NWS Forecast Discussion

Below is the latest Area Forecast Discussion from the Twin Cities National Weather Service office in Chanhassen, MN. It gives insight into why the forecasters are making the predictions you read in your local forecast. The overall "big picture" of the atmospheric setup is well described, as well as the forecasters' interpretation of the various Computer Atmospheric Models (CAMs). Sometimes, very specific information is available here that is not available, or otherwise generalized, in the public forecast.

Forecast Discussion for MPX NWS Office
000
FXUS63 KMPX 190843
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
343 AM CDT Tue Mar 19 2024

.KEY MESSAGES...

- Elevated fire weather conditions persist through Wednesday,
  continuing into Thursday for eastern MN & western WI.

- Accumulating snow coming Thursday evening (western MN) into
  Thursday night (eastern MN and western WI)

- Potential for a more significant winter storm continues to
  exist for Sunday through Tuesday next week.

&&

.DISCUSSION...
Issued at 342 AM CDT Tue Mar 19 2024

Overnight temperatures have been mild with the thermal ridge passing
overhead. Most sites are in the mid to upper 30s with southwest
winds gusting up to 25 mph. The timing of the thermal ridge is not
ideal as we`ll see cold air advection ramp up after sunrise and
persist through the day. Surface temperatures will still rebound
into the low to mid 40s with a chance at 50 along I-90 corridor.
Unfortunately for us gusty northwest winds will make it feel similar
to this past weekend so dress accordingly. Speaking of the wind
situation today, sustained winds 20 to 25 mph with sporadic gusts up
to 40 mph will remain just below wind advisory criteria. That also
means we`ll see yet another day with elevated fire weather
conditions across Minnesota and western Wisconsin when adding in low
RH values & the brown remnants of last year`s vegetation. A
secondary cold front comes through tonight with a reinforcing
shot of cold air. This will be another dry airmass with our RHs
dropping into the mid 20 percent range, but the winds should
decrease to keep us at elevated fire weather conditions. Highs
will be in the mid to upper 30s on Wednesday.

For Thursday and Friday, our next system has continued to slow down
in forecast guidance, but it remains likely that we`ll see a swath
of accumulating snow across Minnesota and Wisconsin by Friday AM.
The heaviest snow now looks to fall Thursday late afternoon into
Thursday night for western MN and Thursday night into Friday AM for
eastern MN and western WI. The synoptic scale set up is still
supportive of seeing a broad area of light precip, with a strong
northwest to southeast oriented thermal gradient aloft across MN/WI
within the right entrance region of an upper jet streak. The
widespread light precipitation will be driven by large scale
isentropic upglide, but there remains a strong signal for a FGEN
induced band of heavier snow that`ll track through southern MN.
Another concern is with potential convection over Iowa and along the
I-80 corridor. Recent guidance suggests that feature may limit
moisture advection and forcing further north, but similar features
existed with the Valentines day system, which had a similar set up
aloft. We`ll have to keep an eye on the potential convection and
when hi-res (CAMS) come into range as a confidence booster for this
system`s QPF/Snow forecast. Current forecast continues to highlight
a broad area of 2 to 4 inches of snow along the I-94 and I-90
corridors in MN & WI, with a narrower swath of 4 to 7" possible
within the broader area. It`s also possible we`ll see an initial
FGEN band that tracks along the I-94 corridor before another one
develops further south driven by the potential convection. This
could lead to locally heavier amounts across places like S and
SE MN. Thankfully winds will be manageable and the potential
for blowing snow concerns appears low for now.

For this weekend & into early next week, the focus will shift back
to our west. A trough will dig into the Rockies, which will lead to
an active stretch of weather through Tuesday or Wednesday of next
week. Guidance has continued to bounce around with what the exact
evolution of this period will be, but guidance has remained
consistent in highlighting several waves traveling through the deep
western trough. This is important as it helps increase our
confidence that we`ll likely see some type of impacts from these
waves as they eject into the central Plains. The most interesting
one for our area is the first wave to eject out on Sunday. This
system will bring an initial burst of heavier FGEN/WAA precipitation
on Sunday. Current trends suggest this will be mostly snow,
highlighting the potential for several inches of accumulation across
southern Minnesota and into western Wisconsin. The second wave
ejects Tuesday and takes on a strong negative tilt as it tracks into
the upper Mississippi Valley or western Great Lakes region. If it`s
further east, precipitation chances will likely trend lower, but if
it stays further west it could lead to an additional round of
precipitation. This system will be potent and very dynamic as it
wraps a TROWAL back into the sfc low as it moves northeast on
Tuesday. This would likely lead to a period of either rain or wintry
mix where ever this feature tracks. Current guidance has begun to
trend a bit further east of our area which makes sense given the
first wave impacting us directly. There is still a great deal of
uncertainty with both systems for the weekend & early next week but
it`s looking increasingly likely that more significant winter
weather will impact the region this weekend. &&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1244 AM CDT Tue Mar 19 2024

Skies will remain clear for the first several hours of the
period before a SCT-BKN mid-level deck moves in from the
northwest. VFR conditions are favored throughout the period, but
we`ll have to keep an eye on a stratocu deck to our north &
east. Southwesterly winds at 10-15 knots tonight, with a period
of LLWS through 08-10z. It will generally be westerly between
40-50 knots. Later this morning, winds will become turn
northwesterly and increase in speed with sustained values of
15-20 knots and gusts 25 to 30 knots.


KMSP...Have kept LLWS from 06-08Z tonight with a west-southwesterly
direction near 45 knots. VFR cigs now appear favored as MVFR
cigs remain off to the north/east of MSP. Winds will shift from
SW to W to NW by sunrise with gusts up to 30kts likely.


/OUTLOOK FOR KMSP/
WED...VFR. Winds NW 15G25kts.
THU...MVFR/-SN likely. Wind E 5-10 kts.
FRI...IFR/-SN likely. VFR in afternoon. Wind N 5-10 kts.

&&

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

&&

$$

DISCUSSION...BPH
AVIATION...BPH

NWS MPX Office Area Forecast Discussion