314
ACUS48 KWNS 030851
SWOD48
SPC AC 030850
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0350 AM CDT WED JUN 03 2020
VALID 061200Z - 111200Z
..DISCUSSION
..DAY 4/SAT - EASTERN MT INTO WESTERN ND/SD
AN INTENSE SHORTWAVE IMPULSE EMBEDDED IN THE LARGER-SCALE WESTERN
UPPER TROUGH WILL EJECT NORTH/NORTHEAST FROM THE FOUR CORNERS
VICINITY TO THE NORTHERN HIGH PLAINS ON SATURDAY. IN RESPONSE, A
SURFACE LOW WILL DEEPEN OVER MT WITH A SURFACE TROUGH EXTENDING INTO
THE NORTHERN AND CENTRAL HIGH PLAINS. STRONG SOUTH/SOUTHEASTERLY LOW
LEVEL FLOW WILL TRANSPORT A SWATH OF RICHER BOUNDARY-LAYER MOISTURE
NORTHWEST ACROSS PARTS OF THE WESTERN DAKOTAS AND EASTERN/CENTRAL
MT. STRONG VERTICAL SHEAR WILL OVERLAP WITH STEEP MIDLEVEL LAPSE
RATES AND MODERATE INSTABILITY, AND STRONG TO SEVERE STORMS APPEAR
LIKELY FROM LATE AFTERNOON INTO THE OVERNIGHT HOURS. ALL SEVERE
HAZARDS APPEAR POSSIBLE WITH FORECAST SOUNDINGS SHOWING FAVORABLE
CONDITIONS FOR SUPERCELLS. AN INCREASING LOW LEVEL JET DURING THE
EVENING AND OVERNIGHT HOURS SUGGESTS POTENTIAL FOR UPSCALE GROWTH
DURING THE NIGHTTIME HOURS, WHICH WOULD INCREASE THE THREAT FOR
DAMAGING WINDS ACROSS PARTS OF NORTHEAST MT INTO THE WESTERN
DAKOTAS.
..DAY 4/SAT - MID-ATLANTIC VICINITY
AN UPPER TROUGH OVER ONTARIO AND QUEBEC WILL DEEPEN ACROSS THE
NORTHEAST AND MID-ATLANTIC VICINITY ON SATURDAY. A MOIST BOUNDARY
LAYER WILL BE IN PLACE AS A COLD FRONT DEVELOPS EASTWARD ACROSS THE
REGION DURING THE MORNING AND AFTERNOON. SOME STRONG TO SEVERE STORM
POTENTIAL APPEARS POSSIBLE, HOWEVER GUIDANCE VARIES WITH REGARDS TO
COVERAGE AND INTENSITY. UNCERTAINTY REMAINS TOO HIGH AT THIS TIME TO
INCLUDE 15+ PERCENT SEVERE PROBABILITIES, BUT THEY MAY BECOME
NECESSARY IN LATER OUTLOOKS.
..DAY 5/SUN - EASTERN DAKOTAS INTO WESTERN MN
MOISTURE WILL STREAM NORTHWARD ACROSS EASTERN PORTIONS OF THE
NORTHERN/CENTRAL PLAINS ON INCREASING SOUTHERLY LOW LEVEL FLOW AHEAD
OF A SURFACE LOW OVER THE NORTHERN HIGH PLAINS. SOME CONVECTION
COULD BE ONGOING DURING THE MORNING AS A CONTINUATION OF AN MCS FROM
THE DAY 4/SAT PERIOD OVER PARTS OF ND OR MN. NEVERTHELESS, A VERY
MOIST AND UNSTABLE ENVIRONMENT IS EXPECTED ACROSS THE EASTERN
DAKOTAS INTO WESTERN MN. AS A SURFACE LOW OVER EASTERN WY/MT SHIFTS
EASTWARD INTO THE WESTERN DAKOTAS, CONVECTION IS EXPECTED TO
REDEVELOP FROM LATE SUNDAY AFTERNOON INTO SUNDAY NIGHT. INITIAL
SUPERCELLS ARE POSSIBLE BEFORE ANOTHER ROUND OF UPSCALE GROWTH INTO
A BOWING MCS DEVELOPS OVERNIGHT INTO WESTERN MN. THE SOUTHWARD
EXTENT OF SEVERE POTENTIAL IS UNCERTAIN, BUT AN ISOLATED THREAT
COULD DEVELOP INTO PORTIONS OF NE ALONG A SURFACE TROUGH, AND SEVERE
PROBABILITIES MAY NEED TO BE ADDED TO THIS AREA IN SUBSEQUENT
OUTLOOKS.
..DAYS 5-8/SUN-WED - LOWER MS VALLEY TO UPPER GREAT LAKES
THERE IS QUITE A BIT OF UNCERTAINTY SURROUNDING THE EVOLUTION OF
WHAT IS CURRENTLY TROPICAL STORM CRISTOBAL. THE TS IS FORECAST BY
THE NATIONAL HURRICANE CENTER TO BE NEAR THE LA COAST SUNDAY NIGHT.
BEYOND THIS, THE REMAINS OF THE SYSTEM ARE EXPECTED TO EVENTUALLY
MERGE WITH THE WESTERN UPPER TROUGH AS IT EJECTS EASTWARD INTO THE
PLAINS EARLY NEXT WEEK, BREAKING DOWN THE UPPER RIDGE AND ALLOWING
THE TROPICAL SYSTEM TO DEVELOP NORTHWARD FROM THE GULF COAST. SOME
SEVERE THREAT WILL LIKELY ACCOMPANY THIS PROCESS FROM THE LOWER/MID
MS VALLEY TO THE UPPER GREAT LAKES EARLY TO MIDDLE OF NEXT WEEK.
HOWEVER, UNCERTAINTY IS TOO HIGH, PRECLUDING SEVERE PROBS AT THIS
TIME.
..LEITMAN.. 06/03/2020
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