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.

439
FXUS63 KMPX 302341
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
541 PM CST Mon Dec 30 2024

.KEY MESSAGES...

- Fog improving by late evening.

- Chances for light snow or flurries through Tuesday, otherwise
  dry until potential snow system this weekend.

- Temperatures gradually decrease through the weekend, dropping
  below zero by Saturday morning in western MN.

&&

.DISCUSSION...
Issued at 304 PM CST Mon Dec 30 2024

Fog! Visibilities have generally improved across Minnesota and
Wisconsin this afternoon, with the worst conditions along the
Minnesota river in SW MN extending into portions of SE MN and
western WI. HREF probability of vis at a quarter mile or less
gradually falls off this evening from north to south, dropping below
30% by midnight and below 5% by daybreak. Once this fog is gone, we
should be largely fog-free moving forward as drier, cooler air
settles in from the northwest the rest of the week.

With this cooler Canadian air comes a few chances of light snow
and flurries through Tuesday. The first comes this afternoon
and evening as a wave travels across eastern SoDak, southwest
MN, and IA. Surface obs have shown mainly rain early this
afternoon across SW MN, but that is expected to transition to
light snow by this evening. As that system move southeast, a nub
of moisture looks to extend up into central MN and western WI,
potentially squeezing out some light snow or flurries overnight.
Heading into tomorrow, our low level stratus deck will be right
within the DGZ, which could result in another period of light
snow, especially along and north of I-94. With all of these
chances for snow, little to no accumulation is expected.

The rest of the week should remain quiet, with surface high pressure
in place across the central US. We`ll lose roughly 5 degrees to our
highs and lows each day thanks to the persist CAA from the
northwest. For any fans of the sun out there, the high pressure
should help brighten things up, especially on Thursday and Friday.

There continues to be a signal for a strong wave developing over the
western US and tracking through the central US by late this weekend.
With each passing model run, the trend favors areas to our south
seeing the majority of QPF with this system. NBM PoPs remain around
20 to 40 percent to account for any future shift or lighter snow to
the north. Both the Euro and GFS ensemble have a variety of outputs,
with about half their members bringing 2"+ and a quarter bringing no
snow at all (to the Twin Cities). One thing that we can
guarantee with this weekend system, if any precip does fall for
us, it will be all snow... it`ll be a proper cold, winter
weekend!

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 534 PM CST Mon Dec 30 2024

The fog and low stratus persists this evening, but this looks to
be the last of the persistent VLIFR conditions as increased NW
winds will develop overnight through tomorrow which will help
scour out some of the low level moisture. Visibilities will be
the first to improve, getting MVFR levels overnight and VFR
tomorrow. However, the low stratus will remain in place through
the day tomorrow, but ceilings will increase from IFR to MVFR
mid-to-late day. Any rain/snow showers over far southern MN will
remain there, thus keeping chances too low for inclusion at any
of the TAF sites.

KMSP...While ceilings remain around 200ft through at least some
of this evening, visibilities are already improving, owing to
the increase winds developing across the region. Visibility has
improved to IFR at initialization and will likely reach VFR
prior to daybreak Tuesday morning. IFR-or-worse ceilings will
persist through late morning, with slow improvement through the
MVFR range expected mid-to-late day Tuesday.

/OUTLOOK FOR KMSP/
WED...MVFR/VFR cigs. Wind NW 10-20G25 kts.
THU...VFR. chc MVFR. Wind NW 10-20G25 kts.
FRI...VFR. Wind NW 10-20G25 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Dense Fog Advisory until midnight CST tonight for Anoka-Benton-
     Blue Earth-Brown-Carver-Chippewa-Chisago-Dakota-Douglas-
     Faribault-Freeborn-Goodhue-Hennepin-Isanti-Kanabec-
     Kandiyohi-Lac Qui Parle-Le Sueur-Martin-McLeod-Meeker-
     Mille Lacs-Morrison-Nicollet-Pope-Ramsey-Redwood-Renville-
     Rice-Scott-Sherburne-Sibley-Stearns-Steele-Stevens-Swift-
     Todd-Waseca-Washington-Watonwan-Wright-Yellow Medicine.
WI...Dense Fog Advisory until midnight CST tonight for Barron-
     Chippewa-Dunn-Eau Claire-Pepin-Pierce-Polk-Rusk-St. Croix.

&&

$$

DISCUSSION...BED
AVIATION...JPC

NWS MPX Office Area Forecast Discussion