textproduct: Great Falls

KEY MESSAGES

- High Wind Warning in effect for the Northern Rocky Mountain Front and adjacent plains from this evening through Saturday morning. - Small potential for freezing rain in Blaine County Tonight. - High potential for 60+ degrees on Sunday, Wednesday, Thursday, and next Friday.

DISCUSSION

- Meteorological Overview:

Strong and persistent upper level ridging will be the main driver of our weather over the next week or so, bringing generally warm, dry, and occasionally breezy weather to the area. While this ridge will be the predominant pattern, we will have a few weak systems moving through the area over the northern edge of this ridge, the first of which will move through the area overnight tonight, bringing increased winds and some light precipitation, some of which may fall as freezing rain in Blaine County. Winds will also be on the increase behind this light round of precipitation (see the Confidence & Scenarios section for more details on the precipitation and winds).

These winds will blow in some noticeably warmer air for Saturday and especially Sunday, with temperatures climbing into the upper 50s and even low 60s both days. A weak weather system will bring some cooler air Monday and Tuesday, but warmth quickly builds back into the area, with many lower elevation areas reaching the 60s each afternoon for the second half of the week.

- Forecast Confidence & Scenarios:

Wintry Precipitation tonight: A round of isolated to scattered light precipitation will accompany an elevated warm front pushing through the area this evening. While temperatures at the surface should generally be above freezing at lower elevations, a few areas of northeastern Blaine County may be a bit slow to get above freezing tonight. Should temperatures be slow to rise and some of the isolated precipitation makes its way into the area, a light glaze of ice will be possible. Be cautious even if temperatures rise just slightly above freezing, as ground temperatures may still be cold enough to allow some of the rain to freeze on contact even if your thermometer is reading above freezing.

Winds tonight through Saturday: Winds will be on the increase overnight tonight behind an initial round of scattered light precipitation, first along the Rocky Mountain Front tonight, then across the plains during the day on Saturday. This event has been on the fence of High Wind Criteria in a few locations, which prompted the issuance of the High Wind Watch yesterday. Now that the time for upgrade decisions has arrived, I remain on the fence with this event as probabilities for High Wind criteria generally remain around or under 50%. With that said, this falls short of the 80% confidence suggested for an upgrade to a warning, so I have elected to drop most of the High Wind Watches at this time. That excludes the Northern High Plains and Glacier Park region, as I have just enough confidence for high winds to occur here to warrant the upgrade to the Warning. Regardless of whether or not a specific area received the upgrade, tonight and tomorrow morning will be quite gusty, so the watch did its job of getting our message out. Ludwig

AVIATION

30/18Z TAF Period

VFR conditions will prevail across all terminals during this TAF Period. From now through 31/10Z there is a 10 - 30% chance for rain or snow at all terminals. During this TAF period winds will increase at the KCTB terminal to gust in excess of 40 kts for several hours in the middle of this TAF Period. There will be isolated instances of low-level wind shear and mountain wave turbulence primarily across North-central Montana during this TAF Period. For the first few hours of this TAF Period there will be mountain obscuration across Southwestern Montana. -IG

PRELIMINARY POINT TEMPS/POPS

GTF 41 57 35 56 / 10 0 0 0 CTB 38 54 32 55 / 10 0 0 0 HLN 35 54 30 51 / 10 0 0 0 BZN 29 53 27 52 / 10 0 0 0 WYS 16 37 10 39 / 10 0 0 0 DLN 27 50 27 51 / 0 0 0 0 HVR 35 51 25 49 / 10 0 0 0 LWT 36 52 30 56 / 20 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning from 8 PM this evening to 11 AM MST Saturday for East Glacier Park Region-Northern High Plains.