462
FXUS01 KWBC 180452
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1251 AM EDT FRI SEP 18 2026
VALID 12Z FRI SEP 18 2026 - 12Z SUN SEP 20 2026
...HEAVY RAIN AND FLASH FLOODING CONCERNS OVER NORTH-CENTRAL U.S.
THROUGH THE WEEKEND...
...POTENTIAL RECORD BREAKING HIGH TEMPERATURES CONTINUE ACROSS THE
SOUTH-CENTRAL U.S. THROUGH THE WEEKEND...
A PROGRESSIVE UPPER-LEVEL LOW OVER THE PACIFIC NORTHWEST WILL MOVE
EASTWARD ACROSS THE NORTHERN TIER, BRINGING ACTIVE WEATHER ACROSS
THE NORTHERN ROCKIES INTO THE GREAT LAKES INTO THE WEEKEND. THE
DISTURBANCE WILL HELP PUSH THE FRONTAL BOUNDARY INTO THE
ROCKIES/PLAINS BY FRIDAY, WHICH WILL PROVIDE THE PRIMARY FORCING
FOR SHOWERS AND THUNDERSTORMS. A DEEP PLUME OF WARM MOISTURE WILL
ACCOMPANY THE SYSTEM, WHILE INSTABILITY CONTINUES TO INCREASE
AHEAD OF THE DISTURBANCE. THIS SETUP MAY PRODUCE REPEATED
CONVECTION, WHICH WILL LEAD TO HEAVY RAINFALL AND FLASH FLOODING
CONCERNS ACROSS THE ROCKIES/PLAINS EASTWARD INTO THE UPPER
MISSISSIPPI VALLEY AND MIDWEST. ON SATURDAY, THE SYSTEM CONTINUES
TO PROGRESS EASTWARD INTO THE GREAT LAKES, WHILE A MOIST AND
UNSTABLE AIRMASS REMAINS IN PLACE AHEAD OF THE SYSTEM. THIS WILL
SHIFT THE HEAVY RAINFALL/FLASH FLOODING POTENTIAL INTO PORTIONS OF
THE MIDWEST, OHIO VALLEY, AND LOWER GREAT LAKES THROUGH SATURDAY.
GRADUALLY THE SYSTEM MOVES TOWARDS THE NORTHEAST/MID-ATLANTIC BY
LATE SATURDAY/EARLY SUNDAY.
MEANWHILE, A PORTION OF THE FRONTAL SYSTEM WILL DRAPE SOUTHWARD
ACROSS PORTIONS OF THE MID-ATLANTIC/SOUTHEAST, BRINGING SHOWERS
AND THUNDERSTORMS ALONG THE BOUNDARY. THE COMBINATION OF DEEP
TROPICAL MOISTURE AND SLOW MOVING SYSTEMS, HIGH RAINFALL RATES MAY
LEAD TO EXCESSIVE RAINFALL ACROSS PORTIONS OF FLORIDA THROUGH
SATURDAY. ACROSS THE SOUTHWEST AND FOUR CORNERS, MONSOONAL
ACTIVITY WILL GRADUALLY DECREASE AND SHIFT SLIGHTLY EAST BY
SATURDAY BUT RESIDUAL MOISTURE WILL CONTINUE TO PRODUCE ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS, PARTICULARLY OVER HIGHER
TERRAIN.
IN CONTRAST TO AN ACTIVE NORTHERN TIER, RIDGING OVER THE SOUTHERN
PLAINS AND SOUTHEAST WILL MAINTAIN HOT AND HUMID CONDITIONS ACROSS
MUCH OF THE SOUTH-CENTRAL U.S. TEMPERATURES WILL REMAIN WELL ABOVE
SEASONAL WITH HIGHS IN THE 90S TO LOW 100S, WITH SOME LOCATIONS
POTENTIALLY APPROACHING OR EXCEEDING DAILY RECORD VALUES. WITH
OVERNIGHT LOWS REMAINING WELL IN THE 70S, RECOVERY WILL BE
MINIMUM. THEREFORE, WIDESPREAD MODERATE TO EXTREME HEATRISK WILL
BE FORECASTED THROUGH THE WEEKEND. OTHERWISE, NEAR OR SLIGHTLY
BELOW AVERAGE TEMPERATURES WILL BUILD ACROSS MUCH OF WESTERN U.S.
AND ALONG THE FRONTAL BOUNDARY ACROSS THE NORTHERN TIER.
OUDIT
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