854
FXUS01 KWBC 301958
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 PM EDT TUE MAY 30 2023
VALID 00Z WED MAY 31 2023 - 00Z FRI JUN 02 2023
...WIDESPREAD SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE ACROSS
LARGE PORTIONS OF THE CENTRAL U.S., THE NORTHERN ROCKIES AND
NORTHERN GREAT BASIN...
...SCATTERED SHOWERS SPREAD INTO THE SOUTHERN MID-ATLANTIC TODAY,
WITH AN INCREASING CHANCE OF THUNDERSTORMS ACROSS SOUTHERN FLORIDA
ON WEDNESDAY...
...MUCH ABOVE AVERAGE TEMPERATURES EXPECTED ALONG THE NORTHERN
TIER OF THE NATION, WHILE COOLER THAN NORMAL CONDITIONS ACCOMPANY
THE SHOWERS ACROSS THE SOUTHEAST...
THE UPPER-LEVEL PATTERN OVER THE CONTIGUOUS U.S. REMAINS BLOCKED
GOING INTO THE NEXT FEW DAYS, INDICATING THAT THERE WILL NOT BE
MANY LARGE-SCALE CHANGES IN THE SHORT-TERM FORECAST PERIOD. THERE
IS A BROAD TROUGH OVER THE WESTERN HALF OF THE COUNTRY, A
POSITIVELY-TILTED TROUGH OVER THE SOUTHEAST U.S. AND INTO THE
WESTERN ATLANTIC OCEAN, AND A CLOSED UPPER-LEVEL HIGH OVER THE
CENTRAL AND NORTHEASTERN U.S.
WIDESPREAD SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
IMPACT MUCH OF THE WEST, PARTICULARLY OVER AREAS EXTENDING FROM
NORTHERN CALIFORNIA INTO THE YELLOWSTONE REGION, AS WELL AS INTO
PORTIONS OF THE CENTRAL PLAINS. SHOWERS AND THUNDERSTORMS WILL BE
MORE NUMEROUS DURING THE DAYTIME, WHERE DAYTIME HEATING AND
TERRAIN-INDUCED LIFT MAY INITIATE SHOWERS AND THUNDERSTORMS. HEAVY
RAINFALL RATES OF 0.5-1"/HR ARE POSSIBLE ACROSS A BROAD PORTION OF
THE WEST, WHICH MAY RESULT IN LOCALIZED FLASH FLOODING, ESPECIALLY
IN URBAN/POOR DRAINAGE AREAS. THEREFORE, A MARGINAL RISK (LEVEL
1/4) OF EXCESSIVE RAINFALL IS IN EFFECT FOR PORTIONS OF THE
INTERMOUNTAIN WEST/NORTHERN HIGH PLAINS. BY WEDNESDAY INTO
THURSDAY, A MID-UPPER LOW OVER THE FOUR CORNERS REGION WILL EJECT
TOWARD THE NORTHERN HIGH PLAINS AND INCREASE CHANCES FOR HEAVY
PRECIPITATION OVER NORTHERN WYOMING AND MONTANA. THEREFORE, A
SLIGHT RISK (LEVEL 2/4) FOR EXCESSIVE RAINFALL IS IN EFFECT FOR
PORTIONS OF MONTANA ON THURSDAY. TEMPERATURES WILL GENERALLY COOL
ACROSS THE REGION THROUGH THE MIDDLE OF THIS WEEK, WITH MOSTLY
SEASONAL HIGH TEMPERATURES EXPECTED ACROSS THE REGION BY MIDWEEK.
