407
FXUS01 KWBC 091937
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 PM EST MON DEC 09 2024
VALID 00Z TUE DEC 10 2024 - 00Z THU DEC 12 2024
...WIDESPREAD HEAVY RAIN THREAT FROM THE CENTRAL TO EASTERN GULF
COAST REGION, NORTHEASTWARD ACROSS ALL OF THE EAST...
...ACTIVE LAKE EFFECT SNOWS TO BEGIN WEDNESDAY AND CONTINUE
THROUGH THURSDAY DOWNWIND OF THE LAKES...
...RECORD WARM MORNING LOWS LIKELY ALONG THE EAST COAST WEDNESDAY
MORNING...
...ARCTIC AIR TO SURGE SOUTH INTO THE NORTHERN PLAINS/UPPER
MISSISSIPPI VALLEY REGION LATE TUESDAY INTO WEDNESDAY...
...CRITICAL TO EXTREME FIRE WEATHER DANGER ACROSS PORTIONS OF
SOUTHERN CALIFORNIA...
THE UPPER LEVEL FLOW WILL UNDERGO SIGNIFICANT AMPLIFICATION ACROSS
MUCH OF NORTH AMERICA OVER THE NEXT FEW DAYS, PRODUCING ACTIVE AND
IMPACTFUL WEATHER EVENTS ACROSS NEARLY ALL OF THE LOWER 48. THIS
AMPLIFYING PATTERN WILL BE COMPRISED OF A BUILDING UPPER RIDGE
ALONG THE WEST COAST AND A DEEPENING UPPER TROF ACROSS THE CENTRAL
TO EASTERN U.S. PRECIPITATION CURRENTLY FALLING ACROSS PORTIONS
OF THE CENTRAL TO EASTERN GULF COAST AND THE NORTHEAST WILL BE
FOLLOWED A MORE WIDESPREAD HEAVY PRECIPITATION EVENT DEVELOPING
TUESDAY NIGHT INTO EARLY WEDNESDAY FROM THE CENTRAL GULF COAST
INTO THE UPPER OHIO VALLEY. THIS AREA OF PRECIPITATION WILL
CONTINUE TO EXPAND EASTWARD DURING THE DAY WEDNESDAY ACROSS ALL OF
THE EAST, PRODUCING WIDESPREAD HEAVY PRECIPITATION FROM THE
CENTRAL TO EASTERN GULF COAST, ACROSS THE SOUTHEAST, MID-ATLANTIC,
NORTHEAST AND NEW ENGLAND. WITH MUCH OF THESE AREAS CURRENTLY IN
MODERATE TO EXTREME DROUGHT CONDITIONS, THIS RAINFALL WILL BE
BENEFICIAL. STILL, GIVEN THE POTENTIAL FOR PERIODS OF HEAVY RAINS
OVER A SHORT PERIOD, THERE WILL BE A THREAT OF LOCALIZED FLASH
FLOODING, ESPECIALLY IN MORE URBANIZED REGIONS.
THIS HEAVY RAIN WILL BE OCCURRING ALONG AND AHEAD OF A STRONG
FRONT PUSHING EAST ACROSS THE EASTERN U.S. ON WEDNESDAY. AHEAD OF
THIS FRONT, THERE IS THE POTENTIAL FOR WIDESPREAD RECORD HIGH
MORNING LOW TEMPERATURES ON WEDNESDAY ACROSS THE SOUTHERN
MID-ATLANTIC, MID-ATLANTIC AND PORTIONS OF THE NORTHEAST. IN THE
WAKE OF THIS FRONT, MUCH COLDER TEMPERATURES WILL BEGIN TO PUSH
ACROSS THE GREAT LAKES FROM WEST TO EAST, BEGINNING ON WEDNESDAY.
THIS WILL IGNITE ACTIVE LAKE EFFECT SNOWS, INITIALLY DOWNWIND OF
LAKES SUPERIOR AND MICHIGAN ON WEDNESDAY AND THEN DOWNWIND OF
LAKES ERIE AND ONTARIO WEDNESDAY NIGHT INTO EARLY THURSDAY.
BEFORE THESE LAKE EFFECT SNOWS DIMINISH BY EARLY FRIDAY, SNOWFALL
TOTALS OF 1 TO 2 FEET ARE POSSIBLE IN THE FAVORED LAKE EFFECT SNOW
REGIONS ACROSS PORTIONS OF NORTHWEST AND WESTERN NEW YORK STATE,
FAR NORTHWEST PENNSYLVANIA, FAR NORTHEASTERN OHIO, THE UPPER
PENINSULA OF MICHIGAN AND THE WESTERN PORTIONS OF THE LOWER
PENINSULA OF MICHIGAN.
THE ABOVE MENTIONED LAKE EFFECT SNOWS WILL BE DRIVEN BY ARCTIC AIR
THAT WILL BE FIRST SURGING EAST SOUTHEASTWARD LATE TUESDAY INTO
EARLY WEDNESDAY ACROSS THE NORTHERN PLAINS INTO THE UPPER
MISSISSIPPI VALLEY AND THEN EASTWARD TROUGH THE GREAT LAKES INTO
THE OHIO VALLEY ON WEDNESDAY. WHILE THERE ARE NOT EXPECTED TO BE
ANY RECORDS WITH THIS ARCTIC OUTBREAK, TEMPERATURES WILL BE MUCH
BELOW AVERAGE ON WEDNESDAY ACROSS THE NORTHERN PLAINS INTO THE
UPPER MISSISSIPPI VALLEY. THESE MUCH BELOW AVERAGE TEMPERATURES
WILL THEN PUSH FARTHER SOUTHEAST INTO THE GREAT LAKES AND OHIO
VALLEY REGION ON THURSDAY. ACROSS THESE REGIONS, HIGH
TEMPERATURES WILL BE 10 TO 25 DEGREES BELOW AVERAGE DURING THE
HEIGHT OF THE COLD TEMPERATURES DURING WEDNESDAY AND THURSDAY.
IN CONTRAST TO THE WET AND COLD CONDITIONS ACROSS PORTIONS OF THE
NORTH CENTRAL TO EASTERN U.S., DRY CONDITION AND MILDER
TEMPERATURES ARE IN STORE ACROSS THE WEST COAST, GREAT BASIN AND
ROCKIES REGION. HOWEVER, THE DRY AIR, LOW RELATIVE HUMIDITIES AND
WINDY SANTA ANA CONDITIONS OVER SOUTHERN CALIFORNIA WILL PRODUCE
CRITICAL TO LOCALLY EXTREME FIRE WEATHER CONDITIONS. THESE FIRE
WEATHER CONDITIONS WILL BE GREATEST IN THE HIGHER TERRAIN AREAS TO
THE NORTH AND EAST OF THE LOS ANGELES TO SAN DIEGO REGION. WINDS
OF 35 TO 45 MPH IN THE VALLEYS AND GUSTS OF 50 TO 65 MPH IN THE
MOUNTAINS WILL HELP FAN ANY FIRES THAT DO DEVELOP QUICKLY AND MAY
REDUCE VISIBILITY WITH BLOWING SMOKE AND DUST ADDING TO TRAVEL
CONCERNS IN THE REGION. ACROSS THESE AREAS, RED FLAG WARNINGS ARE
CURRENTLY IN EFFECT, AFFECTING NEARLY 13 MILLION PEOPLE.
ORAVEC
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