650
FXUS01 KWBC 172040
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
439 PM EDT THU AUG 17 2023
VALID 00Z FRI AUG 18 2023 - 00Z SUN AUG 20 2023
...ANOMALOUS HEAT SHIFTS FROM NORTHWEST INTO NORTHERN/CENTRAL
PLAINS; WIDESPREAD RECORD BREAKING HEAT WAVE PERSISTS ACROSS THE
SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY THROUGH THE WEEKEND...
...SHOWERS, THUNDERSTORMS, AND AN INCREASING RISK OF FLASH
FLOODING FOR THE SOUTHWEST...
...SCATTERED SHOWERS AND THUNDERSTORMS FROM OHIO VALLEY INTO
NORTHEAST THROUGH SATURDAY...
...CRITICAL FIRE WEATHER RISK FOR PORTIONS OF THE PACIFIC
NORTHWEST AND NORTHERN ROCKIES/PLAINS...
AN AMPLIFIED UPPER TROUGH WILL CLOSE-OFF AS IT SPINS THROUGH THE
NORTHEAST AND PARTS OF SOUTHEASTERN CANADA OVER THE NEXT COUPLE OF
DAYS. SCATTERED SHOWERS AND THUNDERSTORMS WILL FOCUS ALONG A
SURFACE COLD FRONT SWEEPING ACROSS THE OHIO VALLEY, NORTHERN
MID-ATLANTIC AND NORTHEAST. RAINFALL RATES SHOULDN'T BE HIGH
ENOUGH TO CAUSE FLASH FLOODING CONCERNS, HOWEVER MARGINAL RISKS
ARE IN EFFECT FOR MUCH OF THE NORTHEAST TO ACCOUNT FOR ANY
POTENTIAL ISOLATED INSTANCES THROUGH FRIDAY NIGHT.
ELSEWHERE, SCATTERED SHOWER AND THUNDERSTORM ACTIVITY WILL IMPACT
PORTIONS OF THE SOUTHWEST, INTERMOUNTAIN WEST AND GREAT BASIN
TONIGHT AS AN UPPER LOW OFF THE CALIFORNIA COAST AND THE CENTRAL
U.S. RIDGE DIRECTS ENERGY INTO THE WEST. MORE IMPACTFUL MOISTURE
WON'T BEGIN TO ARRIVE UNTIL FRIDAY AFTERNOON WHEN SOME AFTERNOON
STORMS MAY PRODUCE INSTANCES OF FLASH FLOODING OVER PARTS OF
NORTHERN ARIZONA AND SOUTHERN UTAH. A SLIGHT RISK OF EXCESSIVE
RAINFALL IS IN EFFECT FOR THE AFOREMENTIONED AREAS, DUE IN PART TO
THE PRESENCE OF SLOT CANYONS, WHICH ARE PRONE TO FLASH FLOODING.
TROPICAL MOISTURE IS LIKELY TO ARRIVE OVER THE SOUTHWEST BEGINNING
SATURDAY NIGHT. HEAVY RAINFALL AND THUNDERSTORMS ARE LIKELY TO
IMPACT PARTS OF SOUTHERN CALIFORNIA INTO SOUTHWESTERN ARIZONA AND
SOUTHERN NEVADA BEGINNING SATURDAY NIGHT.
AN UPPER TROUGH WILL SWING ACROSS SOUTHWESTERN CANADA WHILE AN
UPPER RIDGE EXPANDS OVER THE GREAT PLAINS AND MISSISSIPPI VALLEY
OVER THE NEXT COUPLE OF DAYS. THIS WILL SUPPORT ANOMALOUS WARMTH
TO SPREAD FROM THE NORTHWEST INTO THE NORTHERN/CENTRAL PLAINS
TOMORROW. LOWS IN THE MID-UPPER 60S AND LOW 70S MAY TIE OR BREAK
RECORDS ACROSS THE NORTHWEST TONIGHT. THE HEAT WILL SPREAD INTO
THE PLAINS ON FRIDAY, WHERE HIGH TEMPERATURE ANOMALIES ARE LIKELY
TO BE 10-20 DEGREES ABOVE AVERAGE. WIDESPREAD RECORD BREAKING HEAT
IS EXPECTED TO PERSIST ACROSS THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY THROUGH THIS WEEKEND. TAKE HEAT SERIOUSLY!
AVOID TIME OUTDOORS IN THE HOTTEST TIME OF THE DAY AND ON THE
HOTTEST DAYS, AND HAVE A WAY TO STAY HYDRATED.
KEBEDE
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