957
FXUS02 KWBC 140738
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
338 AM EDT THU MAY 14 2026
VALID 12Z SUN MAY 17 2026 - 12Z THU MAY 21 2026
..CENTRAL U.S. HEAVY RAINFALL/RUNOFF AND SEVERE WEATHER THREAT
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE CONTINUES TO SHOW A SIMILAR LARGER SCALE FLOW PATTERN
EVOLUTION OVER OUR FINE NATION IN TRANSITION FROM NEAR ZONAL INTO
THIS WEEKEND TO A MORE AMPLIFIED SOLUTION ALL NEXT WEEK. THERE'S
SIGNIFICANT UNCERTAINTY AS TO THE TIMING AND AMPLITUDE OF CERTAIN
EMBEDDED SHORTWAVES WITHIN THE BROADER DIGGING TROUGH IN THE WEST
NEXT WEEK AND DOWNSTREAM EJECTION. HOWEVER, THERE'S CONSENSUS ON A
BROAD DIFFLUENT PATTERN SETTING UP OVER THE CENTRAL U.S., WHICH
WILL SUPPORT SEVERE STORMS AND HEAVY RAIN POTENTIAL. THERE'S ALSO A
STRONG SIGNAL FOR AN STRONG UPPER RIDGE TO SET UP OVER THE EAST.
THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF GFS/ECMWF/CANADIAN MODELS AND ENSEMBLE MEANS
ALONG WITH THE NATIONAL BLEND OF MODELS IN AN EFFORT TO MITIGATE
SYSTEM VARIANCES AS CONSISTENT WITH INDIVIDUAL PREDICTABILITY. WPC
PRODUCT CONTINUITY IS WELL MAINTAINED IN THIS MANNER.
..WEATHER/HAZARDS HIGHLIGHTS
ENERGETIC UPPER TROUGH/DEEPENED SURFACE LOW EJECTION OVER EASTERN
CANADA WILL LAY DOWN A TRAILING FRONT WITH FROM THE NORTH-CENTRAL
U.S TO THE NORTHEAST THIS WEEKEND. MULTIPLE SHORTWAVE IMPULSE
PASSAGES, FAVORABLE 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 PROMPTED AN WPC EXCESSIVE RAINFALL OUTLOOK
MARGINAL RISK AREAS VALID FOR DAY 4/SUNDAY AND DAY 5/MONDAY, WITH
THE LATTER MORE EXPANSIVE AREA STRETCHING FROM THE UPPER MIDWEST
TO THE SOUTHERN PLAINS FAVORABLE CONVECTIVE PATTERN UPTICK/GROWTH.
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 AMPLE PLAINS CYCLOGENESIS/FRONTOGENESIS, UPPER JET
SUPPORT AND GROWING LEAD GULF RETURN FLOW WILL 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
SHOWERS 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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