591
FXUS02 KWNH 130801
PREEPD
PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 AM EDT WED MAY 13 2026
VALID 12Z SAT MAY 16 2026 - 12Z WED MAY 20 2026
..CENTRAL U.S. HEAVY RAINFALL/RUNOFF AND SEVERE WEATHER THREAT
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE FORECAST CLUSTERING REMAINS GOOD VALID FOR THIS WEEKEND
INTO MONDAY, BOLSTERING CONFIDENCE IN A GFS/ECMWF/UKMET/CANADIAN
MODEL COMPOSITE BLEND THAT SEEMS WELL SUPPORTED BY ENSEMBLES IN
THIS TIMEFRAME. MODEL FORECAST CLUSTERING STEADILY INCREASES
ACROSS LONGER TIME FRAMES AS VARIED UPSTREAM SYSTEMS/ENERGIES WORK
INTO THE WESTERN TO CENTRAL U.S., BUT A GENERALLY MORE COMPATIBLE
GEFS/ECMWF/CANADIAN ENSEMBLE MEANS COMPOSITE SEEMS TO PROVIDE A
DECENT FORECAST BASIS, BUT POSSIBLY NOT QUITE AMPLIFIED ENOUGH
GIVEN GUIDANCE PATTERN TRENDS. THIS HAS BEEN ADJUSTED MANUALLY AND
WPC PRODUCT CONTINUITY IS DECENT DESPITE THESE UNCERTAINTIES.
..WEATHER/HAZARDS HIGHLIGHTS
ENERGETIC UPPER TROUGH/DEEPENED SURFACE LOW EJECTION OVER SOUTH-
CENTRAL THEN EASTERN CANADA WILL LAY DOWN A TRAILING FRONT WITH
FROM THE NORTH-CENTRAL U.S TO THE NORTHEAST. IMPULSES, RIGHT
ENTRANCE REGION UPPER JET LIFT AND MOISTURE/INSTABILITY FOCUS INTO
THE UPPER MIDWEST PORTION OF THIS FRONT MAY SUPPORT EMERGING
CONVECTIVE DEVELOPMENT AND POTENTIAL FOR LOCAL TRAINING HAS
DESPITE DETAIL UNCERTAINTY PROMPTED THE INTRODUCTION OF WPC
EXCESSIVE RAINFALL OUTLOOK MARGINAL RISK AREAS VALID FOR
DAY4/SATURDAY AND DAY 5/SUNDAY.
FARTHER UPSTREAM SYSTEM ENERGIES SUBSEQUENTLY WORK INTO THE WEST
AND DOWNSTREAM UP ACROSS THE CENTRAL U.S. WITH LESS CERTAINTY THIS
WEEKEND INTO NEXT WEEK IN AMPLIFYING FLOW. PASSAGE MAY YIELD
ENHANCED WEEKEND WINDS AND WILDFIRE THREAT POTENTIAL ACROSS THE
SOUTHERN ROCKIES/HIGH PLAINS. THERE IS ALSO THEN AN INCREASING
SIGNAL THAT PLAINS CYCLOGENESIS/FRONTOGENESIS, UPPER JET SUPPORT
AND GROWING LEAD GULF RETURN FLOW MAY FURTHER SET THE STAGE TO
FUEL AN EXPANDING CENTRAL U.S. CONVECTIVE RAINFALL/RUNOFF AND
SEVERE WEATHER THREAT PATTERN TO MONITOR AS INDICATED BY SPC.
MEANWHILE, AN EASTWARD SPREADING UPPER RIDGE WILL SPREAD WELL
ABOVE NORMAL PRE-FRONTAL TEMPERATURES ACROSS THE CENTRAL TO EASTERN
U.S. DOWNSTREAM THIS PERIOD THAT MAY SUPPORT SOME LOCAL HIGH
TEMPERATURE VALUES. TO THE SOUTH, LOW LEVEL ONSHORE FLOW WILL BRING
SHOWER INTO FLORIDA IN PROXIMITY TO UPPER LOW DEVELOPMENT
NEAR/EAST OF THE BAHAMAS.
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES ARE AT:
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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