909
FXUS02 KWBC 111829
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
229 PM EDT MON AUG 11 2025
VALID 12Z THU AUG 14 2025 - 12Z MON AUG 18 2025
..OVERVIEW
WESTERN TROUGHING AND EASTERN RIDGING WILL BE THE STORY FOR THE
MEDIUM RANGE PERIOD, WITH THE JET STREAM MOSTLY ACROSS SOUTHERN
CANADA. THIS WILL TAKE THE STORM TRACK INTO THE PACIFIC NORTHWEST
THEN THROUGH THE NORTHERN TIER OF THE LOWER 48. TEMPERATURES WILL
GENERALLY FOLLOW SUIT WITH COOLER THAN NORMAL READINGS FOR MUCH OF
THE WEST BUT WARMER THAN NORMAL READINGS FOR MOST OF THE REST OF
THE CONUS. RAINFALL WILL BE FAVORED IN THE PACIFIC NORTHWEST, UPPER
MIDWEST, MID-SOUTH/SOUTHEAST, AND INCREASINGLY IN THE SOUTHWEST AS
THE MONSOON SEASON FINALLY SHOWS SOME LIFE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
UPDATED 00/06Z GUIDANCE REMAINS IN GOOD AGREEMENT ON THE OVERALL
SYNOPTIC PATTERN THROUGH THE MEDIUM RANGE PERIOD COVERING THE END
OF THIS WEEK AND THROUGH THE WEEKEND (THURSDAY AUG 14 - MON AUG
18). RUN-TO-RUN CONSISTENCY IS ALSO WELL MAINTAINED SUGGESTING
ABOVE AVERAGE PREDICTABILITY IN THE PATTERN. ALL GUIDANCE SHOWS THE
STORM TRACK WILL LIFT NORTHWARD OVER THE CENTRAL/EASTERN U.S. AS
AN UPPER- LEVEL HIGH BUILDS OVER THE SOUTHEASTERN AND THEN SOUTH-
CENTRAL U.S. FOLLOWING THE DEPARTURE OF A MID-WEEK SYSTEM OVER THE
NORTHEAST. MEANWHILE, MEAN UPPER- TROUGHING WILL BE IN PLACE OVER
THE NORTHEASTERN PACIFIC INTO THE PACIFIC NORTHWEST, WITH PERIODIC
SHORT-WAVE/SYSTEM ACTIVITY THROUGH THE NORTHWEST AS WELL AS EAST
INTO SOUTHERN CANADA/THE NORTHERN-TIER OF THE U.S. A COMPOSITE
BLEND OF THE DETERMINISTIC GUIDANCE (00Z ECMWF/CMC/UKMET AND 06Z
GFS) REMAINS A GOOD STARTING POINT FOR THE UPDATED WPC FORECAST
THROUGH EARLY NEXT WEEKEND GIVEN GOOD OVERALL AGREEMENT AND
MAINTAINS CONSISTENCY WITH THE PRIOR FORECAST. THE BLEND FOR THE
LATTER PART OF THE PERIOD USED THE 00Z ECMWF/06Z GFS AND THE 00Z
ECENS/06Z GEFS MEANS AS DIFFERENCES NATURALLY BEGIN TO INCREASE,
AND THE CMC DIVERGES FROM THE OTHER GUIDANCE WITH A MORE AGGRESSIVE
DEPICTION OF A SHORT-WAVE BREAKING THROUGH THE BROAD UPPER-RIDGING
OVER THE CENTRAL U.S.
..WEATHER/HAZARDS HIGHLIGHTS
FOR THURSDAY AND FRIDAY, THERE ARE THREE AREAS WITH MARGINAL RISKS
FOR EXCESSIVE RAINFALL/FLASH FLOODING -- THE UPPER MIDWEST, MID-
SOUTH/SOUTHEAST, AND SOUTHWEST. THE FIRST IS DUE TO AN APPROACHING
FRONTAL SYSTEM WITH ANOTHER JUST TO THE SOUTH OVER THE PLAINS --
SHOWERS/STORMS ARE LIKELY AHEAD OF THE WARM FRONT. THE STORM
PREDICTION CENTER HAS INDICATED THE THREAT FOR SEVERE WEATHER IN
THE UPPER MIDWEST THIS THURSDAY AS WELL. THE SECOND AREA IS DUE TO
INCREASED MOISTURE IN THE SOUTHEAST 1/4 OF THE CONUS, COINCIDENT
WITH DAYTIME HEATING WHICH WILL SPARK MAINLY AFTERNOON
SHOWERS/STORMS. THE LAST AREA (SOUTHWEST) WILL SEE AN INCREASE IN
MOISTURE INTO THE REGION OUT OF MEXICO THURSDAY WITH A NUDGE
EASTWARD FRIDAY. POTENTIAL EXISTS FOR FUTURE UPGRADES TO SLIGHT
RISKS IN EACH OF THESE AREAS, BUT CONFIDENCE IS LIMITED AT THIS
RANGE. INTO THE WEEKEND AND NEXT MONDAY, RAINFALL MAY EASE A BIT IN
THE SOUTHWEST BUT INCREASE OVER THE UPPER MIDWEST/GREAT LAKES AND
EVENTUALLY NORTHEAST AS THE COLD FRONT MOVES EASTWARD. THE
SOUTHEAST WILL CONTINUE TO SEE A DAILY CHANCE OF SHOWERS/STORMS IN
TYPICAL SUMMERTIME FASHION.
TEMPERATURES WILL BE VERY WARM/HOT OVER THE PLAINS THURSDAY
(APPROACHING 100F) WHICH WILL SPREAD EASTWARD INTO THE WEEKEND,
REACHING THE MIDWEST FRIDAY AND THE NORTHEAST/MID-ATLANTIC THIS
COMING WEEKEND. MANY AREAS WILL SEE TEMPERATURES INTO THE 90S WITH
HIGHER HUMIDITY. THIS WILL DRIVE HEATRISK VALUES INTO THE THE
MODERATE (LEVEL 2) TO PERHAPS MAJOR (LEVEL 3 OUT OF 4) CATEGORY.
HIGH TEMPERATURES AND HUMIDITY WILL COMBINE TO MAKE FOR VERY
UNCOMFORTABLE CONDITIONS AS WELL OVER FLORIDA LATE THIS WEEK AND
AND ALONG THE GULF COAST INTO THE WEEKEND AS AN INTENSIFYING UPPER-
LEVEL HIGH PASSES OVERHEAD. OVER THE PACIFIC NORTHWEST INTO
CALIFORNIA, TEMPERATURES WILL BE COOLER THAN NORMAL AS TROUGHING
DIGS INTO THE WEST. COASTAL AREAS MAY ONLY SEE HIGHS INTO THE 60S
AND LOW 70S WITH INLAND AREAS ONLY IN THE 80S TO LOW 90S. ABUNDANT
CLOUD COVER WITH ELEVATED RAIN CHANCES OVER THE SOUTHWEST WILL
LIKELY KEEP TEMPERATURES COOLER THAN NORMAL AS WELL
-- 90S TO LOW 100S FOR THE DESERT CITIES.
PUTNAM/FRACASSO
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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