528
FXUS01 KWBC 250801
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT WED OCT 25 2023
VALID 12Z WED OCT 25 2023 - 12Z FRI OCT 27 2023
..SIGNIFICANT EARLY SEASON WINTER STORM BRINGS HEAVY SNOWFALL TO
PORTIONS OF THE NORTHWEST, NORTHERN ROCKIES, AND NORTHERN PLAINS...
...WIDESPREAD HEAVY RAINFALL WITH SCATTERED TO WIDESPREAD
INSTANCES OF FLASH FLOODING POSSIBLE IN THE SOUTHERN PLAINS
WEDNESDAY...
...MUCH ABOVE AVERAGE TEMPERATURES FOR EASTERN AND CENTRAL
PORTIONS OF THE COUNTRY WHILE TEMPERATURES TURN FRIGID IN THE
NORTHERN ROCKIES AND PLAINS...
A SIGNIFICANT EARLY SEASON WINTER STORM HAS BEGUN ACROSS PORTIONS
OF THE NORTHWEST AND NORTHERN ROCKIES AND WILL SPREAD INTO THE
NORTHERN PLAINS WEDNESDAY. AN ENERGETIC, DEEP UPPER-LOW DROPPING
SOUTHWARD ACROSS THE REGION WILL BRING MULTIPLE WAVES OF HEAVY
SNOW NOT ONLY TO THE MOUNTAINS BUT ALSO TO THE LOWER ELEVATIONS
AND PLAINS AS HEIGHTS FALL AND COLDER AIR FLOWS SOUTHWARD BEHIND A
COLD FRONT. STORM TOTAL SNOWFALL OF 6-12", LOCALLY HIGHER, IS
EXPECTED FOR EASTERN MONTANA AND WESTERN NORTH DAKOTA. TOTALS OF
1-2 FEET WILL BE POSSIBLE IN THE HIGHER TERRAIN OF THE CASCADES
AND NORTHERN ROCKIES. SOME SNOW IS EXPECTED TO MIX IN WITH RAIN
FOR THE INTERIOR NORTHWEST AND NORTHERN GREAT BASIN, BUT
ACCUMULATIONS HERE SHOULD BE LIMITED. A FEW INCHES OF ACCUMULATING
SNOW ARE ALSO EXPECTED FURTHER EASTWARD INTO EASTERN NORTH DAKOTA
AND NORTHWESTERN MINNESOTA, LINGERING INTO FRIDAY JUST BEYOND THE
CURRENT FORECAST PERIOD. HEAVY SNOW RATES OF 1"/HR IN SOME OF THE
SNOW BANDS AND SNOW-COVERED, ICY ROADS WILL MAKE TRAVEL DIFFICULT.
TO THE EAST, SHOWERS AND THUNDERSTORMS WILL CONTINUE WITHIN A
BROAD WARM SECTOR FROM THE PLAINS INTO THE MIDWEST, WITH TWO
LOCALLY ENHANCED AREAS OF HEAVY RAINFALL EXPECTED. UPPER-LEVEL
ENERGY THAT HAS BEEN SLOWLY PROGRESSING THROUGH NORTHERN MEXICO
WILL FINALLY BEGIN TO EJECT NORTHEASTWARD OVER THE SOUTHERN PLAINS
ON WEDNESDAY, HELPING TO ENHANCE LIFT AND LEAD TO WIDESPREAD
THUNDERSTORM DEVELOPMENT/COVERAGE. ANOMALOUSLY MOIST AIR WELL
ESTABLISHED ACROSS THE REGION WILL HELP STORMS PRODUCE VERY HEAVY
DOWNPOURS, WITH MEAN SOUTHWESTERLY FLOW AND CONTINUAL STORM
DEVELOPMENT LEADING TO REPEATED ROUNDS OF RAIN, RAISING THE
POTENTIAL FOR TOTALS OF SEVERAL INCHES. A MODERATE RISK OF
EXCESSIVE RAINFALL (LEVEL 3/4) HAS BEEN INTRODUCED FROM THE TEXAS
BIG BEND REGION NORTHEASTWARD THROUGH NORTH TEXAS INTO
SOUTH-CENTRAL OKLAHOMA AS THIS THREAT FOR VERY HEAVY RAINFALL,
OVERLAPPING REGIONS THAT HAVE ALREADY SEEN RAINFALL OVER THE PAST
COUPLE OF DAYS, MAY LEAD TO SCATTERED TO WIDESPREAD INSTANCES OF
FLASH FLOODING. FURTHER TO THE NORTHEAST, A SECOND LOCAL MAXIMA OF
HEAVY RAINFALL CONTINUES FOR PORTIONS OF THE UPPER MISSISSIPPI
VALLEY/GREAT LAKES WHERE MOIST SOUTHERLY FLOW MEETS A
QUASI-STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE REGION.
ENERGETIC UPPER FLOW PARALLEL TO THE BOUNDARY WILL HELP TO PRODUCE
REPEATED ROUNDS OF HEAVY RAINFALL. A MARGINAL RISK OF EXCESSIVE
RAINFALL (LEVEL 1/4) IS IN PLACE FOR WEDNESDAY IN THE UPPER
MISSISSIPPI VALLEY, WITH A SLIGHT RISK (LEVEL 2/4) ON THURSDAY
EXTENDING INTO THE UPPER GREAT LAKES WHERE THIS RAINFALL WILL
OVERLAP WETTER ANTECEDENT CONDITIONS.
IN ADDITION TO THE HEAVY SNOW, A WINTER BLAST WILL FOLLOW THE COLD
FRONT PUSHING SOUTHWARD ACROSS THE NORTHERN ROCKIES AND PLAINS,
WITH THESE FRIGID TEMPERATURES EXPANDING SOUTHEASTWARD THROUGH THE
END OF THE WEEK. HIGHS ON WEDNESDAY WILL BE IN THE 20S FOR MOST OF
MONTANA, WITH SOME MORNING LOWS THURSDAY DROPPING INTO THE SINGLE
DIGITS. HIGHS WILL FALL INTO THE 20S AND 30S FOR PORTIONS OF
WYOMING AND THE WESTERN DAKOTAS/NEBRASKA BY THURSDAY. BLUSTERY
WINDS MAY LEAD TO SOME SUBZERO WIND CHILLS. HIGHS WILL ALSO BE
BELOW AVERAGE ACROSS THE NORTHWEST BUT NO WHERE NEAR AS FRIGID,
WITH 40S AND LOW 50S FORECAST. THESE COOLER TEMPERATURES WILL ALSO
EXPAND SOUTHWARD FOLLOWING THE COLD FRONT INTO NORTHERN CALIFORNIA
AND THE GREAT BASIN BY THURSDAY. THE SOUTHWEST WILL REMAIN NEAR
AVERAGE, WITH HIGHS IN THE 70S AND 80S. IN CONTRAST, TEMPERATURES
WILL BE RUNNING MUCH ABOVE AVERAGE THE NEXT COUPLE OF DAYS FOR
MOST OF THE CENTRAL AND EASTERN U.S. AHEAD OF THE COLD FRONT AS AN
UPPER-LEVEL RIDGE BUILDS TO THE EAST. FORECAST HIGHS WILL
GENERALLY RANGE FROM THE 60S TO LOW 70S FOR THE GREAT LAKES AND
INTERIOR NORTHEAST; THE 70S FROM THE CENTRAL PLAINS EASTWARD
THROUGH THE MIDDLE MISSISSIPPI VALLEY, OHIO VALLEY, AND INTO THE
NORTHEAST; AND THE 80S FOR THE SOUTHERN PLAINS AND SOUTHEAST.
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