Area Forecast Discussion
Issued by NWS Dodge City, KS
Issued by NWS Dodge City, KS
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149 FXUS63 KDDC 181926 AFDDDC Area Forecast Discussion National Weather Service Dodge City KS 226 PM CDT Tue Jun 18 2024 .KEY MESSAGES... - Rain and thunderstorms are expected Tuesday afternoon through Wednesday. Some storms will produce severe wind and hail, and some locally very heavy rainfall is expected. Some flooding issues are possible through Wednesday morning, with a Flash Flood Watch in effect. - Much cooler behind a cold front on Wednesday, with temperatures in the 60s and 70s through the day. && .UPDATE... Issued at 153 PM CDT Tue Jun 18 2024 MESOSCALE DISCUSSION... A cold front was beginning to stall across southwest Kansas. Convection was already developing along the boundary early this afternoon. 0-6 km bulk shear values were marginally supportive of supercell structures. However, shear will be stronger on the cool side of the boundary and dewpoints/CAPE values will be high. There may be a brief window through 6 pm or so when tornadoes and very large hail are possible with any isolated supercell that is located on the cool side of the boundary. Additionally, landspout tornadoes are possible for storms anchored along the front given the steepening low to mid level lapse rates. During the evening hours, expect convection to form into a line, with marginally severe hail and damaging wind the main concern. Given the high moisture content and possibility of training storms, flash flooding is possible for areas that experience multiple storms. && .DISCUSSION... Issued at 200 PM CDT Tue Jun 18 2024 Midday surface observations depicted an unusually strong cold front for mid June standards, slowing its forward progress from the northwest zones into NW KS. Ahead of the cold front, strong south winds continued, gusting 40-45 mph. Strong moisture convergence along the advancing boundary is expected to result in explosive thunderstorm development along a roughly Hays- Dodge City-Liberal line starting around 4 pm. Strong instability and moderate wind shear, combined with the strong surface boundary providing a source of low level vorticity, will result in some supercell structures for the first few hours of the event, roughly 4-7 pm. Large hail and tornadic/landspout potential is expected from this activity, especially where 1) storms can remain discrete longer, and 2) surface winds retain a backed easterly component. Hatched probability for significant hail > 2 inches and significant wind gusts > 75 mph was maintained on the 1630z outlook, and with an increase in tornado probability along that preferred HYS-DDC-LBL line 4-7 pm. Moisture content is high, with dewpoints near or above 70, resulting in low LCLs and very efficient heavy rainfall production. Very rare to have such a glaring flash flood potential/risk this far west in SW KS. During the course of the evening, and through tonight and sunrise Wednesday, a mesoscale convective complex (MCS) will evolve over SW KS, along and north of the slowly moving frontal boundary. Threat during the evening will rapidly transition from hail/wind/tornadoes, to widespread heavy rainfall toward midnight. In fact, areas of heavy rainfall are expected through the night, and the inherited flash flood watch is warranted and well placed. Expanded the flash flood watch southward to include Haskell, Meade and Clark counties. QPF of 1-2 inches is expected to be common, especially along and south of US 50, with 2-4 inches typical where training becomes established. Some CAM solutions are printing out some crazy rainfall totals through tonight; one should not place much emphasis on these exact forecast amounts and locations. Rather, the message is clear: locally intense, flooding rainfall is expected tonight through Wednesday morning, with hydrologic concerns. Needless to say, heavy rain wording was included in the grids and forecast products. Residents are reminded to avoid driving through water of unknown depth, especially tonight after sunset. Additional rain and thunderstorms will regenerate through at least the first half of Wednesday, as forcing for ascent continues above the slowly advancing cold front. All models also generate widespread low stratus, with east/northeast winds establishing in the saturated boundary layer. Between unseasonably strong cold advection, and the stratus, Wednesday will be much cooler; the question is how much cooler. For example, 12z MET/NAM guidance keeps GCK and the northwest zones in the 50s all day Wednesday. GFS solutions show a more modest cooling, with a reduction of about 5C at 850 mb. Reduced afternoon temperatures to the lower to mid 70s for many zones, but suspect many will hold in the 60s. A warming trend is expected Thursday through Saturday, as temperatures quickly rebound in the strongest sunshine of the year. Standing water and saturated topsoils from tonight`s rain will slow this process down significantly. Still, mid 90s are expected to be common by Saturday afternoon. 12z GEFS ensemble members show a 30% probability of temperatures > 100 across the favored Red Hills southeast of DDC Saturday afternoon. It stands to reason that rain chances will also dwindle away during this time window. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1123 AM CDT Tue Jun 18 2024 VFR will continue through the next several hours, with strong south winds persisting, gusting to near 40 kts. Midday surface observations showed a strong cold front draped across NW KS, and this boundary will make progress further into SW KS this afternoon. 12z ARW shows thunderstorms developing along this cold front along a HYS-DDC-LBL line 21z-00z, and used this timing as a guide in this set of TAFs. With the frontal boundary becoming stationary for the remainder of the TAF period, periods of rain, showers or thunderstorms will prevail through 18z Wed, with reduced flight categories in locally heavy rainfall likely. TAFs already include convective TEMPO groups for at least initial development, but additional TEMPOs/amendments are likely through the TAF period. Model consensus is for IFR stratus to fill in behind the cold front/MCS through Wednesday morning, with high confidence of degraded flight conditions through this period. && .DDC WATCHES/WARNINGS/ADVISORIES... Flood Watch from 7 PM CDT this evening through Wednesday evening for KSZ030-031-043>046-063>066-076>080-087-088. && $$ MESOSCALE DISCUSSION...Finch DISCUSSION...Turner AVIATION...Turner