OVER THE HIGH PLAINS, SHORTWAVES EMBEDDED IN THE BROAD TROUGH OVER
THE WEST MAY INITIATE SHOWERS AND THUNDERSTORMS, WITH LOCALLY
HEAVY AND SEVERE IMPACTS POSSIBLE. IN ADDITION, SUSTAINED MOIST,
SOUTHERLY FLOW FROM THE GULF OF MEXICO MAY ACT TO ENHANCE RAINFALL
RATES/TOTALS AND INDUCE SEVERE WEATHER. THIS SETUP HAS THE
POTENTIAL TO PRODUCE ISOLATED HEAVY RAINFALL ACCUMULATIONS OF 1-2"
(LOCALLY HIGHER) ACROSS PORTIONS OF THE CENTRAL/SOUTHERN PLAINS. A
MARGINAL RISK OF EXCESSIVE RAINFALL IS IN EFFECT FOR THIS REGION
FOR THE AFOREMENTIONED REASONS. ADDITIONALLY, THE STORM PREDICTION
CENTER HAS ISSUED AN ENHANCED RISK (LEVEL 3/5) OF SEVERE WEATHER
FOR MUCH OF FAR-EASTERN COLORADO, FAR WESTERN KANSAS, AS WELL AS
THE ADJACENT SURROUNDING AREAS. THE PRIMARY SEVERE HAZARD WILL BE
HIGH WIND GUSTS. GIVEN THE BLOCKED UPPER-LEVEL PATTERN, ISOLATED
REGIONS OF HEAVY RAINFALL AND SEVERE WEATHER ARE POSSIBLE OVER THE
WESTERN HIGH PLAINS THROUGH THE REST OF THE FORECAST PERIOD.
ACROSS THE MID-ATLANTIC, A WEAKENING UPPER LOW WILL SLOWLY DRIFT
INTO THE ATLANTIC AS A BACK-DOOR COLD FRONT PUSHES COLDER AIR FROM
NEW ENGLAND DOWN THE EAST COAST AND APPALACHIANS. LIGHT SCATTERED
SHOWERS AND THUNDERSTORMS WILL SLOWLY DISSIPATE THROUGHOUT TUESDAY
EVENING, WITH CONDITIONS BECOMING COOLER AND DRIER OVER IN THE
SHORT-TERM FORECAST. TO THE SOUTH, AN UPPER-LEVEL TROUGH WILL
SETTLE OVER THE CENTRAL GULF OF MEXICO, WHICH MAY SPAWN A NEW
LOW-PRESSURE SYSTEM AT THE SURFACE. THIS SYSTEM IS BEING CURRENTLY
BEING MONITORED BY THE NATIONAL HURRICANE CENTER, WITH A 10%
CHANCE OF FORMATION THROUGH THE NEXT 48 HOURS. THE EXACT TRACK OF
THIS SYSTEM REMAINS UNCERTAIN, BUT CURRENT FORECASTS KEEP IT
RELATIVELY STATIONARY OVER THE CENTRAL GULF IN THE NEAR-TERM.
SCATTERED SHOWERS AND THUNDERSTORMS, WITH LOCALLY HEAVY AMOUNTS
POSSIBLE, ARE EXPECTED TO INITIATE OVER THE FLORIDA PENINSULA
STARTING ON WEDNESDAY WITH HIGH MOISTURE CONTENT DRAPED ACROSS THE
REGION.
A CLOSED UPPER HIGH WILL REMAIN RELATIVELY STATIONARY ACROSS THE
NORTHEASTERN PORTION OF THE NATION FROM THE GREAT LAKES INTO NEW
ENGLAND. DRY CONDITIONS AND WELL ABOVE AVERAGE TEMPERATURES WILL
ACCOMPANY THIS UPPER HIGH WITH HIGH TEMPERATURES 15 TO 20 DEGREES
ABOVE AVERAGE ACROSS MUCH OF THE NORTHERN TIER FROM THE NORTHERN
PLAINS, THROUGH THE UPPER GREAT LAKES, NORTHERN NEW YORK STATE
INTO NORTHERN NEW ENGLAND. SOME HIGH TEMPERATURE RECORDS MAY BE
BROKEN THIS WEEK OVER PORTIONS OF THE GREAT LAKES AND NORTHEAST,
PARTICULARLY ON THURSDAY AFTERNOON. IN CONTRAST, COOLER THAN
AVERAGE TEMPERATURES OVER THE NEXT FEW DAYS WILL BE ASSOCIATED
WITH THE SHOWERY PATTERN ACROSS THE SOUTHEASTERN U.S. AND ALONG
THE WEST COAST INTO THE DESERT SOUTHWEST.
GENZ/KONG
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