textproduct: Glasgow

KEY MESSAGES

- Areas of fog will be present across northeast Montana through Friday morning.

- Warm and dry conditions will persist though Monday.

- Pattern chance to cooler and wetter conditions expected mid-week

DISCUSSION

Today through Friday: Current fog and low stratus sits north and east of a line from about Wibaux to Wolf Point to Malta late this morning and is expected to clear/breakup slightly through the afternoon from SW to NE. However, model data is highly suggestive that once sun goes down the low stratus line will fill back in and progress southwest again. There are a couple locations that indicate 1/4 mile for an hour or two such as Daniels, Sheridan, and central Phillips county and other higher elevation location's, but this does not appear to be widespread or long lasting enough in the data sets to warrant a dense fog advisory... YET. And confidence in placement of quarter mile fog is low, with a lack of CAMs data. Complicating this whole process further tonight is overcast high Chinook arch clouds, which are not modeled by most data sets and will block satellite view of surface coverage of the Fog's extent during this time.

Friday night through Monday: An upper-level ridge over Montana will result in dry conditions and temperatures 10 to 15 degrees above seasonal averages persisting though Monday.

Monday night onward: Model ensembles begin to show discrepancies from monday night onward. However newer runs are beginning to re-phase back into a more SW flow pattern with cooler and potentially wetter weather hear onward.

FORECAST CONFIDENCE & DEVIATIONS:

Significant deviation from hourly NBM for Visibility tonight which was quite pathetic in terms of FOG prediction. Used a blend of RRFS, HRRR, and minimal GLAMP to attempt to improve placement every 3rd hour and interpolated hourly data between every 3rd hour of what data is left after the HRRR dropped out at hour 12-15 for some semblance of reality, now that most CAMs are gone. - Confidence in fair conditions persisting through Monday is high (90%).

DON/GAH

AVIATION

LAST UPDATED: 1730Z.

FLIGHT CAT RANGE: VFR - LIFR

DISCUSSION: As of 17Z low level stratus and FOG has placed itself across the northeastern half of the County warning area. Looking at satellite some breaks arte beginning to appear int eh clouds over teh Yellowstone Valley and KSDY and may clear briefly this afternoon, but the low stratus / fog deck will likely hang in for most places through the afternoon and into tonight. Model data suggests a new round of fog for higher elevations just above the terminals with low stratus remaining in place till 16Z Friday morning.

Confidence in the placement of FOG, and thus visibilities and resultant flight conditions, is still uncertain but better tonight. The forecast has the potential to change up until the last minute. IFR/LIFR conditions have a 30-60% chance of occuring depending on terminal.

WIND: E-SE at 05-15 kts through tonight. Increasint o 10 to 20 kts Friday afternoon.

GGW WATCHES/WARNINGS/ADVISORIES

None.