National Weather Service Twin Cities Area Forecast Discussion

Data Provided by the National Weather Service

FXUS63 KMPX 171146

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
646 AM CDT Sun Oct 17 2021

.SHORT TERM...(Today through Monday)
Issued at 324 AM CDT Sun Oct 17 2021

We`ll have rising heights until Monday afternoon, when the upper
ridge axis currently over Montana will be centered over MN. Large
scale subsidence will promote mainly clear skies today through
Monday. At the surface, we`ll see winds today switch around from the
west to the south, with breezy conditions showing up again Monday as
the pressure gradient tightens between high pressure centered over
the central Appalachians and a front moving across the Dakotas.
We`ll be well short of advisory levels, but gusts up around 25 mph
out in western MN look likely.

For temperatures, highs overachieved the NBM by a few degrees on
Saturday with full sunshine. With full sunshine expected again today
and Monday, nudged highs both days toward the 90th percentile from
the NBM with a couple more spectacular fall days expected. With the
warmer daytime highs, we will not be as cold overnight, with the
threat for a frost/freeze Monday morning being pretty much nil.

Only concern this period is we will have near-critical fire weather
conditions from west central into south central MN Monday. Highs
into the mid/upper 70s will send afternoon humdities down to around
25%, which when combined with winds mentioned early will result in
near-critical fire weather conditions.

.LONG TERM...(Monday night through Saturday)
Issued at 324 AM CDT Sun Oct 17 2021

Mild conditions are expected Monday night with lows in the upper 40s
to lower 50s. Tuesday will be warm again, though not quite as warm
as Monday, with highs forecast in the upper 60s to lower 70s. Skies
will have a couple more clouds due to southerly flow advecting in
slightly more moist air ahead of an approaching shortwave. Speaking
of said shortwave (our mid-week system), its track and evolution
still remain largely unchanged in the latest guidance. As it moves
east across the Central Plains Tuesday night into Wednesday, a
surface low will develop over central NE, tracking east thru
southern MN/northern IA and into WI. It should be noted that the
latest ECMWF and GEM do favor a slightly more southern low track.
Regardless of track, nearly all of the MPX CWA should see rain/rain
showers throughout Wednesday associated with a deformation zone and
trowal north/northwest of the low. The system and precip will move
east, with the rain eventually clearing our area Thursday morning.
Deterministic models and ensembles generally agree on 0.25-0.5" of
QPF across the CWA, though the GFS does hint the possibility of an
enhanced mesoscale band. However, will have to wait for CAMs to come
in range before considering potential/placement of mesoscale banding.

Cooler air immediately follows the system. This, combined with the
increased cloud cover, will mean Wednesday`s highs cool to the mid
60s in our southeast to mid 50s in our northwest. Lows Wednesday
night are forecast in the mid 30s in western MN to near 40 in west-
central WI. Temperatures continue their downward trend to below
normal for the end of the work-week as northwest upper-level flow
sets up. Highs Thursday and Friday are forecast to only reach the
upper 40s to lower 50s. Lows Friday and Saturday morning will be
quite chilly. In fact, a majority of the CWA will likely see frost
these mornings as temperatures dip into the lower to mid 30s.
Counties along our north should drop below freezing, especially
Friday morning.

Long-range models suggest temperatures moderate heading through next
weekend as the upper-level flow becomes more zonal. Rather large
differences exist between specific ridge and trough placements
beyond the period, which is mostly expected. However, one thing
models do tend to agree on is the arrival of a strong jetstreak
within the northern stream on the west coast early next week. Such a
feature may cause our weather to turn more interesting during the
final days of October.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 646 AM CDT Sun Oct 17 2021

Continued clear skies, with winds slowly backing to the SSE by this
evening with speeds under 10 kts.

KMSP...We`ll spend most of the day with a cross wind that favors use
of the 30s, with a switch to a 12s favorable direction happening
around sunset.

Mon...VFR. Wind S 10G20 kts.
Tue...VFR. Wind S 5-10 kts.
Wed...MVFR. -SHRA likely. Wind ENE 5-10 kts.





NWS MPX Office Area Forecast Discussion