878 
FXUS63 KFGF 020903
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
403 AM CDT Thu Sep 2 2021

.SHORT TERM...(Today through Friday)
Issued at 307 AM CDT Thu Sep 2 2021

Forecast challenges will be extent of heavy rain and any impacts
from that. Lead short wave moving into NW MN at 08z and on leading
of very moist 850 mb airmass moving in from the south. A narrow
zone of showers and t-storms will continue to develop from NW MN
into SE ND generally in a zone from east of Thief River Falls to
just north of Valley City. Radar estimates show a few small
pockets of 1 inch rainfall thru 08z. Heavy rain cores remain small
however. HRRR did actually pick up on this, esp the 04z run.  

Main 500 mb short wave moivng northeast from central SD at 12z
Thu into NW MN at 00z Fri. PWATS increase to near 2 inches as
moisture. So what has been messaged the past 2-3 days still
looks good in that areas of heavier rainfall (2+ inches) will be
observed within the larger rain area. Some embedded t-storms as
well but no severe wx. Of interest though is closer to the sfc
boundary in western into north central ND and western Manitoba.
Most CAMs indicate scattered t-storms developing near it in a zone
of 500 j/kg CAPE today and moving east and is the main player in
rainfall for the Devils Lake basin, which otherwise misses most of
the rain from this 500 mb system moving in. Excessive Rainfall
Outlook and probabilities of 2+ inches from NBM and WPC all
highlight areas of west central MN, SE ND into northeastern SD
today. This has been the case for the past few days so good
continuity in this regard.  

Rain area starts to move east this evening and overnight, exiting
the far eastern fcst area toward 12z Fri.  


.LONG TERM...(Friday night through Wednesday)
Issued at 307 AM CDT Thu Sep 2 2021

Hazardous weather is not expected within the long term period. 
Upper low within the heart of Canada and attendant upper troughing
in the Pac NW is expected to traverse and dig into the Great 
Lakes/ON/QB region as upper ridging presently in the Midwest to 
Hudson Bay flattens and retrogrades. With the passing of this 
upper trough, there may be some passing shower activity mainly 
confined to central MN and LOW area, however much drier air 
underneath the trough will prevent more widespread precip. Sunday 
appears to be a favored day for this scattered showery activity as
the upper low in Canada nears its closest approach to the FA. 

This trough and drier air will also keep temps mild and comfortable 
with highs in the 60s and 70s this holiday weekend. The exception 
lies perhaps on Monday where shortwave ridging and subsequent warm 
low/mid temps moves into the Northern Plains from the 
west/northwest. NBM shows this warmth through probabilities between 
20-40% of temps over 80s, mainly within North Dakota and the Red 
River valley.

Getting into Tue/Wed timeframe, ensemble guidance begins to diverge 
some in synoptic layout as there is some variation in how the upper 
ridging builds into the western CONUS. Some guidance amplifies the 
overall pattern strengthening this upper ridge. This would favor 
more of an influence from this upper ridge into the area with warmer 
temps into the 70s and 80s and drier weather. Other guidance depicts 
a flatter regime with continued upper troughing in near the Great 
Lakes influencing the area's weather, which would keep temps milder 
and perhaps continue precip chances. The current forecast favors the 
latter at the moment as given by NBM.



&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1117 PM CDT Wed Sep 1 2021

Pretty much stuck with the same timing as the 00z TAFs. There may
be isolated storms overnight, but the steadier rain should hold
off until closer to Thursday morning at KFAR, then spreading
northeast through the day. Ceilings and visibilities will lower
once the steady rain or storms move in. Once the steadier rain
moves in, it looks like it will rain for the remainder of the TAF
period. Ceilings and visibilities will likely bounce around a bit
in the steady rain, but stuck with MVFR/IFR conditions.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$

SHORT TERM...Riddle
LONG TERM...CJ
AVIATION...Godon