Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 161149

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
549 AM CST Thu Nov 16 2017

.UPDATE...For 12Z Aviation discussion below


.SHORT TERM...(Today and tonight)
Issued at 343 AM CST Thu Nov 16 2017

Stratus clouds trapped under the ridge will linger this morning,
scattering out for the afternoon as southeasterly flow strengthens
ahead of a High Plains trough. Despite the clearing of the low
clouds, peeks of the sun will likely be few and far between, given
mid/high clouds will be encroaching the area from the west as low
level moisture/warm air advection ensues ahead of the
aforementioned trough. Expect another day with temperatures
running below normal for mid-November. Highs will range from 35
to 40 degrees.

Late tonight weak lift develops generally north of Interstate 94 as
the warm front lifts toward central MN. Have included a 20 POP for
Rain/Snow after 06z Friday, but it could end up being more of a
drizzle scenario.

.LONG TERM...(Friday through Wednesday)
Issued at 343 AM CST Thu Nov 16 2017

A rather repetitive weather pattern is expected during the extended
and into Thanksgiving weekend, with two mild days, followed by two
cold days, then two warm days and so forth. Lacking in all of this
will be chances for precipitation, with a prolonged dry stretch of
weather expected after Friday.

We start the long term in one of those warm periods. However, this
will be the cloudy and drizzle filled version of a warm day like we
saw Tuesday, as dewpoints increasing into the 40s with the cold
ground will ensure we see more low stratus. Also like Tuesday,
forecast soundings show us lacking moisture in the DGZ, with a
nearly 5k foot deep moist layer near the surface, so more fun with
drizzle. Any chance at non drizzle will have to wait until Friday
night as the main upper trough swings through the area. By then
though, the surface low we be beginning its deepening phase down
near Chicago, which means just as the deep moisture arrives, the
forcing is pulling out. The net result is that QPF amounts look
limited once again, with precipitation gradually changing over to
snow from west to east Friday night.

For the weekend, it`s a repeat of what we saw Wednesday and are
expecting today, though with one difference and that`s that we
should actually get to the see the sun.  The combination of CAA and
isallobaric forcing will result in breezy northwest winds Friday
night, that will keep going into the day Friday as we add in some
diabatic heating and mixing. Winds will die off Saturday night and
turn to the southwest on Sunday, with warmer air starting to return,
which will lead us to our next warm day on Monday.

Monday`s version of a warm day looks to have a different feel to
what we saw Tuesday and are expecting Friday. As opposed to seeing
dewpoints climb into the 40s, resulting in dense stratus, Monday will
feature dewpoints in the 20s, which means we will have the
opportunity to see the sun with the warm weather. As a result,
Monday also has the potential to be considerably warmer than Tuesday
and Friday, especially given the favorable southwest wind direction
for going warmer. As a result, followed the previous shift in
raising highs for Monday a few degrees above blended guidance, with
low 50s from west central into south central MN, though there is
certainly potential we`ll need to go higher.

This warmth will be in response to warm air surging north ahead of a
cold front that will clear our area Monday night, ushering in
another period of strong northwest winds and tumbling temperatures
for Tuesday, though we look to get on the backside of the high
Wednesday with WAA beginning on Wednesday resulting in mild
temperatures for Thursday into Friday. There is a mention of precip
on Thursday and this is really based on the GFS, which has a clipper
system working down I-94. The ECMWF/Canadian have something similar,
only they have the precip clear up in southern Canada, so this
chance may very well disappear in the coming days.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 549 AM CST Thu Nov 16 2017

The primary TAF concern will be the question of when we will
shake this stratus deck. At the start of the TAF period ceilings
are ranging from 700FT (west) to 1700ft (east). Other than minor
fluctuations of a hundred feet or so, do not expect much change
for the first few hours of the TAF period with the surface ridge
still in place. Once southeast surface winds begin to pick up late
this morning and early afternoon and we get some mixing, think
we`ll see some progress with the scattering of the low cloud deck,
and improvement to VFR during the mid afternoon. With the
improvement to VFR we will also see surface winds becoming gusty
from the southeast, along with the arrival of a broken-overcast
mid level deck.

Ceilings are expected to remain just below 1700ft until around
16z, and then we stay MVFR level until around 20Z (but above 1700
ft). By late afternoon we look to shake the low clouds, but
southeast winds (140 degrees) become gusty to around or just over

Fri...MVFR with chance -DZ. Wind S becoming NW 5-15 kts.
Sat...VFR with MVFR early. Wind NW 10-20 kts.
Sun...VFR. Wind W at 10 kts.




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