683
FXUS01 KWBC 071912
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 PM EDT THU SEP 07 2023
VALID 00Z FRI SEP 08 2023 - 00Z SUN SEP 10 2023
...THERE ARE SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
NORTHEAST AND MID-ATLANTIC/CENTRAL APPALACHIANS TODAY AND
TOMORROW, WITH A RISK TOMORROW (FRIDAY) AS WELL OVER THE LOWER
MISSISSIPPI RIVER VALLEY...
...THERE ARE EXCESSIVE HEAT WARNINGS OVER PARTS OF NORTHEAST
TEXAS INCLUDING DALLAS/FORT WORTH, AS WELL AS, THE SOUTHWEST
DESERTS OF ARIZONA AND CALIFORNIA INTO SATURDAY. HEAT ADVISORIES
COVER MUCH OF THE REST OF TEXAS INTO THE LOWER MISSISSIPPI VALLEY
AND ACROSS THE MID-ATLANTIC AND NEW ENGLAND TODAY...
...AIR QUALITY ALERTS OVER PARTS OF THE CENTRAL PLAINS, UPPER
MISSISSIPPI VALLEY AND RED RIVER VALLEY OF THE NORTH...
THE STRONG MID TO UPPER LEVEL FLOW WILL CONTINUE TO PRESS EASTWARD
ACROSS SOUTHEAST CANADA, HELPING TO PRESS A COLD FRONT THROUGH THE
GREAT LAKES INTO THE NORTHEAST TODAY INTO TOMORROW. GIVEN THE
FLOW WEAKENS ALOFT, THE FRONT STARTS TO STALL ACROSS THE
APPALACHIAN CHAIN INTO THE EASTER SLOPES LEAVING UNSETTLED WEATHER
LIKELY ACROSS THE EASTERN US, THIS WILL PRESS THE EXTREME HEAT
OFFSHORE BY SATURDAY; THOUGH TEMPERATURES SHOULD MODERATE A BIT ON
FRIDAY COMPARED TO TODAY. HIGH TEMPERATURES AND VERY HIGH
HUMIDITY CONTINUES TO SUPPORT HEAT ADVISORIES TO CONTINUE TODAY
FOR MUCH OF THE MID-ATLANTIC INTO NEW ENGLAND SUPPORTING THE
POTENTIAL FOR SCATTERED SEVERE THUNDERSTORMS WITH INCIDENTS OF
LARGE HAIL AND DAMAGING WINDS AS THE PRIMARY THREAT. THE STORM
PREDICTION CENTER (SPC) HAS ISSUED A SLIGHT RISK TODAY FROM VT/E
NY INTO NORTHERN VIRGINIA WITH A MARGINAL RISK EXTENDING INTO THE
FLORIDA PANHANDLE. SOME OF THESE MAY INDUCE LOCALIZED VERY HEAVY
RAINFALL AND WIDELY SCATTERED INSTANCES OF FLASH FLOODING (WEATHER
PREDICTION CENTER HAS ISSUED A MARGINAL RISK OF EXCESSIVE RAINFALL
FOR SIMILAR AREAS). A SIMILAR SLIGHT RISK FROM SPC AND MARGINAL
RISK FROM WPC WILL EXIST TOMORROW/FRIDAY, THOUGH MORE CONFINED TO
THE MID-ATLANTIC AND NORTHEAST. BY SATURDAY, THE MUCH OF THE
HIGHEST HEAT, UNSTABLE AIR IS LIKELY TO HAVE BEEN PRESSED EAST
FURTHER LIMITING SEVERE THREATS EVEN THOUGH THERE SHOULD BE
SCATTERED SHOWERS/THUNDERSTORMS ALONG/AHEAD OF THE STALLED FRONT.
