228
FXUS01 KWBC 212020
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT THU SEP 21 2023
VALID 00Z FRI SEP 22 2023 - 00Z SUN SEP 24 2023
...POTENTIAL TROPICAL CYCLONE SIXTEEN IS FORECAST TO BECOME A
TROPICAL STORM, SPREADING HEAVY RAIN UP THE EAST COAST AND
TROPICAL-STORM-FORCE WINDS NEAR/ALONG THE COAST...
...BOUTS OF STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO IMPACT
PORTIONS OF THE CENTRAL U.S. AS HEAVY/EXCESSIVE RAINFALL DEVELOPS
ACROSS THE NORTHERN PLAINS TOWARD THE MIDWEST...
...COLDER THAN NORMAL CONDITIONS WILL EXPAND ACROSS THE WESTERN
U.S. AS HIGH-ELEVATION SNOW AND WET SNOW GRADUALLY TAPER OFF
ACROSS THE INTERMOUNTAIN REGION...
POTENTIAL TROPICAL CYCLONE SIXTEEN BECAME THE SPOTLIGHT THIS
MORNING AS THE NATIONAL HURRICANE CENTER BEGAN ISSUING ADVISORY ON
THIS DEVELOPING SYSTEM OFF THE COAST OF SOUTHEASTERN U.S. THIS
SYSTEM IS FORECAST TO INTENSIFY AS IT TRACKS GENERALLY NORTHWARD,
EDGING TOWARD THE MID-ATLANTIC COAST THROUGH THE NEXT COUPLE DAYS.
AS THE CORE OF THE SYSTEM MOVES OVER THE WARM GULF STREAM
UNDERNEATH A COLD UPPER TROUGH WHILE INTERACTING WITH A FRONTAL
ZONAL NEAR/OFF THE EAST COAST, HEAVY RAIN IS FORECAST TO GRADUALLY
OVERSPREAD THE MID-ATLANTIC REGION LATER ON FRIDAY AND FRIDAY
NIGHT, AND THEN FARTHER NORTH INTO SOUTHERN NEW ENGLAND ON
SATURDAY. THE CORE OF THE SYSTEM WILL BE PRONE TO FURTHER ACQUIRE
TROPICAL CHARACTERISTICS AS IT MOVES OVER THE WARM WATERS OFF THE
SOUTHEAST U.S. THROUGH FRIDAY NIGHT. THIS WILL ALLOW THE SYSTEM
TO GAIN STRENGTH THROUGH FRIDAY NIGHT AND MAKE LANDFALL
POTENTIALLY AS A TROPICAL STORM OVER EASTERN NORTH CAROLINA EARLY
ON SATURDAY. SQUALLY HEAVY RAIN IS FORECAST TO INTENSIFY ALONG
THE MID-ATLANTIC COAST THROUGH FRIDAY AS THE STORM APPROACHES.
THE CENTER OF THE STORM COULD POTENTIALLY TRACK FURTHER UP THE
CHESAPEAKE BAY ON SATURDAY, SPREADING HEAVY RAIN AND GALE FORCE
WIND FARTHER INLAND AS WELL AS UP THE EAST COAST AS GENERAL
WEAKENING IS FORECAST TO BEGIN.
MEANWHILE, A POTENT UPPER LEVEL TROUGH OVER THE NORTHWESTERN U.S.
WILL BE RESPONSIBLE FOR AN ABNORMALLY COOL TEMPERATURE REGIME
THROUGHOUT THE SECOND HALF OF THE WORK WEEK. TEMPERATURES WERE
COLD ENOUGH THAT PARTS OF SOUTHERN OREGON AND NORTHERN CALIFORNIA
ARE UNDER FROST ADVISORIES AND FREEZE WARNINGS THIS MORNING.
WINTER WEATHER ADVISORIES REMAIN IN EFFECT FOR PARTS OF THE
NORTHERN ROCKIES THROUGH THIS EVENING WHERE A FEW INCHES OF SNOW
ARE POSSIBLE IN THE HIGHEST ELEVATIONS. DAYTIME HIGH TEMPERATURE
ANOMALIES WILL RANGE BETWEEN 15 TO 25 DEGREES BELOW NORMAL FROM
THE NORTHERN ROCKIES TO SOUTHERN CALIFORNIA. THE STORM SYSTEM
TRAVERSING THE INTERMOUNTAIN WEST WILL ALSO TRIGGER SHOWERS AND
STORMS INTO PARTS OF THE INTERMOUNTAIN WEST INTO FRIDAY BEFORE
TAPERING OFF ON SATURDAY AS THE STORM MOVES OUT INTO THE PLAINS.
ON THE FLIP-SIDE, GUSTY AND DRY CONDITIONS ARE KEY COGS IN AN
ELEVATED FIRE WEATHER RISK IN PARTS OF NORTHERN CALIFORNIA THROUGH
THIS EVENING.
THE AFOREMENTIONED UPPER LOW IN THE NORTHWEST WILL ALSO PLAY A
ROLE IN WHAT LOOKS TO BE A WET AND STORMY END TO THE WEEK OVER A
GOOD PORTION OF THE CENTRAL U.S.. A PAIR OF FRONTAL BOUNDARIES;
ONE ACROSS THE SOUTHERN PLAINS AND THE OTHER ACROSS THE NORTHERN
PLAINS ARE GOING TO HELP SPARK WIDESPREAD HEAVY SHOWERS AND
STORMS. THERE ARE A PAIR OF SLIGHT RISKS FOR EXCESSIVE RAINFALL
AND SEVERE WEATHER OVER PORTIONS OF THE SOUTHERN AND NORTHERN
PLAINS. BY FRIDAY, AS THE UPPER LOW TRACKS A LITTLE FARTHER EAST,
THE EXCESSIVE RAINFALL AND SEVERE WEATHER THREAT WILL LIKELY
OVERSPREAD A GOOD PORTION OF THE NORTHERN PLAINS. FROM A SEVERE
WEATHER STANDPOINT, LARGE HAIL AND DAMAGING WIND GUSTS ARE THE
PRIMARY CONCERNS, ALTHOUGH SOME SEVERE STORMS COULD ALSO PRODUCE
TORNADOES. IN THE SOUTHERN PLAINS, SUMMER-LIKE HEAT REMAINS IN THE
FORECAST AS DAYTIME HIGHS ROUTINELY REACH THE 90S THROUGHOUT THE
VAST MAJORITY OF TEXAS THROUGH FRIDAY. THE STORM PREDICTION CENTER
(SPC) HAS ALSO ISSUED AN ELEVATED THREAT AREA FOR FIRE WEATHER IN
THE SOUTHERN HIGH PLAINS ON FRIDAY. BY SATURDAY, THE FOCUS OF
HEAVY RAIN WILL LIKELY SHIFT FARTHER EAST AND SOUTHEAST FROM THE
NORTHERN PLAINS DOWN TOWARD EASTERN OKLAHOMA AHEAD OF AN ELONGATED
LOW PRESSURE SYSTEM THAT IS FORECAST TO CONSOLIDATE OVER THE
CENTRAL U.S. SEVERE WEATHER CONCERNS WILL LIKEWISE BE EMBEDDED
WITHIN THIS GENERAL CORRIDOR, AND ESPECIALLY LATER IN THE DAY WHEN
INSTABILITY IS INCREASED BY SOLAR HEATING.
KONG/MULLINAX
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