054
FXUS01 KWBC 210756
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
355 AM EDT THU SEP 21 2023
VALID 12Z THU SEP 21 2023 - 12Z SAT SEP 23 2023
...BELOW-NORMAL TEMPERATURES EXPECTED ACROSS MUCH OF THE WESTERN
U.S., WITH WIDESPREAD PRECIPITATION OVER THE NORTHERN
INTERMOUNTAIN WEST AND ROCKIES...
...STRONG TO SEVERE THUNDERSTORMS AND EXCESSIVE RAINFALL EXPECTED
FOR PORTIONS OF THE NORTHERN & SOUTHERN PLAINS...
...GUSTY WINDS, HEAVY RAIN, AND HIGH SURF LIKELY FOR PORTIONS OF
THE SOUTHEAST AND SOUTHERN MID-ATLANTIC FRIDAY AND INTO THE
WEEKEND..
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 ARE COLD ENOUGH
THAT PARTS OF SOUTHERN OREGON AND NORTHERN CALIFORNIA ARE UNDER
FROST ADVISORIES AND FREEZE WARNINGS THIS MORNING. THERE ARE ALSO
WINTER WEATHER ADVISORIES IN PARTS OF THE NORTHERN ROCKIES THAT
ARE IN EFFECT THROUGH THURSDAY EVENING WHERE A FEW INCHES OF SNOW
ARE POSSIBLE IN THE HIGHEST ELEVATIONS. DAYTIME HIGH TEMPERATURE
ANOMALIES TODAY 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 TODAY AND FRIDAY. ON
THE FLIP-SIDE, GUSTY AND DRY CONDITIONS ARE KEY COGS IN AN
ELEVATED FIRE WEATHER RISK IN PARTS OF NORTHERN CALIFORNIA TODAY.
IN THE NATION'S HEARTLAND, 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. A PAIR OF FRONTAL BOUNDARIES; ONE IN THE
SOUTHERN PLAINS AND THE OTHER IN 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 TODAY IN
THE SOUTHERN AND NORTHERN PLAINS. BY FRIDAY, AS THE UPPER LOW
TRACKS A LITTLE FARTHER EAST, THE EXCESSIVE RAINFALL AND SEVERE
WEATHER THREAT BECOMES POSITIONED OVER 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.
IN THE EAST, THE SPOTLIGHT SHINES BRIGHTEST ON A FRONTAL SYSTEM
OFF THE SOUTHEAST COAST THAT IS FORECAST TO DIRECT A SLUG OF RICH
SUBTROPICAL MOISTURE FROM THE CAROLINA COAST TODAY TO THE COASTAL
MID-ATLANTIC ON FRIDAY. A NARROW MARGINAL RISK FOR EXCESSIVE
RAINFALL EXTENDING FROM SOUTH FLORIDA TO SOUTHERN SOUTH CAROLINA
TODAY GROWS ON FRIDAY TO ENCOMPASS MOST OF THE HEAVILY URBANIZED
MID-ATLANTIC ON SATURDAY. THERE IS A SLIGHT RISK IN PLACE FROM
MYRTLE BEACH SC ON NORTH TO THE SOUTHERN NEW JERSEY SHORE ON
SATURDAY. THERE STILL REMAINS SOME UNCERTAINTY ON STORM TRACK; A
FARTHER INLAND TRACK WOULD BRING HEAVY RAINFALL FARTHER WEST INTO
THE CENTRAL APPALACHIANS BY THE START OF THE WEEKEND. THE ASPECT
OF THE FORECAST THAT HAS GREATER CONFIDENCE IN CAUSING DETRIMENTAL
IMPACTS ARE GUSTY WINDS AND BATTERING SURF THAT MAY RESULT IN
COASTAL FLOODING ALONG THE MID-ATLANTIC COAST. THIS AREA OF LOW
PRESSURE OFF THE MID-ATLANTIC COAST HAS BEEN DESIGNATED WITH A 40%
CHANCE FOR TROPICAL DEVELOPMENT OVER THE NEXT 7 DAYS. AFTER A
SEASONALLY MILD DAY TODAY ALONG THE EAST COAST, THE SURGE IN
HIGH-MID LEVEL CLOUDS AND PERIODS OF RAIN SHOULD LEAD TO MORE
OCTOBER-LIKE TEMPERATURES FROM THE MID-ATLANTIC TO NEW ENGLAND
THIS FRIDAY AND INTO THE UPCOMING WEEKEND.
MULLINAX
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