Area Forecast Discussion
Issued by NWS Twin Cities, MN

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
194
FXUS63 KMPX 201149
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
549 AM CST Mon Nov 20 2017

.UPDATE...For 12z Aviation discussion below

&&

.SHORT TERM...(Today and tonight)
Issued at 333 AM CST Mon Nov 20 2017

A fairly benign short term period is expected, with the only
headline being the potential for the warmest temperatures we`ve
seen thus far in November (including possibly hitting 50 degrees
for the first time at KMSP and KEAU). We look to mix to around or
just above 925mb, but will also have a fairly dense layer of
cirrus moving overhead. Think upper 40s to mid 50s will be
common, with the warmest readings along the Buffalo Ridge.

A cold front moves through (dry) tonight, and brings an abrupt
switch to brisk northwest winds by daybreak Tuesday. Lows will
fall into the upper teens to upper 20s, with little warming
expected on Tuesday.

.LONG TERM...(Tuesday through Sunday)
Issued at 333 AM CST Mon Nov 20 2017

The extended still looks to be dominated by a relatively fast and
progressive flow with minimal precipitation chances and pretty
strong temperature swings centered around frontal passages. Model
agreement is still good through about 4 days, which gets us through
Thanksgiving, but diverge thereafter.  Only changes made to the
blended forecast were to increase winds Tuesday and warm lows
Friday, highs Friday, and lows Saturday a few degrees.

We will be starting the long term period with temperatures on a
steep downward slide Tuesday in the wake of the cold front moving
through tonight. The windiest portion of the day still looks to be
in the morning. Top of the channel winds off the NAM and GFS get up
into the low 40 kts., so still anticipate some northwest wind gusts
up around 40 mph for our typical windy locations from western
through south central MN. Given how cold our 925 mb temps are by
Tuesday afternoon, not looking for much of a rise in temperatures
during the day, with highs largely remaining in the 20s and in a lot
of cases will be 20-25 degrees colder than what we see today for
highs.

For Wednesday, the zonal flow aloft will result in cyclogenesis over
southern Alberta Tuesday night that will track toward southwest MN
by Wednesday evening. There looks to be a WAA band of precip
that develops to the north of this surface low track across the
Dakotas on Wednesday. As this wave and snow move east, it will be
encountering increasingly drier air over MN. To go with this, all
but the ECMWF show the fgen and waa with this wave getting sheared
out as it moves into MN, which is why we decreased pops further.
Can`t rule out some flurries occurring across western MN as this
wave approaches from the Dakotas, but much more than that looks
unlikely.

No significant weather is expected for Thanksgiving. We will see a
weak cold front pass through during the early morning hours, but by
the afternoon we will already be seeing WAA. Looking at model
spread, or current forecast is on the lower end of the guidance
envelope, so wouldn`t be surprised if Thanksgiving ends up being a
couple of degrees warmer than what we currently have.

We`re starting to get better agreement with how Friday will unfold
in the models. The general consensus is that much like today, a
strong surface low will track across southern Canada, placing us in
another mild warm sector, with a good chance at cracking 50 again
for areas along and south of I-94. The majority of the precip looks
to be up closer to the surface low, but with surface dewpoints
creeping up to near 40, there will be a better chance for generating
showers locally as the shortwave and associated vorticity advection
move through. Most of the models show a band of showers developing
during the afternoon from eastern MN into western WI, though
temperatures look plenty warm enough to make this almost all rain,
so it will have minimal impacts to travel.  This band of showers
will also mark the return of cooler and drier air as a Canadian high
moves back in for Saturday and Sunday. This looks to knock highs
back into the 30s to finish out the holiday weekend. It looks dry as
well, so all-in-all, the weather looks great from the perspective of
driving across the region the entire holiday weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 550 AM CST Mon Nov 20 2017

VFR is expected through the period, with BKN-OVC cirrus clouds
today, then bkn-ovc low-end VFR clouds around 5KFT arriving late
tonight as a cold front approaches. Southerly winds will become
southwest later today as the front approaches, and then shift to
the northwest behind the front tonight. Strong northwest winds
will develop in its wake with wind gusts of 35-40 knots possible
around daybreak Tuesday.

KMSP...
Other than a slight chance for 2k-4k ft cigs on Tuesday morning in
the wake of the front, VFR conditions are expected with the only
other concern being gusty northwest winds.

/OUTLOOK FOR KMSP/
TUE...Slight chance of MVFR cigs in morning. Winds NW 15-20G30-35
kts.
WED...VFR. Winds SW 5-10 kts.
THU...VFR. Winds NW to W 5kts.


&&

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

$$

SHORT TERM...LS
LONG TERM...MPG
AVIATION...LS



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.