984
FXUS01 KWBC 240659
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST TUE DEC 24 2024
VALID 12Z TUE DEC 24 2024 - 12Z THU DEC 26 2024
...HEAVY RAIN AND MOUNTAIN SNOW RETURNS TO THE WEST COAST REGION
WEDNESDAY NIGHT...
...SHOWERS AND THUNDERSTORMS DEVELOPING OVER PORTIONS OF THE
SOUTH-CENTRAL STATES...
...RELATIVELY MILD CONDITIONS ACROSS THE MAJORITY OF THE COUNTRY
LEADING UP TO CHRISTMAS...
AN ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE ACROSS THE WEST
COAST REGION AS AN ENERGETIC STORM TRACK ACROSS THE EASTERN
PACIFIC BRINGS IN MULTIPLE ROUNDS OF PRECIPITATION. THE NEXT IN A
SERIES OF ATMOSPHERIC RIVER EVENTS IS ARRIVING ACROSS NORTHERN
CALIFORNIA AND WESTERN OREGON LATE TONIGHT AND CONTINUING INTO
TUESDAY AFTERNOON. ALTHOUGH THE STORM SYSTEM WILL BE PROGRESSIVE
OVERALL, THERE WILL BE A DEEP SURGE OF MOISTURE AHEAD OF THE COLD
FRONT THAT WILL INTERSECT THE COASTAL TERRAIN AND THE WESTERN
SLOPES OF THE NORTHERN SIERRA NEVADA. RAINFALL TOTALS ON THE
ORDER OF 2-4 INCHES, AND LOCALLY HIGHER, ARE LIKELY ACROSS THIS
REGION THROUGH TUESDAY EVENING. SNOW LEVELS WILL BE INITIALLY
HIGH, BUT SHOULD FALL SOME ONCE THE FRONT PASSES. THE HEAVIEST
SNOW FROM THIS EVENT SHOULD AFFECT THE HIGHEST TERRAIN OF THE
CENTRAL SIERRA NEVADA, WITH UP TO A FOOT OF ACCUMULATION POSSIBLE,
AFFECTING TRAVEL THROUGH THE MOUNTAIN PASSES. WINTER WEATHER
ADVISORIES AND WINTER STORM WARNINGS ARE CURRENTLY IN EFFECT FOR
THIS EVENT. AFTER A BRIEF BREAK ON CHRISTMAS DAY, THE NEXT ROUND
OF MOISTURE MOVES IN TOWARDS THE WEST COAST AND BRINGS ANOTHER
SUBSTANTIAL ROUND OF RAIN AND MOUNTAIN SNOW, ALONG WITH WINDY
CONDITIONS AS THE PRESSURE GRADIENT TIGHTENS IN RESPONSE TO A VERY
INTENSE SURFACE LOW OFF THE COAST OF BRITISH COLUMBIA.
A RELATIVELY WEAK LOW PRESSURE SYSTEM CROSSING THE NORTHEAST U.S.
REGION ON TUESDAY WILL PRODUCE LIGHT TO OCCASIONALLY MODERATE SNOW
FROM THE CENTRAL APPALACHIANS TO NEW ENGLAND, INCREASING THE ODDS
OF A WHITE CHRISTMAS ACROSS THIS REGION, ESPECIALLY WHEN COMBINED
WITH EXISTING SNOW COVER FROM RECENT SNOWFALL. THIS SYSTEM
QUICKLY EXITS OFFSHORE BY TUESDAY EVENING. FARTHER TO THE SOUTH
ACROSS TEXAS, A SEPARATE SURFACE LOW DEVELOPS, AND INCREASING
SOUTHERLY FLOW FROM THE WESTERN GULF OF MEXICO AHEAD OF THAT
SYSTEM WILL FUEL THE DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS
AND SOME THUNDERSTORMS, MAINLY FROM EASTERN TEXAS NORTHWARD ACROSS
MUCH OF ARKANSAS AND INTO SOUTHERN MISSOURI THROUGH CHRISTMAS
MORNING. SOME LOCATIONS MAY GET OVER AN INCH OF RAINFALL WITH
THIS EVENT, AND THUS A MARGINAL RISK OF EXCESSIVE RAINFALL IS
VALID FOR THESE AREAS.
MUCH OF THE EAST COAST REGION WILL HAVE A MODERATION TREND IN THE
COLD TEMPERATURES GOING INTO CHRISTMAS EVE, AS THE ARCTIC SURFACE
HIGH MOVES OFFSHORE AND MILDER AIR FROM THE OHIO VALLEY ADVECTS
EASTWARD ACROSS THE REGION. THE REMAINDER OF THE COUNTRY SHOULD
ENJOY GENERALLY ABOVE AVERAGE TEMPERATURES BY LATE DECEMBER
STANDARDS, PARTICULARLY ACROSS THE CENTRAL AND SOUTHERN PLAINS
WHERE DAYTIME HIGHS COULD BE 15-20 DEGREES ABOVE AVERAGE. THIS
WOULD EQUATE TO HIGHS WELL INTO THE 60S AND 70S FOR MUCH OF TEXAS.
HAMRICK
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