911
FXUS02 KWBC 271905
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
305 PM EDT WED AUG 27 2025
VALID 12Z SAT AUG 30 2025 - 12Z WED SEP 03 2025
...HEAVY RAIN AND FLASH FLOOD POTENTIAL IN PORTIONS OF TEXAS AND
NEW MEXICO THIS WEEKEND...
..OVERVIEW
MEAN TROUGHING OVER THE EAST IS EXPECTED TO PERSIST THROUGH THE
MEDIUM RANGE PERIOD WITH BLOCKY RIDGING OVER THE INTERIOR WEST.
WEAK DISTURBANCES SLIDING DOWN THE WESTERN SIDE OF THE UPPER TROUGH
WILL INTERACT WITH A STATIONARY SURFACE FRONT TO GENERATE HEAVY
RAIN THREATS ACROSS THE NORTHERN AND CENTRAL PLAINS THIS WEEKEND.
HEAVY RAIN POTENTIAL WILL ALSO EXIST ACROSS THE SOUTHERN TIER AS A
SLOW-MOVING FRONTAL BOUNDARY SINKS INTO THE NORTHERN GULF THROUGH
EARLY NEXT WEEK. UPPER LEVEL ENERGY CUTTING THROUGH THE RIDGE OVER
THE INTERIOR WEST WILL LIKELY PROVIDE ADDITIONAL SUPPORT FOR HEAVY
RAIN AND FLASH FLOODING OVER TEXAS AND NEW MEXICO THIS WEEKEND.
NEXT WEEK, A DIGGING UPPER TROUGH IN THE EASTERN PACIFIC MAY
INCREASE MONSOON ACTIVITY ACROSS THE FOUR CORNERS REGION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE PATTERN
THROUGH THE WEEKEND, THEN AGREEMENT DECREASES NEXT WEEK AS MODELS
STRUGGLE TO DETERMINE INTERACTIONS BETWEEN PACIFIC TROUGHING AND
DOWNSTREAM RIDGING. AGREEMENT DOES REMAIN HIGH ON THE EASTERN
PATTERN WITH ALL AVAILABLE DETERMINISTIC MODELS SHOWING A STRONG
TROUGH DROPPING INTO THE NORTH-CENTRAL U.S. MID-NEXT WEEK.
FOR WPC'S AFTERNOON FORECAST, A BLEND OF THE DETERMINISTIC
GFS/ECMWF/CMC/UKMET WAS USED FOR DAYS 3 AND 4 (SATURDAY AND
SUNDAY), WITH MORE WEIGHT ON THE GFS AND ECMWF THAN THE CMC AND
UKMET. OVERALL, THE GFS AND ECMWF ARE IN GOOD AGREEMENT AND SEEM TO
CAPTURE THE PATTERN WELL WHILE THE CMC AND UKMET TEND TO FALL ON
THE PERIPHERY OF THE GENERAL CONSENSUS. FROM DAY 5 ONWARDS,
ENSEMBLE MEANS FROM THE CMCE/ECENS/GEFS WERE ADDED IN INCREASING
AMOUNTS AND THE CMC/UKMET WERE PHASED OUT. THIS PRODUCED A GOOD
MIDDLE OF THE ROAD SOLUTION THAT SMOOTHS OUT DIFFERENCES AMONG THE
DETERMINISTIC MODELS.
..WEATHER/HAZARDS HIGHLIGHTS
A STATIONARY FRONT OVER THE HIGH PLAINS AND A SLOW-MOVING COLD
FRONT ACROSS THE GULF COAST STATES WILL BE THE FOCUS FOR SHOWERS
AND THUNDERSTORMS LATE THIS WEEK. SUFFICIENT MOISTURE AND FAVORABLE
UPPER LEVEL DYNAMICS ALONG THESE BOUNDARIES WILL SUPPORT HEAVY
RAIN THREATS IN THESE REGIONS. THERE IS A BROAD MARGINAL RISK OF
EXCESSIVE RAINFALL FROM THE GREAT PLAINS DOWN AND ACROSS THE GULF
COAST STATES AND SOUTHEAST ON SATURDAY, WITH AN EMBEDDED SLIGHT
RISK AREA OVER THE TEXAS PANHANDLE AND EASTERN NEW MEXICO. WITHIN
THE SLIGHT RISK AREA, SOILS WILL BE PRIMED BY HEAVY RAIN FROM
STORMS ON FRIDAY, AND ADDITIONAL STORMS COULD RESULT IN SCATTERED
INSTANCES OF FLASH FLOODING.
ON SUNDAY, THERE IS ANOTHER BROAD MARGINAL RISK OF EXCESSIVE
RAINFALL ACROSS THE SOUTHERN TIER FROM EASTERN ARIZONA TO THE
SOUTHEAST COAST. UPPER LEVEL ENERGY CUTTING THROUGH THE UPPER RIDGE
WILL LIKELY PROVIDE INCREASED SUPPORT FOR HEAVY RAIN OVER THE
SOUTHWEST ON SUNDAY, SO THERE IS AN EMBEDDED SLIGHT RISK OF
EXCESSIVE RAINFALL FOR PARTS OF SOUTHERN NEW MEXICO AND FAR WEST
TEXAS. QPF TRENDS HAVE CONTINUED TO INCREASE IN THIS REGION TODAY,
LEADING TO A SMALL NORTHWARD EXPANSION FROM THE OVERNIGHT OUTLOOK.
HEAVY RAIN POTENTIAL WILL ALSO EXIST FOR PORTIONS OF THE
CENTRAL/NORTHERN PLAINS AND MIDWEST ON SUNDAY IN THE VICINITY OF A
SURFACE LOW PRESSURE SYSTEM, LEADING TO A MARGINAL RISK OF
EXCESSIVE RAINFALL FOR THIS AREA.
ELSEWHERE, THE DOWNSTREAM SECTION OF THE FRONT WILL PRODUCE
ADDITIONAL THUNDERSTORM ACTIVITY ACROSS THE GULF COAST THIS
WEEKEND. A CONVERGENCE AXIS BENEATH A WEAK DISTURBANCE ALOFT COULD
REFOCUS MONSOON MOISTURE OVER MUCH OF NEW MEXICO AND THE FOUR
CORNERS REGION LATER THIS WEEKEND AND INTO NEXT WEEK. SHOWERS AND
STORMS WILL LIKELY ALSO RETURN TO THE NORTHERN TIER NEXT WEEK AS A
COLD FRONT SINKS SOUTH ACROSS THE NORTHERN ROCKIES, PLAINS, AND
UPPER MIDWEST. THERE MAY BE POTENTIAL FOR ISOLATED HEAVY RAIN
THREATS WITH THIS FRONT, THOUGH IT IS VERY UNCERTAIN AT THIS TIME.
SURFACE HIGH PRESSURE FROM CANADA WILL DESCEND OVER MUCH OF THE
EASTERN U.S. BEGINNING THIS WEEKEND. THIS WILL BRING A COOL AND
DRY CONTINENTAL AIRMASS TO THE MIDWEST AND EAST COAST, MAKING FOR
A VERY COMFORTABLE LABOR DAY WEEKEND. CLOUDY AND STORMY CONDITIONS
OVER THE PLAINS WILL LIKELY CONTRIBUTE TO WELL BELOW AVERAGE
TEMPERATURES THIS WEEKEND. COLDER AIR WILL ALSO FILTER INTO THE
NORTH-CENTRAL U.S. MID-NEXT WEEK IN THE WAKE OF A COLD FRONT.
DOLAN/KEBEDE
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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