Area Forecast Discussion
Issued by NWS Twin Cities, MN

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525
FXUS63 KMPX 211130
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
530 AM CST Tue Nov 21 2017

.updated for 12z aviation discussion below...

.SHORT TERM...(Today and tonight)
Issued at 330 AM CST Tue Nov 21 2017

The short term concerns are wind, extent of cloud cover and
temperature trends today.

Gusty northwest winds in the wake of the front have been gusting
to 30 to 35 kts over much of central MN cwa during the early
morning. Stronger caa and pressure gradient are increasing a bit
and we should see winds increase from west to south this morning.
Appears we may see a few sustained 30 mph with gusts mainly 40
mph...perhaps a stray 45 mph into the southwest mainly through
the morning. Wind advisory looks marginal at best but will let it
ride at least for the morning.

Clouds are dropping south and should encompass at least the
northern 2/3rds of the area through much of the morning. Models
continue to trend clearing quickly from the west through the
morning however, as the upper trough swings quickly east. Did
mention some flurries into the northern third of the are as well,
mainly this morning. Temperatures will continue to slide through
at least midmorning before becoming steady, maybe rebounding a
degree or two if clearing sun appear for most of the afternoon.

Clear overnight with light winds as high pressure moves through.
THis should provide temperatures in the teens.

.LONG TERM...(Wednesday through Monday)
Issued at 330 AM CST Tue Nov 21 2017

The extended still looks to be dominated by a relatively fast and
progressive flow with no significant winter systems and pretty
strong temperature swings centered around frontal passages. Model
agreement is still good through about 4 days, which gets us through
Friday, but diverge thereafter.  Only changes made to the
blended forecast were to increase winds Friday and Friday night in
the wake of what will be our next cold front.

Strong flow at the crest of of a ridge over the southern Canadian
Rockies looks to result in the development of a surface low over
southern Alberta tonight. That surface low will ride a baroclinic
zone southeast toward southern MN by Wednesday evening. Strong
isentropic ascent and warm frontal forcing looks to result in a
shield of light snow developing over northeast ND Wednesday morning
that will track east toward central and northern MN Wednesday
afternoon and northern WI Wednesday evening. Antecedent environment
ahead of this forcing still looks really dry and much of the time we
have forcing for precip will be spent moistening the atmosphere,
which should really limit precip potential. NAM shows a bit better
low level moistening down toward the Twin Cities, which is why it
drags precip farther south than the GFS and ECMWF. Sided toward the
GEFS/SREF probs for precip though, which keeps most of it north of
the MPX area. Even so, we are talking about a couple of hundredths
of an inch of QPF, so snow amounts, if we see any look minimal.

For Thanksgiving, it look ideal for this region, with light winds,
mostly sunny skies and highs around 40 as weak surface ridging moves
across the area.

The next system heading our direction will be moving out on to the
Canadian Prairies Thursday night, with a deepening sfc low going
across southern Canada during the day Friday. This will draw another
warm sector up toward us for Friday, though the peak of the warm
nose looks to move across the MPX area Friday morning. Still, model
spread is pretty strong that even in the Twin Cities, we`ll crack 50
for the first time this month. The SuperBlend has finally caught on
to these warmer temps, so no changes were needed to it. Like today
though, dense cloud cover could sink the Twin Cities attempt at 50.
During the afternoon, a strong westerly jet streak looks to come
across SD. GFS/ECMWF continue to generate an area of precip with the
lift on the nose of this jet streak, so increased pops into the high
chance/low likely category. Precip type will not be an issue with
this precip though as it will plenty warm enough to keep it all rain.

Friday night into Saturday, we get into another post frontal
environment similar to what we have tonight into this morning. Once
again, we should see borderline wind advisory winds behind the front
going into Saturday morning, with strong CAA resulting in falling
temperatures and highs Saturday that are about 20 degrees colder
than Friday.

Like we have been experiencing the last week, we will have two cold
days Saturday and Sunday, but we will head the other direction
by Monday with highs surging back into the 40s ahead of our next
system, which looks to be due in Monday night/Tuesday. This system
looks similar to what passed to our north last night and will pass
to our north Friday. The only difference is that this time around
the ECMWF/GFS have the low going across northern MN as opposed to
southern Canada. The impact of that is it would bring the heavier
precip closer to us. However, this pattern we have been in has only
shown much forecast reliability out about 4 days. So don`t bank on
this system being reliably forecast until we get to Friday or
Saturday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 515 AM CST Tue Nov 21 2017

MVFR cigs isold -shsn dropping south over the area this morning.
Will mention -sn at KAXN/KSTC/KMSP/KRNH for a few hours this
morning. We should see improvement from west to east through the
morning, becoming vfr and eventually clearing through 00z.
Northwest winds gusting to 36kts look to be a good bet through at
least the morning then decreasing/diminishing through 00z.

KMSP...
May see a period of mvfr cigs this morning as colder air arrives.
Expect trend to be vfr cigs 3500-4500 feet and becoming SKC after
22z. Maybe some high clouds moving back in into Wed morning. NW
winds gusting to 35kts yet perhaps for the next few hours as the
upper trough exits to the east. May see a passing flurry but
shouldn`t be anything significant.

/OUTLOOK FOR KMSP/
Wed night...VFR. Winds SW 5-10 kts becoming NW late.
Thu...VFR. Winds NW 5 kts.
Fri...Mainly VFR. Chance MVFR/-SHRA late. Winds SW 10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...Wind Advisory until 2 PM CST this afternoon for MNZ064-065-067-
     073>075-082>084-091>093.

     Wind Advisory until noon CST today for MNZ041-047-048-054>057.

&&

$$

SHORT TERM...DWE
LONG TERM...MPG
AVIATION...DWE



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