####018004890####
FXUS65 KGGW 041252

AFDGGW



Area Forecast Discussion

National Weather Service Glasgow MT

652 AM MDT Sat May 4 2024



.DISCUSSION...

KEY MESSAGES:



- Unusually warm conditions are expected on Sunday. Southeast

  winds will be quite strong, with gusts into the 40s in some 

  places.



- Another round of rain is expected starting Sunday night through

  at least Thursday. Ranges are looking on track to be around a

  inch and a half to 2 inches for many locations with above

  average confidence(60-80%).



- The first high wind signal is starting to show up Monday

  night/Tuesday across the Southwest. With diurnal timing being

  poor, will hold off on issuing a High Wind Watch yet. Low

  confidence(15-30%)



WEATHER PATTERN OVERVIEW:

Synoptic Setup: Forecast begins with a trough running down from

Manitoba into the Dakotas. A closed low is moving on shore of the

Pacific Northwest and northern California with a ridge formed up

between these two features running from the Four Corners through

the Western Montana and into Alberta. 



Today through Sunday: There will be a cold start to this morning 

with some places pulling out of the 20s for lows. Expect a 

warming trend of 10 to 15 degrees each day as the ridge to the 

west moves through the region. The ridge looks like it is going to

tap into Desert Southwest air which will make it unusually warm 

for the region by Sunday with 70s and perhaps brief 80s for highs.

This is about 15 to 20 degrees above normal in some locations. 

Meanwhile, the closed low from the PCNW will push itself into the 

ridge, positioning itself over the Intermountain West while 

stretching into a very amplified negative tilted trough in 

response to the ridge.



Sunday night through Monday: A southern flow interface will setup

between the extremely warm temps of the exiting ridge and the 

incoming trough over the Intermountain West. This will start 

pulling gulf moisture into the Great Plains potentially all the 

way up toward eastern Montana. The intense cool down will generate

a closed low over south central Montana with enough lift energy 

to not only generate rain showers but also thunderstorms across 

the region through these periods. Already small chances for any 

severe TS have diminished further and thunderstorms look like 

they have become mostly elevated. A signal for a northward moving 

baroclinic leaf(50-70%) looks to be forming across the eastern CWA

which would increase rainfall totals Monday afternoon with any

convection.



Monday night through Thursday night: Closed low will migrate 

northeastward and start to cut off/occlude from the warm air. 

However, this just means that most of the convective elements will

become mainly stratiform. Main problem here onward is that 

positioning of the surface low is still in question with a range 

for its center position stretch anywhere from western South 

Dakota all the way up to southern Saskatchewan. 



Pressure gradient forces behind the low look to set up enough wind

to possibly(15-30% chance) lead up to a High Wind event Monday

night/Tuesday morning. Tonight's forecast was the first signal 

from the NBM for this and the position of the low along with poor 

night time diurnal coupling could easily scrub this event.



The low also still looks to generate a trowal in most models

starting mid-day Tuesday through Wednesday which will bring a 

heavy amount of rain to areas directly under or behind it. The 

majority of the ensembles place this over central to eastern 

Montana which could easily generate 1 to 2 inches to the area it 

hits. This feature has remained consistent over the last 72 hours 

raising confidence to above average(60-80%).



Friday onward: A new ridge looks to move into the area which will

raise temps and dry conditions out through the weekend. GAH





&&



.AVIATION...



LAST UPDATED: 1030Z 



FLIGHT CAT RANGE: VFR



DISCUSSION: Clouds will diminish this morning with a deck hanging 

on just northeast of KOLF-KSDY. This afternoon will feature 

mainly clear skies with increasing high to mid clouds tonight. 



LLWS: Some low level wind shear will be possible (20-50% chance) 

across northeast Montana from 07-14Z tonight, but it looks to 

only impact KSDY and/or KGDV for a couple hours at this time.



WIND: Light and variable through the morning. Becoming southerly 

at 5 to 10 kts this afternoon. Then veering SE to E and increasing

to 5 to 15 kts this evening through tonight. 



GAH







&&



.GGW WATCHES/WARNINGS/ADVISORIES...

Lake Wind Advisory from midnight tonight to noon MDT Monday for 

Central and Southeast Phillips-Central and Southern Valley-

Garfield-McCone-Petroleum.



&&



$$



weather.gov/glasgow