254
FXUS01 KWBC 251911
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EST WED DEC 25 2024
VALID 00Z THU DEC 26 2024 - 00Z SAT DEC 28 2024
...CONTINUED ROUNDS OF HEAVY RAIN AND MOUNTAIN SNOW FOR THE
PACIFIC NORTHWEST AND NORTHERN GREAT BASIN/ROCKIES...
...HEAVY RAIN AND SEVERE THUNDERSTORMS RETURN FOR EASTERN TEXAS
AND THE ARKLATEX ON THURSDAY...
...RELATIVELY MILD CONDITIONS ACROSS THE MAJORITY OF THE COUNTRY
THROUGH FRIDAY...
ACTIVE STORM TRACKS OVER THE NORTHWESTERN AS WELL AS SOUTH-CENTRAL
U.S. WILL KEEP UNSETTLED, IMPACTFUL WEATHER IN THE FORECAST OVER
THE NEXT COUPLE OF DAYS. IN THE NORTHWEST, MULTIPLE UPPER-LEVEL
WAVES/PACIFIC SYSTEMS WILL PASS OVER THE REGION BRINGING ROUNDS OF
MODERATE TO HEAVY LOWER ELEVATION/COASTAL RAIN, AN INLAND LOWER
ELEVATION RAIN/SNOW MIX, AND VERY HEAVY SNOW TO THE AREA MOUNTAIN
RANGES. ONE WAVE WILL PASS THROUGH THE PACIFIC NORTHWEST OVERNIGHT
CHRISTMAS AND INTO THE GREAT BASIN AND NORTHERN/CENTRAL ROCKIES
THURSDAY FOLLOWED QUICKLY BY A SECOND WAVE INTO THE PACIFIC
NORTHWEST BY FRIDAY MORNING. A FLOW OF PLENTIFUL MOISTURE FROM
THE PACIFIC/ATMOSPHERIC RIVER WILL LEAD TO SEVERAL INCHES OF RAIN
ALONG FAVORABLE UPSLOPE REGIONS OF THE COASTAL RANGES OF THE
PACIFIC NORTHWEST AND NORTHERN CALIFORNIA THROUGH FRIDAY WITH THE
POTENTIAL FOR SOME ISOLATED FLOODING. IN THE MOUNTAINS, STORM
TOTAL SNOWFALL OF AT LEAST 8-12" WILL BE COMMON, WITH LOCALLY
HIGHER AMOUNTS OF 2+ FEET POSSIBLE, ESPECIALLY FOR THE CASCADES
AND RANGES OF THE NORTHERN GREAT BASIN/ROCKIES. IN ADDITION,
STRONG, GUSTY WINDS ARE ALSO EXPECTED, AND WILL LEAD TO BLOWING
SNOW AND VERY DANGEROUS TRAVEL CONDITIONS IN THE MOUNTAINS.
SCATTERED SHOWERS AND THUNDERSTORMS WILL TAPER OFF THROUGH
CHRISTMAS EVENING FOR PORTIONS OF THE MIDDLE/LOWER MISSISSIPPI
VALLEY AND WESTERN GULF COAST ALONG A LINGERING FRONTAL BOUNDARY
FOLLOWING THE PASSAGE OF AN UPPER-LEVEL WAVE. ANOTHER WAVE
APPROACHING FROM THE WEST WILL LEAD TO LEE CYCLOGENESIS OVER THE
SOUTHERN PLAINS, HELPING TO REINFORCE THE FRONTAL BOUNDARY AND
ENCOURAGE VERY MOIST GULF RETURN FLOW NORTHWARD OVER EASTERN TEXAS
AND THE ARKLATEX OVERNIGHT. STORMS WILL INCREASE IN COVERAGE AND
INTENSITY THROUGH THURSDAY MORNING AND INTO THURSDAY AFTERNOON,
WITH SUFFICIENT CAPE AND WIND SHEAR FOR SOME SEVERE THUNDERSTORMS.
THE STORM PREDICTION CENTER HAS INCLUDED A SLIGHT RISK (LEVEL 2/5)
OF SEVERE WEATHER FOR THE THREAT OF LARGE HAIL, DAMAGING WINDS,
AND A FEW TORNADOES. IN ADDITION, THE PLENTIFUL MOISTURE AND
INTENSE STORMS WILL LEAD TO SOME LOCALLY HEAVY DOWNPOURS, WITH A
SLIGHT RISK OF EXCESSIVE RAINFALL (LEVEL 2/4) ALSO IN PLACE FOR
THE THREAT OF SOME SCATTERED INSTANCES OF FLASH FLOODING. THE
SYSTEM WILL CONTINUE NORTHEASTWARD FRIDAY, BRINGING AN EXPANDING
AREA OF SHOWERS AND THUNDERSTORMS ACROSS THE MISSISSIPPI AND LOWER
OHIO/TENNESSEE VALLEYS. A FEW ISOLATED SEVERE THUNDERSTORMS AND
INSTANCES OF FLASH FLOODING WILL REMAIN POSSIBLE, PARTICULARLY
FROM THE LOWER MISSISSIPPI VALLEY INTO THE LOWER TENNESSEE VALLEY.
ELSEWHERE, CONDITIONS WILL BE MOSTLY DRY EXCEPT FOR SOME ISOLATED
STORM CHANCES OVER FLORIDA. MOST OF THE COUNTRY WILL CONTINUE TO
SEE RELATIVELY MILD CONDITIONS TEMPERATURE-WISE THROUGH FRIDAY,
WITH THE GREATEST ANOMALIES OF 10-15 DEGREES FOCUSED OVER THE
PLAINS AND MISSISSIPPI VALLEY. FORECAST HIGHS GENERALLY RANGE FROM
THE 30S AND 40S FOR THE NORTHERN PLAINS AND GREAT LAKES; THE 40S
AND 50S FOR THE PACIFIC NORTHWEST, GREAT BASIN, NORTHERN/CENTRAL
ROCKIES, CENTRAL PLAINS, AND OHIO VALLEY; THE 50S AND 60S FOR
CALIFORNIA AND THE SOUTHERN ROCKIES/PLAINS; AND THE 60S AND 70S
FOR THE DESERT SOUTHWEST, TEXAS, THE LOWER MISSISSIPPI VALLEY, AND
FLORIDA. ONE REGION THAT WILL SEE SOME COOLER, MORE SEASONABLE
CONDITIONS THURSDAY WILL BE ALONG THE EAST COAST, WITH
TEMPERATURES IN THE 20S AND 30S IN NEW ENGLAND, THE 30S AND 40S IN
THE MID-ATLANTIC, AND 50S AND 60S INTO THE SOUTHEAST. TEMPERATURES
WILL BEGIN TO WARM ABOVE AVERAGE FOR MANY LOCATIONS HERE AS WELL
ON FRIDAY, WITH HIGHS GENERALLY 5-10 DEGREES WARMER.
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