317
FXUS01 KWBC 210747
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 AM EST THU NOV 21 2024
VALID 12Z THU NOV 21 2024 - 12Z SAT NOV 23 2024
...STRONG ATMOSPHERIC RIVER CONTINUES TO IMPACT NORTHERN
CALIFORNIA WITH HEAVY RAIN AND LIFE-THREATENING FLOODING THROUGH
FRIDAY...
...DEVELOPING STORM SYSTEM FORECAST TO BRING ANOTHER ROUND OF
GUSTY WINDS TO THE PACIFIC NORTHWEST ON FRIDAY WITH HEAVY MOUNTAIN
SNOW SPREADING TOWARD THE NORTHERN ROCKIES THIS WEEKEND...
...UNSETTLED WEATHER EXPECTED ACROSS MUCH OF THE NORTHEAST AND
GREAT LAKES OVER THE NEXT FEW DAYS, INCLUDING THE LIKELIHOOD OF
HEAVY SNOW IN THE CENTRAL APPALACHIANS AND HIGHER ELEVATIONS OF
NORTHEASTERN PENNSYLVANIA AND SOUTHERN NEW YORK...
IMPACTFUL AND FOR SOME PLACE DANGEROUS WEATHER CONDITIONS WILL
CONTINUE THROUGH EARLY THIS WEEKEND AS TWO SEPARATE STORM SYSTEMS
IMPACT THE LOWER 48. STARTING IN THE WEST, A STRONG ATMOSPHERIC
RIVER CURRENTLY IMPACTING NORTHERN CALIFORNIA IS FORECAST TO
REMAIN RELATIVELY STATIONARY OVER THE NEXT FEW DAYS AND PRODUCE AN
ADDITIONAL 6-12 INCHES OF RAINFALL OVER REGIONS WITH ALREADY
SATURATED TERRAIN. THE ATMOSPHERIC RIVER IS EXPECTED TO PEAK IN
INTENSITY TODAY, BUT WITH MODERATE BOUTS OF RAIN LINGERING THROUGH
MUCH OF FRIDAY AND SNOW LEVELS FINALLY LOWERING SOMEWHAT ON
SATURDAY. IN THE MEANTIME, DANGEROUS FLOODING, ROCK SLIDES, AND
DEBRIS FLOWS ARE LIKELY, WHICH HAS PROMPTED A HIGH RISK (LEVEL
4/4) OF EXCESSIVE RAINFALL TO BE ISSUED ACROSS THE NORTHERN
CALIFORNIA COASTLINE TODAY. BE SURE TO CHECK CONDITIONS BEFORE
TRAVELING AND NEVER DRIVE ACROSS FLOODED ROADWAYS.
AIDING THE SURGE OF ATMOSPHERIC MOISTURE INTO NORTHERN CALIFORNIA
AND THE NORTHWEST THROUGH THE END OF THE WEEK IS A DEVELOPING
STORM SYSTEM FORECAST TO SWING OFF THE OREGON AND WASHINGTON
COASTLINE ON FRIDAY. A PUNCH OF GUSTY WINDS ARE EXPECTED, MAINLY
ALONG COASTAL REGIONS, COULD PRODUCE ROUGH SURF AND ADDITIONAL
ISOLATED POWER OUTAGES. AS PRECIPITATION LIFTS NORTHWARD AND
INLAND ALONG A DRAPED STATIONARY BOUNDARY STRETCHING FROM THE
NORTHERN ROCKIES TO BRITISH COLUMBIA, HEAVY SNOW IS POSSIBLE FROM
THE WASHINGTON CASCADES TO THE WESTERN MONTANA, IDAHO, AND
NORTHWESTERN WYOMING MOUNTAIN RANGES THROUGH EARLY SUNDAY.
NOVEMBER SNOWFALL IS ALSO IN THE FORECAST FOR PARTS OF THE
NORTHEAST AND GREAT LAKES THANKS TO A POTENT UPPER-LEVEL LOW
SWINGING OVER THE REGION. AT THE SURFACE, A COMPACT AREA OF LOW
PRESSURE IS CURRENTLY LOOPING AROUND THE GREAT LAKES WITH AN
EVENTUAL SOUTHWARD TRAJECTORY OVER LAKE MICHIGAN LATER TODAY.
PARTS OF EASTERN WISCONSIN COULD SEE PRECIPITATION FALL AS SNOW
ALONG WITH WIND GUSTS UP TO 40 MPH. WINTER WEATHER ADVISORIES HAVE
BEEN ISSUED FOR SNOWFALL AMOUNTS UP TO 3-4 INCHES. MEANWHILE, A
SEPARATE AREA OF LOW PRESSURE DEVELOPING NEAR LONG ISLAND TONIGHT
IS ALSO EXPECTED TO TRACK IN A LOOPING ORIENTATION ACROSS THE
NORTHEAST THROUGH FRIDAY, WHILE ALSO PRODUCING PERIODS OF HEAVY
SNOW. THE GREATEST CHANCES FOR AT LEAST 6 INCHES OF SNOWFALL IS
FOUND ACROSS NORTHEAST PENNSYLVANIA AND SOUTHERN NEW YORK,
INCLUDING THE POCONO AND CATSKILL MOUNTAINS. ADDITIONALLY, A
LONG-DURATION UPSLOPE SNOW EVENT IS UNDERWAY ACROSS THE CENTRAL
APPALACHIANS AND ANTICIPATED TO LINGER THROUGH AT LEAST EARLY
SATURDAY. UP TO A FOOT OF SNOW IS POSSIBLE ACROSS THE HIGHER
TERRAIN OF WEST VIRGINIA, MARYLAND, AND SOUTHWEST PENNSYLVANIA.
LIGHT SNOW IS ALSO EXPECTED TO REACH AS FAR SOUTH AS THE HIGHER
RANGES OF NORTH CAROLINA.
THE CENTRAL AND SOUTHERN U.S. CAN EXPECT MUCH MORE TRANQUIL
CONDITIONS AS HIGH PRESSURE CREATES A VOID IN THE UNSETTLED
WEATHER IMPACTING BOTH THE EAST AND WEST COASTS. HOWEVER, BELOW
AVERAGE TEMPERATURES ARE FORECAST FROM THE MISSISSIPPI VALLEY TO
THE SOUTHEAST AS BREEZY NORTHWEST FLOW USHERS IN A COLDER AIRMASS.
THIS MAY LEAD TO EARLY MORNING FROST AND/OR FREEZE POTENTIAL
ACROSS THE SOUTHEAST AND LOWER MISSISSIPPI VALLEY.
SNELL
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