Forecast Discussion / NWS-Twin Cities

591
FXUS63 KMPX 061729
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1129 AM CST Fri Dec 6 2024

.KEY MESSAGES...

- Relief from the bitter cold arrives this weekend, with above
  normal highs in the 40s Saturday and Sunday.

- Another shot of cold December air will drop temperatures into the
  teens for highs by the middle of next week.

- Chance for isolated snow showers early next week. Overall,
  precipitation chances are limited over the next seven days.

&&

.DISCUSSION...
Issued at 241 AM CST Fri Dec 6 2024

Nighttime microphysics satellite imagery reveals a layer of stratus
over most of the region early this morning. The stratus has combined
with light surface flow out of the south to slow warming across
western/central Minnesota. The impact on temepratures can easily be
seen by looking at the 24-hour temperature change, as locations
beneath the stratus are running 10-20 degrees warmer than this time
yesterday.

Surface analysis captures ~1030s mb high pressure centered over
Missouri, with gradual movement to the southeast ahead today. Water
vapor imagery over the Pacific Northwest depicts moisture over
western Canada, which is gradually advecting south and east amid the
continued upper-level northwesterly flow regime. We can already see
low stratus moving southeast out of Manitoba on Geocolor imagery.
Pair the upstream observations with forecast soundings and the
result is a rather pessimistic sky cover forecast Minnesota and
western Wisconsin today. Afternoon highs aim to finish below
freezing, in the mid to upper 20s for most of the area.

A shortwave and associated surface low is progged to move southeast
across southern Canada towards Lake Superior this weekend. Warm air
advection will increase across south central Minnesota and western
Wisconsin in association with this passing wave and as a result the
weekend forecast will feature a significant warm up. Temperatures
will only fall a few degrees between this afternoon and Saturday
morning as the advection increases. The aforementioned expansive
stratus this afternoon will lower/combine with sub-freezing
temperatures to produce the development of patchy freezing fog
tonight. This may lead to a few slick spots on the roads. After
daybreak Saturday, the stratus/fog will begin to mix out of the
picture and temperatures will be on the increase. Saturday afternoon
highs are set to top out well above normal, in the 40-50 degree
range. Temperatures will run slightly cooler on Sunday, with highs
in the upper 30s/lower 40s. Locations across southern Minnesota may
achieve the upper 40s for the second day in a row!

The upper-level northwest flow regime will breakdown as a trough
moves across the northern CONUS Sunday into Monday. The approach of
the trough/potent vort max will introduce likely precipitation
across northern Minnesota Sunday into Monday. We`ve included slight
chance PoPs north of I-94 to account for the potential of a few
raindrops or snowflakes. The better chance for snowflakes to fly
will be on Monday, as the vort max/surface low pivot northeast
over Lake Superior and moisture wraps around the backside of the
system within a region of increasing cold air advection. Still,
QPF appears to be light and any accumulations would likely be very
minor. The more notable local impact will be the decline in
temperatures, which are set to fall into the 20s for highs on
Tuesday and into the teens for highs on Wednesday. Overnight lows
dip back into the single digits and sub-zero wind chills eye a
return by midweek as well. Medium to long range guidance is
optimistic about a rebound in temperatures by late next week, as
large scale southwesterly flow sets up. This may also eventually
mean a more active pattern towards the middle of the month, but
for now there is no clear sign of meaningful precipitation in the
extended period.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1110 AM CST Fri Dec 6 2024

A mostly MVFR stratus deck is currently north of a line from
RWF to MSP to EAU. These clouds will continue to push south-
southeast, eventually covering all terminals by early this
afternoon. For RWF and MKT, at least of couple of hours of MVFR
look possible this afternoon before CAMs show skies lifting to
VFR for the remainder of the period. Elsewhere, at least MVFR is
expected into early Saturday morning with AXN and STC`s cigs
falling to LIFR during this evening. Fog/mist is also a good
possibility at AXN and STC with visibilities dropping to 0.5 to
1.5 miles. Low-level WAA early Saturday morning should dry out
the low-level profile, lifting conditions to VFR for all
terminals by sunrise. West-northwesterly winds of under 10 knots
this afternoon will turn south-southwesterly this evening,
falling to under 5 knots. Winds will become southwesterly,
increasing to near 10 knots by late Saturday morning.

KMSP...MVFR stratus (with cigs near 2000 feet) arrives at the
start of the period and cigs should fall to 1200 feet near 03Z.
Periods of IFR cigs are possible after midnight to before
sunrise so have added a TEMPO for this. VFR should prevail after
12Z Saturday.

/OUTLOOK FOR KMSP/
SUN...VFR. Wind S 5-10 kts.
MON...MVFR likely. Chc -RASN. Wind W 10-15G25-30 kts.
TUE...MVFR likely. Chc -SN late. Wind WNW 10-15G25 kts.

&&

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

&&

$$

DISCUSSION...Strus
AVIATION...CTG

NWS MPX Office Area Forecast Discussion