Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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666 FXUS65 KCYS 012325 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 525 PM MDT Sat Jun 1 2024 .KEY MESSAGES... - A few strong to severe thunderstorms are expected late this afternoon through the early evening hours, mainly from far southeast Wyoming into the western Nebraska Panhandle. Large hail and damaging winds will be the primary hazards, although an isolated tornado cannot be entirely ruled out. - Numerous showers and thunderstorms are expected across all of southeast Wyoming and the western Nebraska Panhandle on Sunday. Strong to locally damaging wind gusts will be the main convective hazard, mainly from late morning through late afternoon. && .SHORT TERM /THROUGH MONDAY/... Issued at 220 PM MDT Sat Jun 1 2024 A few strong to severe thunderstorms will likely impact portions of far southeast Wyoming and the western Nebraska Panhandle over the next few hours, aided by modest upper-level support ahead of a weak short wave disturbance and moisture convergence along the surface dryline. Convective coverage should remain limited given the modest forcing, but the main focus area should be across the southern Nebraska Panhandle in the zone of weakest CIN and over- all best low-level convergence. Dew points in the low to mid 50s and steepening lapse rates are supporting MLCAPEs near 1500-2000 J/kg, while 40+ knots of 500-mb flow contributes to strong deep- layer effective vertical shear of 35+ knots. As such, any storms that develop will have the potential to become supercells w/ the potential for large hail & damaging winds. Significant hail risk will depend on whether storms can remain discrete, but expect to see some additional development in the next few hours which will have potential to disturb the inflow. An active day is expected for Sunday beneath fast, active quasi- zonal flow aloft. This mid-level energy will interact with a 700 millibar warm front, giving way to numerous showers and thunder- storms by mid/late morning. Ample jet energy, coupled with shear vectors oriented parallel to the warm frontal zone would suggest potential for organized linear and bowing line segments, capable of strong/damaging wind gusts in excess of 60 MPH with localized potential for 75+ MPH, especially over the southern Panhandle as a more organized MCS starts to become established to the east in the deeper moisture. The latest SLGT/ENH risks from SPC are just east of the CWA, but would not be surprised to see this nudged W in future updates if high-res guidance continues to suggest this type of storm mode. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 220 PM MDT Sat Jun 1 2024 Minimal changes made to the long term forecast. Still looks mostly dry with a windier period possible through mid-next week and warmer temperatures for the end of the week. Both the ECMWF and the GFS show a shortwave trough moving across the CWA late Monday night into Tuesday. With this trough, comes a cool front, which will lead to cooler, but still mild temperatures on Tuesday. Aside from cooler temperatures, this front will also bring breezy to windy conditions across much of the CWA, with the potential for high winds for the usual southeast Wyoming wind prone areas. Behind the front, strong westerlies will exist with 700 mb winds between 50 and 60 kts over the Laramie Range and Arlington area. A decent MSLP gradient will exist west of the Laramie Range with good subsidence. This could bring some stronger winds down to the surface and lead to high winds over Arlington and the South Laramie Range on Tuesday. Continued elevated to high winds could continue into Wednesday with strong westerlies. Even in-house guidance shows 50 percent and greater probabilities for high winds at Arlington and the South Laramie Range. By Thursday, upper-level ridging begins to build over western CONUS, leading to quiet, dry and warming temperatures through the end of the work week. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 518 PM MDT Sat Jun 1 2024 Showers and thunderstorms will be moving through the area this evening. Temporary VIS reductions are anticipated where -TSRA occurs directly over terminals. This will bring MVFR/IFR to KAIA and KBFF through approximately 2Z this evening before trending back to VFR. Remaining terminals will experience VFR this evening and overnight. Occasional gusty winds can be expected where VCTS/TSRA is present up to 25-35+ knots for short durations. Another round of strong to severe weather is possible for terminals on Sunday, primarily along and east of I-25 after 16Z Sunday. Please see individual TAFs for further information. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CLH LONG TERM...SF AVIATION...BW