907 
FXUS63 KMPX 271115
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
615 AM CDT Sun Mar 27 2022

.UPDATE...
Issued at 612 AM CDT Sun Mar 27 2022

Updated for 12z aviation discussion.

&&

.DISCUSSION...(Today through Saturday)
Issued at 343 AM CDT Sun Mar 27 2022

- Critically low RH values Sunday and Monday afternoon.

- Large storm system Tuesday-Thursday. Heavy rain, accumulating 
  snow, and a wintry mix of freezing rain and sleet are all possible 
  at times

It's a chilly start to the morning with persistent north winds
overnight allowing for temperatures to drop into the single digits 
across central Minnesota and into the teens elsewhere. Another bright
and sunny day is expected, but temperatures will remain cold with 
high pressure centered overhead. Highs will only reach into the low 
to mid 30s. Despite the cold temperatures, very dry air under the 
high will allow for relative humidity values to drop into the teens 
across much of the area this afternoon. A few values in the single 
digits are possible across central Minnesota and west-central 
Wisconsin, which is more desert-like than Upper Midwest. Critical 
fire weather conditions will not be met despite the low RH values, 
as winds will be light with the center of the high overhead. Caution 
should still be used if doing any outdoor burning today. Another cool
night is expected as winds remain light overnight with clear skies. 
Lows in the single digits are possible again across portions central 
Minnesota and west-central Wisconsin, with temepratures in the teens
to low 20s elsewhere.

Southeasterly winds pick up on Monday as the high pressure begins to
depart to the east. Temperatures will be warmer as warm advection
increases through the day; highs in the upper 30s to mid 40s are
expected. Another day of critically low RH values looks likely as
values could again drop into the teens, primarily north and east of 
I-94. Winds are expected to be lighter where the RH values are
lowest, generally around 10-15 mph. Meanwhile wind gusts of 20-30 
mph are likely to develop across western and southern Minnesota, but
increasing moisture through the day means RH values will likely only
drop to around 30%.

There remains uncertainty on the evolution of the storm system 
moving out of the Rockies and into the plains on Wednesday. This 
will have major impacts on the associated surface features and 
precipitation amounts. 

Due to both a northern and southern jet stream and associated 
shortwaves embedded in these jets, global models are having trouble 
phasing these two together. Eventually, the embedded shortwaves will 
merge into one large storm system across the Great Lakes by 
Thursday. 

During the phasing period, models are trying to develop two areas of 
low pressure across the plains. First, and once the northern 
shortwave moves out of the northern Rockies, a surface low will 
develop with precipitation rapidly developing along and north of 
this feature. Initially, temperatures will be cold enough to warrant 
a concern of freezing rain across the north/northeast CWA (Mainly 
north of I-94 and east of I-35). NBM probabilities of receiving 
>0.01" of freezing rain is around 70-90 percent during the 24-hour 
time period from Tuesday evening through Wednesday evening for 
portions of west-central Wi, and east-central Mn. However, these 
probabilities diminish to less than 50 percent for anything more 
than 0.05". The greater potential of minor or moderate impacts of 
ice accumulation will occur across northern and eastern Wisconsin. 
The secondary shortwave moving out of the southern Rockies Tuesday 
will lead to another area of low pressure in the central/southern 
plains. This is where a line of severe storms will likely develop 
and will play a role on the northern surface low orientation and 
strength. Eventually, one storm system will develop somewhere across 
the Midwest/Great Lakes region Wednesday night. Due to differences 
in the global models and how the main surface low develops, 
confidence on where a band of measurable snowfall will develop once 
colder air arrives, is low. Consensus of the models and the overall 
mean suggest that eastern Mn/western Wi has the best probability of 
receiving a few inches of snow late Wednesday night, and into 
Thursday. Probabilities diminish farther to the west as the spread 
in the ensembles increase. The 500-hPa heights and anomalies from 
the global models suggest that the trend for the storm system is to 
limit the amount of precipitation across the Dakotas vs several 
model runs ago past Wednesday morning. 

For those concern on impacts of this storm system, please be aware 
of the uncertainties as this system is still hundredths of miles 
west of the west coast of the CONUS. Once this storm moves onshore 
and begins to interact with the Rockies and moisture from the Gulf 
of Mexico, will our region have a better idea of the strength, 
location and impacts of this developing system.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 612 AM CDT Sun Mar 27 2022

VFR conditions through the period. Clear skies through today with
mid-level clouds increasing overnight. Northerly winds of 5-10 kts 
through sunset, with winds becoming light and more easterly 
overnight.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/
MON PM...VFR. Wind SE 10-15 kts. 
TUE...AM VFR. MVFR/-RA likely PM. Wind SE 20G30 kts. 
WED...IFR/-RA likely with -SN possible late. Wind NE 10-15 kts bcmg 
NW 15G25 late.

&&

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

$$

DISCUSSION...ETA/JLT
AVIATION...ETA