456
FXUS01 KWBC 192001
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EST TUE DEC 19 2023
VALID 00Z WED DEC 20 2023 - 00Z FRI DEC 22 2023
...A SLOW-MOVING LOW PRESSURE SYSTEM IS FORECAST TO BRING HEAVY
RAIN NEAR THE CALIFORNIA COAST WITH FLASH FLOODING POTENTIALS...
WITH THE DEPARTURE OF THE LOW PRESSURE SYSTEM FURTHER AWAY INTO
SOUTHEASTERN CANADA, A RELATIVELY QUIET WEATHER PATTERN IS
EXPECTED TO PREVAIL ACROSS THE EASTERN TWO-THIRDS OF THE COUNTRY
UNDER THE INFLUENCE OF A COOL AND STABLE HIGH PRESSURE SYSTEM.
THE MOST ACTIVE WEATHER WILL BE FOUND ALONG THE WEST COAST WHERE A
LOW PRESSURE SYSTEM IS FORECAST TO STAY NOT TOO FAR OFFSHORE WHILE
MOVING VERY SLOWLY TO THE SOUTH THROUGH THE NEXT FEW DAYS. RAIN
WILL BE THE PRIMARY PRECIPITATION TYPE ASSOCIATED WITH THIS SYSTEM
EXCEPT WET SNOW EXPECTED OVER THE HIGHER ELEVATIONS ALONG THE
SIERRA NEVADA. THE HEAVIEST RAINFALL IS EXPECTED TO IMPACT AREAS
NEAR THE COAST OF CALIFORNIA FROM NORTH TO SOUTH AS THE SYSTEM
DIPS GENERALLY SOUTHWARD. RAINFALL AMOUNTS ARE FORECAST TO BE 1
TO 2 INCHES WITH LOCALLY HIGHER AMOUNTS NEAR THE COAST OF NORTHERN
TO CENTRAL CALIFORNIA TONIGHT INTO WEDNESDAY BEFORE SHIFTING
SOUTHWARD INTO THE COASTAL SECTIONS OF SOUTHERN CALIFORNIA, WHERE
A HIGHER CHANCE OF HEAVY RAIN WITH LOCALLY A FEW INCHES OF
RAINFALL TOTALS POSSIBLE ON THURSDAY. FLASH FLOODING MAY BECOME
AN ISSUE GIVEN THESE FORECAST RAINFALL AMOUNTS.
MEANWHILE, THE RAIN/HIGH-ELEVATION SNOW INITIALLY ASSOCIATED WITH
A WEAKENING SYSTEM ACROSS THE PACIFIC NORTHWEST IS EXPECTED TO
TAPER OFF TONIGHT AS THE SYSTEM DISSIPATES. BY THURSDAY, MOISTURE
RETURNING FROM THE GULF OF MEXICO BEHIND THE EASTWARD-SLIDING HIGH
PRESSURE SYSTEM IN CONJUNCTION WITH AN UPPER-LEVEL SHORTWAVE
EXITING THE SOUTHERN ROCKIES WILL INCREASE THE CHANCE OF SHOWERS
AND EMBEDDED THUNDERSTORMS TO DEVELOP AND EXPAND FROM THE SOUTHERN
PLAINS TOWARD THE MID-MISSISSIPPI VALLEY SOUTH OF A STATIONARY
FRONT AND EAST F A LEE-SIDE TROUGH. LAKE-EFFECT SNOW SHOWERS NEAR
THE LOWER GREAT LAKES ARE EXPECTED TO GRADUALLY TAPER OFF TONIGHT.
THE EASTERN AND SOUTHEASTERN QUADRANT OF THE COUNTRY WILL BE
COOLER THAN NORMAL THROUGH THURSDAY UNDER THE COOL HIGH PRESSURE
SYSTEM. HOWEVER, MILDER THAN NORMAL TEMPERATURES OVER THE
REMAINDER OF THE COUNTRY WILL BEGIN TO EXPAND EASTWARD WITH TIME
AND GRADUALLY SHRINK THE COOL AIR AND CONFINE THEM TO THE VICINITY
OF FLORIDA BY THURSDAY.
KONG
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