980
FXUS01 KWBC 200745
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
344 AM EDT SUN AUG 20 2023
VALID 12Z SUN AUG 20 2023 - 12Z TUE AUG 22 2023
...HEAVY RAINS ASSOCIATED WITH TROPICAL CYCLONE HILARY ARE LIKELY
TO PRODUCE CATASTROPHIC TO LIFE-THREATENING FLOODING OVER PORTIONS
OF THE SOUTHWEST...
...DANGEROUS HEAT TO CONTINUE TO EXPAND ACROSS THE CENTRAL U.S.
THROUGH THE EARLY PART OF THIS WEEK...
..POTENTIALLY HEAVY RAIN MOVING INTO SOUTHERN TEXAS ON TUESDAY
HURRICANE HILARY CONTINUES TO MOVE NORTH IN THE EASTERN PACIFIC
NEAR THE COAST OF BAJA CALIFORNIA THIS MORNING. RAIN ASSOCIATED
WITH THE SYSTEM HAS BEEN SPREADING NORTH ACROSS PORTIONS OF
SOUTHERN CALIFORNIA AND WESTERN ARIZONA INTO THE GREAT BASIN
OVERNIGHT AND IS LIKELY TO INCREASE IN INTENSITY LATER TODAY AS
THE STORM CONTINUES ITS NORTHWARD TRACK. MOISTURE-LADEN SOUTHERLY
WINDS ARE EXPECTED TO SUPPORT VERY HEAVY RAINFALL, WITH SOME
LOCATIONS LIKELY TO ACCUMULATE RAINFALL TOTALS EXCEEDING THEIR
TYPICAL ANNUAL AMOUNTS IN JUST A MATTER OF HOURS. THIS
POTENTIALLY HISTORIC RAINFALL IS EXPECTED TO CAUSE FLASH, URBAN,
AND ARROYO FLOODING, INCLUDING LANDSLIDES, MUDSLIDES, AND DEBRIS
FLOWS. THESE DANGEROUS TO CATASTROPHIC FLOODING IMPACTS ARE
EXPECTED TO OCCUR TODAY THROUGH EARLY MONDAY. WPC CONTINUES TO
HIGHLIGHT PARTS OF SOUTHERN CALIFORNIA INTO SOUTHERN AND CENTRAL
NEVADA AS THE AREA WHERE THE THREAT FOR NUMEROUS TO WIDESPREAD
FLASH FLOODING IS MOST LIKELY.
IN ADDITION TO HEAVY RAIN, TROPICAL STORMS CONDITIONS ARE EXPECTED
TO BEGIN TODAY ACROSS PORTIONS OF SOUTHERN CALIFORNIA. WINDS
COULD BE PARTICULARLY STRONG AND GUSTY IN AND NEAR AREAS OF HIGHER
TERRAIN. LARGE SWELLS WILL AFFECT PORTIONS OF SOUTHERN CALIFORNIA
OVER THE NEXT COUPLE OF DAYS. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS.
HILARY WILL QUICKLY WEAKEN AS IT MOVES INTO THE INTERIOR SOUTHWEST
TONIGHT. HOWEVER, AMPLE MOISTURE WILL REMAIN, SUPPORTING
WIDESPREAD SHOWERS AND THUNDERSTORMS FROM THE SOUTHWEST THROUGH
THE INTERMOUNTAIN WEST INTO THE NORTHERN ROCKIES ON MONDAY. THESE
STORMS WILL HAVE TO THE POTENTIAL TO PRODUCE ADDITIONAL HEAVY
RAINFALL AMOUNTS AND FLOODING CONCERNS. STRONG AND GUSTY WINDS
WILL REMAIN A THREAT AS WELL FOR PARTS OF THE CENTRAL AND NORTHERN
INTERMOUNTAIN WEST, ESPECIALLY ALONG THE HIGHER TERRAIN.
DANGEROUS HEAT ALREADY IMPACTING PORTIONS OF THE CENTRAL AND
SOUTHERN PLAINS AND THE LOWER MISSISSIPPI VALLEY WILL CONTINUE TO
EXPAND, WITH WELL ABOVE-NORMAL AND RECORD-BREAKING TEMPERATURE
SPREADING ACROSS THE MID MISSISSIPPI VALLEY TODAY. ON MONDAY,
THE HEAT WILL BEGIN TO SPREAD BACK INTO THE NORTHERN PLAINS AND
UPPER MIDWEST, WHERE IT WILL LIKELY REMAIN ENTRENCHED INTO
MIDWEEK. THE PROLONGED NATURE OF THE HEAT WAVE, COMBINED WITH
VERY WARM OVERNIGHT TEMPERATURES WILL OFFER LIMITED RELIEF FROM
THE OPPRESSIVE DAYTIME HEAT -- COMPOUNDING THE OVERALL HEAT
IMPACTS.
ALONG THE GULF COAST, AN AREA OF DISTURBED WEATHER IS EXPECTED TO
MOVE WEST INTO THE GULF OF MEXICO LATER TODAY. THIS SYSTEM IS
FORECAST TO MOVE STEADILY ACROSS THE GULF, NEARING THE TEXAS COAST
EARLY TUESDAY. NHC IS MONITORING THIS SYSTEM, NOTING A TROPICAL
DEPRESSION MAY FORM AS IT APPROACHES THE COAST. REGARDLESS OF
DEVELOPMENT, THE THREAT FOR HEAVY RAINFALL IS EXPECTED TO INCREASE
ACROSS SOUTHERN TEXAS BEGINNING LATE IN THE PERIOD.
MUCH OF THE EASTERN U.S. IS FORECAST TO REMAIN DRY THROUGH THE
PERIOD. DAILY SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS
FLORIDA AND ALONG THE SOUTHEAST COAST. ALSO, SOME LIGHT RAIN MAY
ACCOMPANY A COLD FRONT PUSHING SOUTH ACROSS THE NORTHEAST ON
MONDAY. ABOVE-NORMAL TEMPERATURES ARE EXPECTED TO RETURN TO MUCH
OF THE EASTERN U.S. OVER THE NEXT TWO DAYS, THEN COOLER
TEMPERATURES WILL BEGIN TO SPREAD ACROSS THE NORTHEAST BEHIND THE
COLD FRONT ON TUESDAY.
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