909
FXUS02 KWBC 051752
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 PM EDT FRI SEP 5 2025
VALID 12Z MON SEP 08 2025 - 12Z FRI SEP 12 2025
..OVERVIEW
THE FLOW PATTERN FOR NEXT WEEK SHOULD REMAIN OVERALL AMPLIFIED AND
SLOW TO DISLODGE WITH A ROCKIES TO PLAINS RIDGE SANDWICHED BETWEEN
WEST COAST AND EAST COAST TROUGHS. IN THIS PATTERN, WAVY FRONTAL
SYSTEMS WILL FOCUS MOST RAIN CHANCES OVER THE NORTHWEST/WEST AND
SLOWLY OUT TO THE ROCKIES/PLAINS AND ALSO DOWNSTREAM OVER THE UPPER
MIDWEST/GREAT LAKES WITH NORTHERN STREAM ENERGY, FROM SOUTH TEXAS
AND THE GULF AND ESPECIALLY ACROSS FLORIDA, AND AN AXIS ALONG/JUST
OFF THE COASTAL SOUTHEAST/CAROLINAS WITH MOIST SOUTHERN STREAM
FLOW.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GFS/ECMWF/UKMET AND CANADIAN MODEL SOLUTIONS CONTINUE TO BE
GENERALLY WELL CLUSTERED FOR EARLY/MID NEXT WEEK AND A FAVORED
COMPOSITE BLEND IS WELL SUPPORTED BY ENSEMBLES AND MACHINE LEARNING
GUIDANCE IN A PATTERN WITH OVERALL ABOVE NORMAL PREDICTABILITY.
FOR LATER IN THE WEEK, THERE IS A LOT OF UNCERTAINTY WITH ENERGY
AND SHORTWAVES THROUGH THE LARGER WESTERN U.S. TROUGH, AND HOW MUCH
ENERGY EJECTS EASTWARD INTO THE NORTHERN PLAINS. THEREFORE, THE
WPC BLEND FOR THE LATTER HALF OF THE WEEK CONSISTS OF A GREATER
WEIGHTING TOWARDS THE ENSEMBLE MEANS TO HELP SMOOTH OUT THE RUN TO
RUN VARIANCES. THIS APPROACH MAINTAINS GOOD CONTINUITY WITH THE
PREVIOUS WPC FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
MONSOONAL RAINFALL AMOUNTS SHOULD GENERALLY DECREASE BY MONDAY,
BUT SOME LINGERING MOISTURE/INSTABILITY FUELING SHOWERS ARE STILL
POSSIBLE. SHOWERS AND STORMS COULD REACH INTO MUCH OF THE PLAINS TO
UPPER MIDWEST CONSISTENT WITH A REGION OF MODEST INSTABILITY NEAR
ANOTHER FRONT. NOT EXPECTING THIS ACTIVITY TO BE MUCH OF A CONCERN
FOR FLASH FLOODING AT THIS TIME SO NO WPC EXCESSIVE RAINFALL
OUTLOOK RISK AREAS ARE DEPICTED FOR DAY 4/5 MONDAY/TUESDAY, BUT
CENTRAL U.S. CONVECTION COULD CONTINUE AS NEXT WEEK PROGRESSES TO
MONITOR.
FARTHER EAST, THE FRONTAL SYSTEM OVER FLORIDA INTO THE WESTERN
ATLANTIC WILL PROVIDE A FOCUS FOR MOISTURE TO POOL, LEADING TO AT
LEAST SCATTERED DIURNAL CONVECTION EACH DAY. MOISTURE LEVELS LOOK
TO DECREASE SLIGHTLY OVER FLORIDA COMPARED TO THE SHORT RANGE
PERIOD, BUT THE SATURATED GROUNDS FROM RAINFALL BEFORE SUNDAY
WARRANT THE ADDITION OF A MARGINAL RISK AREA FOR MONDAY FROM
ROUGHLY CAPE CANAVERAL TO SOUTH FLORIDA. RAINFALL ACROSS THE
CAROLINAS INTO GEORGIA IS RATHER UNCERTAIN WITH HOW MUCH CONVECTION
MAY OCCUR ONSHORE OR OFFSHORE ON ANY GIVEN DAY. SMALL SHIFTS IN
THE FRONTAL BOUNDARY COULD PRODUCE SIGNIFICANT DIFFERENCES IN THE
RAINFALL AMOUNTS, BUT THE AMPLIFIED/SLOWER PATTERN TRANSLATION MAY
ALLOW FOR SOME ONSHORE NUDGE.
AN UPPER LOW PUSHING THROUGH THE EASTERN PACIFIC TOWARD THE
NORTHWEST WILL PRODUCE MULTIPLE DAYS OF RAINFALL NEXT WEEK,
EXPANDING EASTWARD WITH TIME FROM THE PACIFIC NORTHWEST/NORTHERN
CALIFORNIA INTO THE NORTHERN GREAT BASIN AND INTERMOUNTAIN WEST.
THIS COOL SEASON TYPE OF RAINFALL SHOULD BE MARKED BY MODERATE
RATES THAT ARE GENERALLY NOT ENOUGH TO CAUSE FLOODING CONCERNS. THE
LOWERING HEIGHTS ALOFT YIELDING COOLER TEMPERATURES COULD PRODUCE
SNOW FOR THE HIGHEST ELEVATIONS.
SANTORELLI/SCHICHTEL
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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