BENEATH STEEP-LAPSE RATES
ASSOCIATED WITH WARM ELEVATED MIXED-LAYER AIR.
..PARTS OF CENTRAL AND SOUTHERN GREAT PLAINS
MODELS SUGGEST THAT THE STEEPENING LAPSE RATES AND LOW-LEVEL
MOISTURE RETURN WILL SUPPORT THE DEVELOPMENT OF AT LEAST MODERATELY
LARGE CAPE ON THE ORDER OF 1000-2000 J/KG, WITH HIGHEST VALUES
FOCUSED ALONG AND EAST OF A DEVELOPING DRYLINE ACROSS THE TEXAS BIG
COUNTRY AND WESTERN OKLAHOMA INTO A DEVELOPING WARM FRONTAL ZONE
ACROSS CENTRAL KANSAS. ALTHOUGH THE DETAILS OF THE POTENTIAL
CONVECTIVE EVOLUTION REMAIN UNCLEAR, THE DRYLINE, THE WARM FRONTAL
ZONE, AND THE COLD FRONT DEVELOPING IN THE WAKE OF THE EMERGING
CYCLONE MAY ALL BECOME THE FOCUS FOR STRONG TO SEVERE STORM
DEVELOPMENT LATE SATURDAY AFTERNOON INTO SATURDAY NIGHT, IN THE
PRESENCE OF STRENGTHENING LOW-LEVEL AND DEEP-LAYER SHEAR. HIGHEST
PROBABILITIES SEEM LIKELY TO BECOME FOCUSED NEAR THE WARM
FRONT/DRYLINE INTERSECTION, EASTWARD ALONG OR JUST SOUTH OF THE WARM
FRONT, WHERE SUPERCELLS MAY INITIATE, BEFORE CONVECTION POSSIBLY
GROWS UPSCALE INTO AN ORGANIZING CLUSTER. BASED ON TRENDS IN MODEL
OUTPUT, PARTICULARLY CONCERNING POTENTIAL DESTABILIZATION, IT IS
POSSIBLE THAT MARGINAL AND SLIGHT RISK CATEGORIES MIGHT NEED TO BE
BUMPED UP A CATEGORY IN LATER OUTLOOKS FOR THIS PERIOD.
..KERR.. 05/06/2021
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