Area Forecast Discussion
Issued by NWS Twin Cities, MN

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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

FXUS63 KMPX 171821

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1221 PM CST Fri Nov 17 2017


Updated for the 18Z aviation discussion below.


.SHORT TERM...(Today and tonight)
Issued at 355 AM CST Fri Nov 17 2017

Light precipitation is occurring over the west central Wisconsin
portion of the forecast area this morning, in response to weak
moisture advection north/east of a warm front edging into
southwestern Minnesota. So far either light rain or light snow has
been observed, but cannot entirely rule out a brief window of
light freezing drizzle this morning over Polk/Barron/Rusk/Chippewa
counties where surface temps are currently at 32 degrees. Any
freezing precipitation would be light and brief, so ice
accumulations are not expected.

This afternoon a healthy band of 700-600mb frontogenesis develops
from central MN across southeast MN and west central WI. Expect
fairly widespread rain to occur, briefly mixing with snow tonight
prior to ending by daybreak Saturday.

Despite the blanket of stratus clouds, temperatures will be mild,
with highs in the upper 30s to mid 40s.

.LONG TERM...(Saturday through Thursday)
Issued at 355 AM CST Fri Nov 17 2017

For a time of year that can often have significant storm systems and
high impact weather, weather will be considerably lacking, with
no precip currently forecast through the entirety of the long term
period. Instead, the long term looks to be marked by fairly
progressive flow that will feature dry fropas every 2-3 days. Ahead
of these fronts, we`ll see highs poke up into at least the 40s, with
breezy northwest winds and highs in the 20s/30s in their wake.

We`ll start the long term in one of those cold NW wind patterns as a
surface low deepens on its trek across the Great Lakes, with high
pressure coming at us from the Plains. Though relatively cool, it
does look like the weekend will offer us periods of sun/clear skies
as the stratus will be quickly pushing off to our east Saturday
morning, with nothing but some passing mid/high clouds expected the
rest of the weekend. Monday will see a good surge of warm air.
Though this time, it will not come with dewpoints in the 40s, but
rather dewpoints staying back in the 20s. So this time around the
warm air will not come with dense stratus, but will rather have
mainly clear skies to work with. Based on 925mb temps between 6c and
10c and mainly sunny skies, could certainly see highs ending up a
few degrees warmer than what we have, with 50 not out of the
question even for the Twin Cities.

The warmth of Monday will be quickly pushed out though Monday night
as another strong cold front moves through. Monday night into
Tuesday looks similar to what we are expecting tonight, though winds
could be a bit stronger as the CAA really kicks in late Monday
night. This CAA will result in cool days Tuesday and Wednesday.
Depending on where a surface ridge axis sets up Wednesday morning,
we could certainly see lows dip into the single digits in spots.

For Thanksgiving we get back into a WAA regime and like Monday, our
current forecast is on the conservative side of the envelop for max
temperatures, with the next cold front coming through either
Thursday night or later in the day Friday. At either rate, the
second half of the holiday weekend looks to be considerably colder
than the first half.  The good news though is through all of this,
we only look to be dealing with Pacific moisture that the Rockies
will have adequately rung out of the atmosphere before getting here.
In fact, the full 10 days of the Canadian/GFS/ECMWF show no
additional precip locally after what we get past today/tonight.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1208 PM CST Fri Nov 17 2017

Low stratus and drizzle across much of eastern MN and western WI
as expected early this afternoon. The incoming cold front is
pushing into extreme western Minnesota as southeast winds have
turned around to northwesterly in that area. An inverted surface
trough axis extending north northeastward from far eastern
Nebraska has been a good dividing line between the low stratus and
drizzle to the east of that line, and mainly passing high clouds
to the west with as the low clouds get scoured out.

So, the guidance may be overly pessimistic today in how far east
the vfr cigs make it. It`s reasonable though to expect the stratus
to halt its progression this evening until the actual cold front
moves through overnight to scour out the moisture. Currently
trending to that forecast for eastern MN and western WI, which
means continued MVFR or even IFR at times through the night, with
improvement tomorrow.

KMSP...Already seeing VFR cigs about 50-75 miles west of MSP, so
it is a bit of a concern that the forecast may be too pessimistic.
Latest satellite trends do show some new formation of stratocu to
the west, and the models would say that trend should continue. For
now, felt this was the most likely scenario but will monitor
closely if conditions change.

Sun...VFR. Wind SW-W 5-10 kts.
Mon...VFR. Wind S 5-10 kts.
Tue...VFR. Wind NW 10-20 kts.




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