FURTHER SOUTH ACROSS THE GULF COAST, THE SAME FRONTAL SYSTEM WILL
PRESS INTO AND THROUGH THE FLORIDA PANHANDLE TODAY, BUT A WEAK
SURFACE WAVE ALONG THE EASTERN SIDE OF THE PERSISTENT UPPER-LEVEL
RIDGE/HEAT DOME WILL KEEP VERY HIGH TEMPERATURES (OVER 100-105F)
NEARLY 20-25 DEGREES ABOVE NORMAL TO ONCE AGAIN BAKE NORTHERN
TEXAS. EXCESSIVE HEAT WARNINGS ARE IN EFFECT FOR MUCH OF
NORTHEAST TEXAS, INCLUDING THE DALLAS/FORT WORTH REGION. THESE ARE
VERY DANGEROUS CONDITIONS TO BE OUTSIDE FOR PROLONGED PERIODS,
SEEK SHADE AND KEEP HYDRATED IF REQUIRED TO BE OUTDOORS TODAY AND
INTO TOMORROW (FRIDAY). NEARER THE COAST, THE RETURN FLOW WILL
BE OFF THE WESTERN GULF OF MEXICO AND BRING HIGHER DEWPOINTS AND
POTENTIAL FOR INCREASED THUNDERSTORM ACTIVITY ACROSS SOUTHEAST
TEXAS INTO THE LOWER MISSISSIPPI VALLEY. SPC HAS A SLIGHT RISK OF
SEVERE THUNDERSTORMS FOR FRIDAY FROM THE TEXARKANA REGION THOUGH
THE SABINE RIVER VALLEY. IF THERE IS SOME POSITIVE OUTLOOK, THE
CENTER OF THE RIDGE WILL PRESS WESTWARD INTO NEW MEXICO BY LATE
FRIDAY/SATURDAY ALLOWING FOR THE FRONT TO DROP SOUTH. HOWEVER,
THIS WILL JUST PRESS THE ABOVE AVERAGE HEAT TOWARD THE
BOARDERLANDS WITH MEXICO, AND INCREASE HIGH HEAT FOR THE DESERT
SOUTHWEST. TEMPERATURES WILL ONCE AGAIN REACH THE 110S AND THE
NATIONAL WEATHER SERVICE FORECAST OFFICES HAVE HOISTED AN
EXCESSIVE HEAT WARNING FOR SATURDAY INTO SUNDAY FOR PARTS OF
SOUTHEAST CALIFORNIA AND SOUTHERN ARIZONA, INCLUDING PALM SPRINGS,
YUMA, PHOENIX AND TUCSON.
ELSEWHERE, BEHIND THE FRONT, THE GREAT LAKES AND OHIO VALLEY
SHOULD SEE A REPRIEVE FROM THE HEAT WITH EVEN UNSEASONABLY COOL
AIR BRINGING HIGHS IN THE 60S AND LOWER 70S NEARING 80 ALONG THE
OHIO RIVER TODAY AND TOMORROW, GENERALLY 5-15 DEGREES BELOW
NORMAL.
ADDITIONALLY, AIR QUALITY ALERTS REMAIN IN EFFECT ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID-MISSOURI VALLEY AND THE RED RIVER OF
THE NORTH, DUE TO SOME STAGNANT AIR BUT ALSO RETURN OF THICKER
CANADIAN SMOKE THAT IS DRIFTING DOWNWARD TOWARD THE SURFACE
INCREASING RESPIRATORY STRAIN. THE GOOD NEWS, A COLD FRONT
ACROSS THE HIGH PLAINS OF MT/SOUTHERN PRAIRIES OF CANADA WILL
CONTINUE TO DROP SOUTHWARD OVER THE NEXT FEW DAYS. WHILE THERE IS
SOME SMOKE LIKELY BEHIND THE FRONT, A MUCH COOLER AIRMASS AND
FASTER MOVING AIR MAY ALLOW FOR SOME MODEST IMPROVEMENT WITH LESS
STAGNATION. TEMPERATURES BY SATURDAY WILL BE ONLY INTO THE 70S
AND SPOTS OF UPPER 60S FOR HIGHS ACROSS THE DAKOTAS (ABOVE 10 TO
20 DEGREES BELOW AVERAGE).
GALLINA
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