362
FXUS01 KWBC 180646
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 AM EDT FRI JUL 18 2025
VALID 12Z FRI JUL 18 2025 - 12Z SUN JUL 20 2025
...HEIGHTENED FLASH FLOODING THREAT FOR PORTIONS OF THE OHIO
VALLEY, SOUTHERN APPALACHIANS, & MID-ATLANTIC STATES FRIDAY
THROUGH SUNDAY...
...FLASH FLOOD RISK LINGERS ALONG THE CENTRAL GULF COAST ON
FRIDAY...
...WIDESPREAD HEAT ACROSS THE INTERMOUNTAIN WEST, OHIO VALLEY,
SOUTHEAST, AND LOWER MISSISSIPPI VALLEY...
THE FLOW PATTERN IS AN UNUSUAL ONE FOR JULY, WITH A MUCH STRONGER
THAN AVERAGE SUBTROPICAL RIDGE NEAR THE EASTERN GULF (UP TO 3
STANDARD DEVIATIONS STRONGER THAN JULY NORMS), AND A WEAK NEGATIVE
ANOMALY ACROSS THE NORTHERN TIER OF THE COUNTRY CAUSED BY A MORE
SOUTHERLY THAN AVERAGE JET STREAM FOR JULY. THE SQUEEZE PLAY
BETWEEN THESE FEATURES CAUSES THE JET STREAM ITSELF TO BE STRONGER
THAN AVERAGE, WITH OCCASIONAL SPEED MAXIMA OF 120 KTS/140 MPH.
THIS WILL ALLOW SYSTEMS IN THE NORTHERN TIER OF THE COUNTRY TO
REMAIN PROGRESSIVE AND TEMPERATURES NEAR AND TO THE SOUTH OF
SYSTEMS' FRONTS TO REMAIN OPPRESSIVE. IT WILL ALSO FOSTER ABOVE
AVERAGE MOISTURE AVAILABILITY INTO FRONTS DUE TO THE STRONGER THAN
AVERAGE GULF INFLOW/BOUNDARY LAYER MOISTURE CONVERGENCE CAUSED BY
THE ANOMALOUS FLOW PATTERN.
THE FRONT AT THE BASE OF THE WESTERLIES WAVERS AROUND THE OHIO
VALLEY, THE SOUTHERN GREAT LAKES, THE SOUTHERN APPALACHIANS, AND
THE MID-ATLANTIC STATES OVER THE NEXT FEW DAYS, PROVIDING THE
FOCUS FOR THUNDERSTORMS WITH GREATER ORGANIZATION THAN TYPICAL FOR
JULY WHICH LEADS TO BOTH AN ENHANCED FLASH FLOOD RISK AND SEVERE
WEATHER RISK FROM THE MIDWEST EASTWARD AND SOUTHEASTWARD INTO THIS
WEEKEND. THE RISK FOR BOTH SEVERE WEATHER AND FLASH FLOODING ON
FRIDAY IS GREATEST IN THE CORN BELT AND MID-ATLANTIC STATES/NORTH
CAROLINA, AND ON SATURDAY AND SUNDAY THE GREATER FLASH FLOOD RISK
FROM THE CORN BELT ACROSS THE OHIO VALLEY INTO THE SOUTHERN
APPALACHIANS. THE GREATEST SEVERE WEATHER RISK LIES FROM THE CORN
BELT INTO THE SOUTHERN GREAT LAKES ON SATURDAY.
ACROSS PORTIONS OF THE CENTRAL GULF COAST, THE FORMER TROPICAL
DISTURBANCE WILL MARCH FARTHER INLAND, ENHANCING FLASH FLOOD
CONCERNS FOR THE COASTAL PLAIN BETWEEN HOUSTON AND PENSACOLA ON
FRIDAY. THIS SYSTEM ALONG WITH PLENTIFUL GULF MOISTURE IS BEING
PUSHED WEST AND NORTH BY AN ANOMALOUSLY STRONG SUBTROPICAL RIDGE
ACROSS THE EASTERN GULF COAST WHICH DRIFTS WEST EACH DAY. BECAUSE
OF THE STRONG RIDGING ALOFT AND ABOVE AVERAGE GULF MOISTURE
PRESENT, UNCOMFORTABLE HEAT CONTINUES THIS WEEK ACROSS PORTIONS OF
THE MISSISSIPPI VALLEY, OHIO VALLEY, AND THE SOUTHEAST NEAR THE
SOUTH OF THE FRONT. HIGHS INTO THE 90S COMBINED WITH THE VERY
HUMID AIRMASS LEADS TO WIDESPREAD COVERAGE OF MODERATE TO MAJOR
HEAT RISK, VERY PROBLEMATIC FOR THOSE WITHOUT ACCESS TO AIR
CONDITIONING. STAY INSIDE WHEN POSSIBLE AND STAY HYDRATED.
ON THE WESTERN PERIPHERY OF THE GULF MOISTURE, AN ACTIVE MONSOONAL
PATTERN CONTINUES FOR ARIZONA AND PORTIONS OF THE SOUTHERN ROCKIES
THROUGH SUNDAY, WITH SCATTERED THUNDERSTORMS EXPECTED DAILY AND A
THREAT FOR ISOLATED FLASH FLOODING, ESPECIALLY FOR TERRAIN,
SENSITIVE AREAS FROM RECENT RAINS, AND RECENT BURN SCARS. ACROSS
THE INTERIOR NORTHWEST, IT STARTS OUT HOT ON FRIDAY AHEAD OF AN
INCOMING COLD FRONT. BREEZY CONDITIONS ALONG WITH DRYNESS HAS LED
TO THE POSTING OF RED FLAG WARNINGS IN AND NEAR THE COLUMBIA BASIN
AND PORTIONS OF SOUTHERN IDAHO. THE FRONT'S PASSAGE COOLS OFF THE
COLUMBIA BASIN NOTICEABLY BY SATURDAY, THOUGH HEAT REMAINS ACROSS
THE REMAINDER OF THE INTERMOUNTAIN WEST THROUGH AT LEAST SUNDAY.
EVEN STILL, BREEZY CONDITIONS AND LOW RELATIVE HUMIDITIES LEAD TO
AN ELEVATED FIRE RISK CONTINUING IN AND NEAR THE COLUMBIA BASIN,
SOUTHERN IDAHO, AND NORTHERN NEVADA ON SATURDAY. CONDITIONS
FAVORABLE FOR FIRE WEATHER SHIFT TO SOUTHERN IDAHO, FARTHER INTO
NEVADA, AND INTO NORTHEASTERN-MOST CALIFORNIA ON SUNDAY.
ROTH
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