Area Forecast Discussion
Issued by NWS Dodge City, KS
Issued by NWS Dodge City, KS
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082 FXUS63 KDDC 250918 AFDDDC Area Forecast Discussion National Weather Service Dodge City KS 418 AM CDT Tue Jun 25 2024 .KEY MESSAGES... - Heat Advisory remains in effect for this afternoon for forecast heat index values of 103 to 107 degrees. An isolated location or two, particularly across Red Hills region, may approach 110F heat index for a brief time. - Another round of scattered thunderstorms tonight, but the main activity will likely be southeast of much of our forecast area. - A cold front late tonight will mark the beginning of an active stretch of nightly thunderstorms rolling east across western Kansas, mainly at night. Signals continue to be quite strong for widespread 1 to 2 inches of total rainfall between Wednesday Night and Sunday. && .DISCUSSION... Issued at 415 AM CDT Tue Jun 25 2024 The overnight water vapor imagery and RAP analysis showed a continued split jet pattern in the upper troposphere with the main branch at its typical summer latitude near the Canada border. The secondary, weaker, yet still important jet farther south extended from northern Nevada east across the Colorado Rockies. RAP analysis had an enhanced jetlet centered across central Colorado with left exit region across west central Kansas. This is likely the main forcing mechanism for ascent to promote the continued generation of scattered showers and thunderstorms through the night between Highway 50 and I-70. The 00Z HREF had a fairly good handle on this overnight activity as it maintained 10km neighborhood probability of 30-40% for 25+ dBZ composite reflectivity. The 00Z HREF does show these probabilities lowering quite a bit toward sunrise, and the POP grids will reflect this forecast weakening of overnight convection. As we head in to the afternoon Tuesday, all the models show this southern branch of the jet shifting northward into Wyoming, yet keeping west central and northwest Kansas in a favorable exit region for upward vertical motion to support another round of thunderstorms. The increasing low level thicknesses due to rising overall heights across the Southern Rockies will support another hot afternoon. In fact, 850mb temperatures will be slightly warmer, thus a larger area will likely see highs in the 101 to 104F range. Models are also showing a relative minimum signal in afternoon highs east/northeast of Dodge City, and the HREF does show this signal, but even if temperatures do not reach 100 degrees in portions of the eastern CWA, dewpoints are likely to hold in the 64 to 67F range to keep resulting heat indices in the 104 to 107F range. No changes are going to be made to the counties that are currently in the Heat Advisory for this afternoon. Using HREF 10km neighborhood probabilities as a proxy for where/when best thunderstorm activity will be later this afternoon, signals are strongest across northern/northwestern Oklahoma where probabilities of 25+ dBZ composite reflectivity exceed 35% across much of the northern half of Oklahoma. A secondary signal is shown later in the afternoon/early evening across our northern/northwestern counties in vicinity of a weak surface vorticity center, but the convective signal is not nearly as strong as farther southeast, so the uncertainty is greater. Going forward, all the models still show a fairly strong cold front by summer standards later on tonight into Wednesday. This will put a temporary break on excessive heat indices (except for one more day of very hot heat indices possible across the Red Hills). This front will actually mark the beginning of a rather prolonged wet pattern for western/central Kansas (and much of the Central Plains for that matter). Post frontal moist upslope will develop by Wednesday Night, focusing thunderstorm development across eastern Colorado. The first of several nights of formidable mesoscale convective systems (MCS) will likely move out across western Kansas Wednesday Night. An ensemble approach is still the best forecast method for best run-to- run continuity. The 00Z run of the 100-member Grand Ensemble continues to show around 0.8" 50th percentile for Dodge City (and much of the rest of our southwest Kansas region, for that matter). 90th percentile QPF through the end of the month are nearly 2 inches. Given multiple chances for much of the area to see heavy rainfall over a roughly 4-night period, it is very reasonable to think that upper end potential (1-in-10 chance) of 2-3" of rainfall is certainly not out of the question. As it stands of this forecast, there is really not one night out of the 4 (Wednesday Night through Saturday Night) that is favored over any other at this point, and there is going to be a feedback from previous night MCS that will have ramifications on the next day`s forecast that simply cannot be predicted on a sub-synoptic scale. Regardless, the synoptic pattern characterized by a summer ridge that is flattened out and south of our area will continue to favor MCS activity in vicinity of the Southwest Kansas region through the end of the month. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1214 AM CDT Tue Jun 25 2024 A small mesoscale convective system (MCS) was moving across the HYS terminal at the onset of this new TAF period, but we will initialize HYS with vicinity showers as the thunderstorms will be moving south of the terminal at the beginning of the period. Elsewhere, the probability of thunderstorm impact at any of the other three terminals DDC, GCK, LBL is too low to include in overnight TAF. That said, latest satellite and radar trends were showing an uptick in convection across far west central KS, which if holds together and forms into another small MCS, amendments at GCK and/or DDC will be needed overnight. Another round of scattered thunderstorms will be possible late day/evening Tuesday, but signals from latest models are all over the place with respect to timing/location of storms, so until there is a greater convective signal to latch on to with respect to individual terminal impact, we will not insert thunderstorms later in the day on this synoptic TAF cycle. && .DDC WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening for KSZ030-031-045-046-064>066-077>081-086>090. && $$ DISCUSSION...Umscheid AVIATION...Umscheid