112
FXUS02 KWBC 270758
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
358 AM EDT WED AUG 27 2025
VALID 12Z SAT AUG 30 2025 - 12Z WED SEP 03 2025
..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 PLAINS THIS WEEKEND. HEAVY RAIN POTENTIAL
WILL ALSO EXIST ACROSS THE SOUTHERN U.S. AS A SLOW-MOVING FRONTAL
BOUNDARY SINKS INTO THE NORTHERN GULF THROUGH EARLY NEXT WEEK.
A DIGGING UPPER TROUGH IN THE EASTERN PACIFIC MAY INCREASE MONSOON
ACTIVITY ACROSS THE FOUR CORNERS NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
A NON-DETERMINISTIC CANADIAN BLEND SUFFICIENTLY CAPTURED THE
OVERALL SYNOPTIC EVOLUTION ACROSS THE LOWER 48 DURING THE MEDIUM
RANGE PERIOD. HEAVY WEIGHTING WAS PLACED ON THE DETERMINISTIC EURO
AND GFS THIS WEEKEND SINCE THEY RESOLVE THE LARGE SCALE FEATURES
SIMILARLY WELL. THE EURO HAS A MORE AMPLIFIED SHORTWAVE PROPAGATING
THROUGH THE WESTERN RIDGE ON SUNDAY WHILE, THE GFS HAS A MORE
PROGRESSIVE SHORTWAVE CUTTING THROUGH THE NORTHERN PLAINS/UPPER
MIDWEST.
THE ENSEMBLE MEANS MAKE UP A MAJORITY OF THE BLEND BEGINNING ON
DAY 5 AND CONTINUING THROUGH THE END OF THE PERIOD. ON DAY 5,
THE EURO SUITE IS MORE SUPPRESSED THAN THE GFS AND CANADIAN SUITES,
WHICH CLUSTER WELL TOGETHER, WITH QPF OVER THE SOUTHERN HIGH
PLAINS/SOUTHWEST.
..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 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 AND SUNDAY. ON SATURDAY, THERE IS AN EMBEDDED SLIGHT RISK
OF EXCESSIVE RAINFALL FOR PARTS OF THE TEXAS/OKLAHOMA PANHANDLES
AND EASTERN NEW MEXICO, WHERE PRIMED SURFACES CAUSED BY STORMS ON
FRIDAY COULD RESULT IN SCATTERED INSTANCES OF FLASH FLOODING. A
SLIGHT RISK WAS INTRODUCED OVER SOUTHERN NEW MEXICO INTO FAR
WESTERN TEXAS ON SUNDAY, DUE TO AN INCREASING QPF TREND IN THE
LATEST GUIDANCE OVER THOSE AREAS. THE CURRENT SLIGHT REMAINS CLOSE
TO THE BORDER ZONES BUT COULD EXPAND NORTH IF RECENT TRENDS IN THE
GFS AND CANADIAN CONTINUE.
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
MAY 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.
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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