066
FXUS01 KWBC 202001
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EST TUE FEB 20 2024
VALID 00Z WED FEB 21 2024 - 00Z FRI FEB 23 2024
...HEAVY RAIN AND HEAVY MOUNTAIN SNOW IN CALIFORNIA CONTINUE
THROUGH TOMORROW BEFORE SUBSIDING...
...WARMING TREND EXPECTED TO EXPAND FROM THE GREAT PLAINS INTO THE
MIDWEST THROUGH MIDWEEK...
...CRITICAL FIRE WEATHER DAY OVER PORTIONS OF THE SOUTHERN PLAINS
ON WEDNESDAY...
THE MAIN AREA OF UNSETTLED WEATHER THROUGH THE NEXT 24 HOURS
REMAINS OVER CALIFORNIA AS SHOWERS AND THUNDERSTORMS STREAM INLAND
ASSOCIATED WITH A DEEP UPPER-TROUGH AND ATMOSPHERIC RIVER.
SOUTHERN CALIFORNIA IS ONCE AGAIN "UNDER THE GUN" FOR NUMEROUS
INSTANCES OF FLASH FLOODING AS THE MAIN BAND OF ATMOSPHERIC RIVER
RAINFALL FOCUSES THROUGH THE OVERNIGHT HOURS THERE. GIVEN THE
COMBINATION OF SATURATED SOILS FROM PREVIOUS RAINFALL AND PERIODS
OF HIGH RAINFALL RATES APPROACHING 1"/HOUR, A MODERATE RISK OF
EXCESSIVE RAINFALL IS IN EFFECT FOR LOS ANGELES AND NORTHERN SAN
DIEGO COUNTIES THROUGH TOMORROW MORNING. OUTSIDE OF THESE AREAS, A
BROADER SLIGHT RISK AREA (LEVEL 2/4) EXTENDS FROM HUMBOLDT COUNTY
DOWN TO SAN DIEGO, AS WELL AS THE SACRAMENTO VALLEY AND ADJACENT
UPSLOPE AREAS OF THE SIERRA WHERE SCATTERED FLASH FLOODING IS
POSSIBLE. IN THE MOUNTAINS, AN ADDITIONAL 6-12 INCHES OF SNOWFALL
ARE EXPECTED FOR THE SIERRA, WHILE 12-18 INCHES ARE LIKELY OVER
THE SHASTA SISKIYOUS TODAY. EAST OF THE SIERRA, THE INFLUX OF
EASTERN PACIFIC MOISTURE COMBINED WITH FALLING SNOW LEVELS WILL
SUPPORT MODERATE TO HEAVY SNOW OVER THE INTERMOUNTAIN WEST WHERE
GENERALLY BETWEEN 6-12 INCHES OF SNOW CAN BE EXPECTED. THIS
SNOWFALL IS LIKELY TO CONTINUE INTO WEDNESDAY AND EXPAND IN
COVERAGE INTO THE CENTRAL ROCKIES.
EAST OF THE CONTINENTAL DIVIDE, WIDESPREAD UNSEASONABLE WARMTH
WILL PREVAIL THROUGH THE WORK WEEK AS ALL OF THE COLD POLAR AIR
REMAINS CONFINED OVER CANADA. THIS WARM WEATHER COMBINED WITH DRY,
WINDY CONDITIONS BEHIND A COLD FRONT AND DRYLINE SUPPORTS A
CRITICAL (LEVEL 2/3) FIRE WEATHER THREAT OVER PORTIONS OF THE
SOUTHERN PLAINS TOMORROW ACCORDING TO THE STORM PREDICTION CENTER.
BY THURSDAY, A DEVELOPING WAVE OF LOW-PRESSURE ALONG A COLD FRONT
WILL YIELD WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE OHIO
VALLEY, WHICH COULD LEAD TO ISOLATED INSTANCES OF FLASH FLOODING.
ASHERMAN/KEBEDE
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