textproduct: Billings

KEY MESSAGES

- A chance for a mix of rain/snow late tonight into Tuesday morning, highest probabilities 40 to 70% in the Pryor/Bighorn mountains and adjacent foothills/plains. There is a slight chance (10-20%) for a short period of freezing rain mixed in over portions of SE Montana (Miles City/Baker/Ekalaka) around sunrise.

- Mostly dry and very warm with periods of gusty winds along the western foothills through the next 7 days.

- Increased grass fire concerns across the area this week.

UPDATE

Updated forecast for the latest model trends through tomorrow. Models continue to trend wetter with a shortwave crossing the area late tonight into tomorrow morning. Temperature/Dew Point spreads narrow considerably before midnight over northeast zones. Added a mention of patchy fog to these areas until precipitation chances increase just before sunrise.

Increased precipitation chances 10 to 20 percent across central and eastern zones during this period to account for this trend. Precipitation will be a mix of rain/snow with a slight chance for a brief period of freezing rain mixed in over northeast zones from Miles City to Baker and Ekalaka. At this point precipitation chances in this wintry mixed precipitation area are 30 percent or lower and the very short latency before temperatures warm up turning precipitation to plain rain should keep impacts very low. Area with the best chance for precipitation tonight will be the north and east slopes of the Pryor and Bighorn mountains into the adjacent plains. Precipitation chances in this area are in the 40 to 70 percent range. Snow levels drop to around 4500 feet with a mix of rain/snow down to 3500 feet. Snow accumulations look to be a dusting to an inch over the lower foothills, with up to 3 inches in the Bighorn and Pryor mountains. Mid shift will keep an eye on this and issue additional messaging if needed.

Tweaked winds up a bit over the western foothills (Livingston/Nye) to account for stronger pressure gradient overnight along and ahead of the approaching shortwave. Gusts in the 40s to around 50 mph seem reasonable from late evening through sunrise. Chambers

AVIATION

00z Forecast Discussion...

Winds are diminishing with sunset and the development of a surface inversion. By late this evening an approaching shortwave will stir up the winds along the western foothills with gusts in the 25 to 40kt range west of Billings, strongest in the Livingston/Big Timber/Nye vicinity. Further east the surface inversion should hold surface winds down but LLWS probabilities increase with 30 to 40kts around 2kft AGL.

Patchy fog with local MVFR conditions is possible from around midnight through sunrise, or when the shortwave trof arrives, for areas east of Forsyth into the Dakotas. This includes KMLS/KBHK/K1S3 terminals.

As the shortwave arrives precipitation chances increase along with low cloud cover. Precipitation chances will be mainly east of Billings and highest in the southern foothills around Sheridan (KSHR). Precipitation will be mainly a mix of rain/snow, however a slight chance (10-20%) of freezing rain is in the forecast over northeast zones from Miles City to Baker for a few hours around sunrise. Once the shortwave moves through temperatures will quickly rise ending the wintry mixed precipitation chances. Local MVFR to IFR conditions are possible near precipitation areas, with the poorest conditions along the Pryor/Bighorn mountains and adjacent foothills/plains. Chambers

PRELIMINARY POINT TEMP/POPS

Tue Wed Thu Fri Sat Sun Mon ----------------------------------------------------------- BIL 036/053 030/058 039/065 032/059 034/060 037/060 035/054 22/R 00/B 00/U 00/U 00/U 01/B 23/W LVM 035/049 031/057 035/061 034/060 033/056 035/055 032/048 21/N 00/B 00/U 00/U 00/U 01/B 33/W HDN 031/053 024/061 035/067 026/059 031/059 031/062 032/056 44/R 00/B 00/U 00/U 00/U 01/B 23/W MLS 029/048 024/054 036/062 026/053 030/053 030/057 032/051 23/O 00/B 00/U 00/U 00/U 00/B 11/B 4BQ 031/047 025/055 038/064 030/057 032/055 030/059 032/053 24/O 00/B 00/U 00/U 00/U 00/B 12/W BHK 024/043 022/049 033/056 026/049 025/050 027/053 027/047 03/O 00/B 00/U 00/U 00/B 00/B 11/B SHR 026/047 024/057 033/065 029/060 030/058 030/060 029/051 45/O 00/B 00/U 00/U 00/U 00/B 23/W

BYZ WATCHES/WARNINGS/ADVISORIES

MT...None. WY...None.