664 
FXUS63 KMPX 062357
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
657 PM CDT Wed Oct 6 2021

.SHORT TERM...(This evening through Thursday night)
Issued at 252 PM CDT Wed Oct 6 2021

The stratus deck that moved up from the southeast this morning is 
narrowing and where the sun has been able to come out CU fields have 
developed. The NBM was pretty aggressive in reducing cloud cover 
overnight, so in coordination with neighboring offices we bumped up 
the cloud coverage overnight. An upper low will move north out of 
the Arkansas/Missouri area, more or less tracking along the 
Mississippi River, and advect deeper moisture into our forecast 
area. This will bring the chance for isolated to scattered showers 
tomorrow. Reduced the PoPs a bit for tomorrow as the NBM PoPs looked 
overdone. Rainfall totals look to be quite light with only a few 
hundredths, to perhaps a tenth of an inch. The best chance for any 
showers will be in eastern Minnesota and west central Wisconsin. 
There is some CAPE in the forecast, so some thunder is possible, 
particularly in southern Minnesota. Clouds overnight should keep the 
threat of fog pretty minimal. The chance for showers will continue 
into Thursday evening before winding down overnight as the upper low 
gets caught up in the southwest flow aloft and begins tracking more 
to the northeast.

Not much change in temperatures through the short term. Highs 
tomorrow will be mainly in the low to mid 70s with the warmest 
temperatures in western Minnesota. Lows tonight will fall into the 
50s, to around 60 in the Metro area, with clouds increasing. Low 
temperatures tomorrow night will be similar, perhaps a degree or two 

.LONG TERM...(Friday through Wednesday)
Issued at 252 PM CDT Wed Oct 6 2021

The already above normal temperatures are forecast to climb even 
more Friday into Saturday as a thermal ridge builds into the Central 
Plains from the southwest. Highs Friday and Saturday are forecast in 
the mid to upper 70s, with a chance of isolated 80s. In fact, the 
deterministic ECWMF and GFS show MSP reaching 80 at least one day to 
end the week. Lows Friday and Saturday night will be in the mid to 
upper 50s, with the Twin Cities heat island remaining slightly 
warmer. Showers are possible across our eastern CWA Friday afternoon 
as a weak, cutoff low over the Mississippi River Valley slowly 
meanders northward. This disturbance will eventually make its way 
into the Great Lakes before getting caught up in the upper-level 
flow and traveling east.

Meanwhile, our next good chance of precip looks to be Saturday into 
Sunday as a vorticity maximum associated with a positively tilted 
trough over CA/NV breaks off and travels northeast into the Northern 
Plains. A strong, 140 knot southwesterly jetstreak ahead of the 
vorticity max should allow for a deepening surface low, moving from 
the Dakotas across northern MN into Sunday night. Guidance favors 
the heaviest area of precip along the northern periphery of the low 
near the warm front and deformation zone. To the south, the moisture 
profile in the low to mid-levels is drier causing models to be more 
stingy with rain. As such, NBM has likely to definite PoPs across 
northern MN, decreasing to chance then slight chance PoPs as one 
goes south to southern MN. QPF amounts follow the same regime with 
perhaps our northern MN counties nearing an inch total for the 
weekend. Guidance does hint multiple inches across northwest MN; an 
area that desperately needs rain.

Heading into early next week, models amplify a vast upper-level 
ridge across eastern North America in response to strong low-level 
WAA. The placement and strength of this ridge should act to steer 
any future systems northward as they enter the central CONUS. 
Indeed, another chance of rain is possible across the Upper Midwest 
Monday into Monday night as the remainder of the aforementioned 
CA/NV trough finally ejects east of the Rockies. Following this 
system is when things could get really interesting. A strong upper-
level jetstreak is forecast to dive south along the west coast 
Monday, highly amplifying a trough over the western CONUS by Monday 
night. Long range models show this trough crossing the Rockies and 
ejecting northeast into the Northern Plains by mid-next week. While 
timing and placement uncertainty exists, ensembles and deterministic 
guidance seem to agree that there will be a strong low and surface 
cyclone affecting some part of the north-central CONUS Wednesday 
into Thursday. Thus, our first strong low pressure system for the 
Fall season could be on the horizon. Temperatures for next week are 
forecast to cool but still remain slightly above normal for early to 
mid October (normal highs are in the lower 60s while lows are in the 
lower 40s.)

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 657 PM CDT Wed Oct 6 2021

The biggest issue this period surrounds around MVFR stratus 
timing/extent on Thursday. Trends for precip are on a downward 
direction for the day on Thursday, but increasing Thursday evening 
(after this period for all but MSP). For the stratus, favored the 
more conservative GFS for bringing it in and how far northwest to 
take it. This did delay when MN terminals see the stratus and we 
introduced it into WI as well. RAP/HRRR are a bit more aggressive 
with the stratus for both bringing it in earlier and spreading it 
across all MPX terminals, so continued modifications to the cig 
forecast are likely.

KMSP...RAP shows stratus moving into MSP as early as 11z and quite a
bit lower (IFR) than the GFS. However, with the sub-VFR stratus
currently just a narrow east-west band of MVFR cigs from the Quad 
Cities to Chicago, not confident enough in the RAP to go that 
aggressive yet.

/OUTLOOK FOR KMSP/
Fri...VFR. Wind S 5-10 kts. 
Sat...VFR. Chc MVFR/-SHRA. Wind SE 15G25 kts.
Sun...VFR. Chc MVFR/-SHRA. Wind W 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&

$$

SHORT TERM...CEO
LONG TERM...CTG
AVIATION...MPG