828
FXUS65 KGGW 112119
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
319 PM MDT Thu Jul 11 2024

.DISCUSSION...


KEY MESSAGES:

+++ AFTERNOON PACKAGE UPDATE: Most of this morning`s forecast
discussion remains valid. No changes were made to the Heat
Advisories issued. Given the NAM Nest and NSSL great description
of this morning`s showers and thunderstorms, gave greater
confidence in their output for this afternoon, which show an
isolated thunderstorm off the lee of the Little Rockies (and areas
nearby). Wind gust guidance from these CAMS show gusts associated
with the outflow boundaries gusting between 40-60 mph, with
isolated gusts as high 70 mph range. This generally remains a
threat through about 8pm. +++

1) Hot and mostly dry weather is expected through the weekend,
with the hottest temperatures expected today. Heat Advisory is in
effect for all of NE Montana through 9 PM and the southern zones
for Friday.

2) Isolated thunderstorms are possible at times through the
weekend. A few storms could become severe with damaging winds.


WEATHER PATTERN OVERVIEW:

Upper ridge will remain in place in varying degrees for the next
several days. Today will have the hottest temperatures with highs
between 95 and 105 and Heat Advisory in effect for all areas.
Wind speeds will remain light so despite the very low humidity,
conditions will remain below Red Flag criteria. For areas south of
the Missouri River along with Southern Valley and Roosevelt
Counties, the heat advisory has been extended to include Friday as
highs in these areas will be near 100.

The ridge gets flattened somewhat this evening and northeast
Montana will be on the periphery of the ridge through weekend.
Weak waves moving across the top of the ridge will allow for some
high based thunderstorms at times with strong and erratic winds.

A weakening cold front comes through NE Montana during the day on
Friday with chances for thunderstorms. It will lower temperatures
a few degrees for the weekend with highs mainly in the 90s.

FORECAST CONFIDENCE & DEVIATIONS:

Confidence is high that temperatures will be in the 90s most areas
through the weekend with many locations seeing highs of 100-105
today. Low confidence on timing any thunderstorms that are
expected today and continuing through the weekend.

-Enriquez



&&

.AVIATION...
LAST UPDATE: 2115Z

FLIGHT CAT RANGE: VFR

DISCUSSION: While it will be clear to partly cloudy with a few mid
and high clouds through tonight, there will also be isolated
showers and thunderstorms at times which could produce strong and
erratic wind gusts.

DENSITY ALTITUDE will be a problem today when temperatures are
above 100 degrees.

WIND: Becoming light and variable late tonight. Outflow
boundaries from any thunderstorms that occur will create gusty and
erratic winds. Friday, winds become more northwesterly, increasing
throughout the day to 10-15 kts.


&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM MDT this evening for Central and
Southeast Phillips-Daniels-Northern Phillips-Northern Valley-
Sheridan-Southwest Phillips.

Heat Advisory until 9 PM MDT Friday for Central and Southern
Valley-Dawson-Eastern Roosevelt-Garfield-McCone-Petroleum-
Prairie-Richland-Western Roosevelt-Wibaux.

&&

$$

weather.gov/glasgow