Area Forecast Discussion
Issued by NWS Dodge City, KS
Issued by NWS Dodge City, KS
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849 FXUS63 KDDC 182200 AFDDDC Area Forecast Discussion National Weather Service Dodge City KS 500 PM CDT Wed Sep 18 2024 ...Updated Aviation... .KEY MESSAGES... - Marginal Risk (Level 1 of 5) of a severe storm or two east of an Ashland to Larned line, however coverage of storms will be much less than last night. - Next major storm system poised for the weekend with increased thunderstorm and rainfall potential. Period of greatest rainfall potential from Saturday afternoon through Sunday morning. - Strong cold front behind weekend storm system will lead to beginning of cooler period with highs in the 70s next week. && .DISCUSSION... Issued at 400 AM CDT Wed Sep 18 2024 A significant precipitation event, which over-performed quite a bit from yesterday`s forecast, continued to push slowly east during the overnight hours. Total rainfall here at NWS DDC was near two inches as of 08Z (3 AM CDT)! The over-performance of this event across southwest Kansas was due largely in part to the exit region of a stronger-than-forecast southern branch jet that nosed squarely toward southwest Kansas. The widespread coverage of heavy rainfall will have a bit of an impact on temperatures this afternoon, and we have pulled back some on afternoon temperatures closer to straight NBM (instead of 75th to 90th percentile), thus highs will likely be upper 80s to around 90 most areas, except for the Red Hills in the mid 90s where less rainfall occurred. A remnant convergence axis in low level winds this afternoon, mainly just east of Dodge City, will likely foster redevelopment of isolated to widely scattered thunderstorms. The Day One SPC Outlook does have a Marginal Risk (1 of 5) for this activity, however overall forcing for ascent will be much weaker today other than the boundary layer convergence. After this afternoon/early evening`s isolated thunderstorm activity, we will see a break on Thursday in between system, then eyes turn back to the west for our next storm system. Our next storm system over the weekend still looks on track for potential significant precipitation amounts across portions of the Central and High Plains. This event will be focused on late Saturday and Saturday Night, perhaps into early Sunday morning. Global model ensemble systems GEFS, ECMWF EPS, and Canadian GEPS all show a strong QPF signal. Meteorological features supporting heavy rainfall include a slow-moving upper low ejecting northeast out of the Desert Southwest region into Colorado, a moistening lower troposphere as strong southerly winds develop to our south ahead of the system, allowing for development of a mature warm, moist conveyor belt. Model ensemble consensus (100-member Grand Ensemble means) show a 500mb low/vorticity max center tracking from near Flagstaff, AZ Saturday morning to around Denver, CO late Saturday Night. Grand Ensemble mean 850mb height/wind/temperature fields suggest strongest low level frontogenetic forcing from eastern Colorado into northwestern Kansas Saturday Night, which would favor areas just north of our NWS DDC forecast area for widespread 1-2" rainfall. That being said, appreciable thunderstorms and rainfall will also occur within the warm conveyor belt airstream itself across our southwest Kansas region, supporting fairly high probabilities of 0.50" or greater rainfall over a 24-hr period from Saturday afternoon to Sunday afternoon (~25% over the Red Hills region increasing northward to ~60% up across Trego-Ellis County). Over the past couple of runs, the Canadian GEPS ensemble system has been the farthest south of the three main ensemble systems, really focusing heavy precipitation squarely on the northern half of our forecast area between Highway 50 and I-70. The GEPS has 75th percentile 24-hr QPF of 1.25 to 1.75". The other two ensemble systems keep 75th percentile 1.5"+ QPF farther north across far northwest Kansas into southwestern Nebraska. The next forecast challenge will be temperatures once the strong cold front pushes south Sunday morning. Latest Grand Ensemble has 50th percentile afternoon temperatures Sunday in the mid 60s across our northwest counties (Hamilton-Scott) to the lower 80s across the Red Hills. There remains quite a bit of uncertainty still as 25-75th percentile range on the Grand Ensemble is 15 to 18F. Next week, temperatures will be much more on par for late September with highs generally in the mid to upper 70s early to mid next week with lows well down into the 50s, and even upper 40s out west closer to Colorado. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 500 PM CDT Wed Sep 18 2024 Good flying weather will continue through this TAF period, with VFR/SKC at all airports. Any showers and thunderstorms Wednesday evening will stay southeast of all airports. Elevated south winds of 10-15 kts will prevail overnight. Light winds will trend northerly after 15z Thu. && .DDC WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Sugden AVIATION...Turner