987
FXUS02 KWBC 080652
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 AM EDT FRI AUG 8 2025
VALID 12Z MON AUG 11 2025 - 12Z FRI AUG 15 2025
..HEAT RETURNS TO THE MIDWEST/GREAT LAKES/NORTHEAST NEXT WEEK
..OVERVIEW
CENTRAL CONUS TROUGHING WILL YIELD TO STRONG DOWNSTREAM RIDGING
OVER SOUTHEASTERN CANADA THAT WILL HELP USHER IN MUCH WARMER
TEMPERATURES TO THE NORTHEAST 1/4 OF THE LOWER 48. STRONG UPPER
RIDGING OVER THE NORTHEASTERN PACIFIC IS FORECAST TO RETROGRADE,
ALLOWING DIGGING TROUGHING TO SETTLE INTO THE PACIFIC NORTHWEST.
COOLER THAN NORMAL TEMPERATURES WILL REPLACE THE WARMER THAN NORMAL
TEMPERATURES BY LATER IN THE WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST 12Z/18Z GUIDANCE SHOWED REASONABLE AGREEMENT ON THE
UPPER LEVEL PATTERN THROUGH THE PERIOD, EXCEPT FOR THE NORTHEASTERN
PACIFIC INTO THE NORTHWEST. THERE, THE MODELS (DYNAMICAL AND
AI/ML) HAVE BEEN INCONSISTENT AND SPLIT ON HOW TO HANDLE SHORTWAVES
RIDGING UP AND OVER THE RIDGE. HOWEVER, THE 12Z DETERMINISTIC
MODELS WERE DEEPER/SLOWER THAN THE ENSEMBLES GENERALLY SHOWED
(EXCEPT THE GFS WHERE THE 18Z WAS BETTER CLUSTERED WITH THE OTHER
12Z GUIDANCE). IN ADDITION, THE ECMWF AIFS ENSEMBLE WAS SLOWER THAN
ITS DYNAMICAL COUNTERPART, LENDING CREDENCE TO THE SLOWER
DETERMINSTIC-LED SOLUTION. THUS, UTILIZED A SUPER MAJORITY BLEND OF
THE DETERMINISTIC GUIDANCE THROUGH NEXT THURSDAY BUT WITH LIMITED
CONFIDENCE (AS EVEN THE AI MODELS HAVE WAVERED IN THEIR FORECASTS).
ALONG/EAST OF THE DIVIDE, THE BROADER CONSENSUS WAS A SUFFICIENT
STARTING POINT.
..WEATHER/HAZARDS HIGHLIGHTS
A COLD FRONT OVER THE GREAT LAKES (ON MONDAY) BACK TO THE PLAINS
WILL BE A FOCUS FOR SOME LOCALLY HEAVY RAIN MONDAY INTO TUESDAY AS
IT SLOWLY PUSHES TO THE EAST AND SOUTHEAST INTO THE MIDWEST. TO THE
SOUTH, A LINGERING STATIONARY BOUNDARY DRAPED ALONG THE I-10
CORRIDOR AMID HIGHER THAN NORMAL MOISTURE LEVELS WILL ALSO ACT AS
AN IMPETUS FOR SOME HEAVIER RAIN. BOTH OF THESE AREAS, FOR MONDAY
AND TUESDAY, ARE DENOTED WITH A MARGINAL RISK OF FLASH FLOODING
(EXCESSIVE RAINFALL). IN ADDITION, MUCH OF NEW MEXICO AND INTO
SOUTHEASTERN ARIZONA MAY SEE SOME LOCALIZED MODEST RAINFALL AMID
SENSITIVE TERRAIN. A MARGINAL RISK EXISTS THERE FOR MONDAY. FOR THE
REST OF THE WEEK, RAINFALL CHANCES WILL INCREASE OVER THE EASTERN
1/3 OF THE COUNTRY AS THE NORTHERN FRONTAL BOUNDARY WAVERS OVER THE
REGION.
TEMPERATURES WILL WARM INTO THE NORTHEAST TO NEAR RECORD LEVELS
MON-WED WITH HIGHS INTO THE 90S. THIS WILL PUSH HEATRISK LEVELS
INTO THE MODERATE (LEVEL 2) TO MAJOR (LEVEL 3 OUT OF 4) CATEGORY
AFTER A RELATIVELY COOL/COMFORTABLE START TO AUGUST. LINGERING HEAT
OVER THE SOUTHWEST WILL SLOWLY SUBSIDE THROUGH THE PERIOD THOUGH
TEMPERATURES WILL REMAIN SLIGHTLY ABOVE NORMAL.
ON THE FLIP SIDE, INCREASED TROUGHING INTO THE PACIFIC NORTHWEST
WILL COOL TEMPERATURES RATHER SMARTLY FROM 5-15 DEGREES ABOVE
NORMAL MONDAY TO 5-10 DEGREES BELOW NORMAL BY THURSDAY (WA/OR). TO
THE SOUTH THROUGH COASTAL CA, TEMPERATURES WILL HOVER NEAR TO BELOW
NORMAL AS THE COOLER THAN NORMAL SUMMER CARRIES ON.
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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