Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 190857
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
257 AM CST Sun Nov 19 2017

.SHORT TERM...(Today and tonight)
Issued at 256 AM CST Sun Nov 19 2017

Surface ridge axis centered over MN this morning will push into the
Great Lakes today, setting the stage for the beginnings of a warming
trend. Aloft we will have have fairly strong NW flow though, which
based on up stream satellite will supply us a veil of high clouds
most of the day. We`ll have a pretty good gradient in temperatures
today between the cold air to the east and the warm air coming back
from the southwest. Trended the forecast closer to the ECMWF. This
kept the extremes more or less the same, with highs near 50 out in
west central MN and near 30 in Ladysmith, but did expand the 40
degree highs a bit farther east, getting those into St. Cloud, the
Twin Cities and Albert Lea.

Tonight, we will keep a southwest wind and continued WAA
in place, which will keep lows Monday morning a good 10 to 15
degrees warmer than what we are seeing this morning.

.LONG TERM...(Monday through Saturday)
Issued at 256 AM CST Sun Nov 19 2017

The long term will be marked by fairly fast and progressive flow,
with a fairly strong thermal gradient meandering across the northern
CONUS.  Patterns like this are notoriously difficult to model much
more than 3/4 days out and we are seeing that in the ensembles. 500
height forecasts from the GEFS and EPS are tightly clustered through
Tuesday (day 3), begin to diverge Wednesday (day 4), and have pretty
wide spread by Friday (day 6).  Net result, is we did not stray too
far from the blended forecast, with the only change being to again
warm highs Friday a few degrees.

All signs continue to point to Monday being one of the warmest days
we have seen this entire month. There will be a strong surface low
going across southern Canada, with its associated cold front moving
into west central MN in the afternoon. This will put the warm sector
for this system across our area during peak heating. The only thing
that may hold temperatures back will be the increasing mid/upper
level clouds during the afternoon as the surface lows parent
shortwave approaches from the northwest. Chances are increasing
that MSP will finally see it`s first 50 of November 20 days into the
month.

Said cold front still looks rather strong, with h85 temps going from
around +10C Monday afternoon, to around -12C Tuesday afternoon. We
also continue to see a strong isallobaric high coming in behind the
front. Looking at mixing on forecast soundings, along with the
strength of the isallobaric high coming in behind the front, we will
likely see winds gusting to around 40 mph for the first 2 or 3 hours
after FROPA, with wind gusts remaining up in that 30-35 mph range into
Tuesday afternoon. For Tuesday afternoon, did nudge highs below the
blended mean, with 925-850 temps on the ECMWF only supporting highs
in the 20s area wide, which will be around 25 degrees colder than
the highs for Monday.

With the strong flow remaining in place, the 19.00 runs continue a
trend started with the 18.12 runs with a bit of WAA precip coming
across the Dakotas Tuesday night and possibly moving into MN
Wednesday. GFS soundings show there being a lot of dry air
to overcome, with that dry air being overcome at about the time the
forcing is moving out, so this looks like a mainly virga event for
us. At worst, we could see a half inch of snow across mainly central
MN, but that looks fairly unlikely at this point.

This bit of forcing for snow moving through Wednesday will be coming
in on the cool side of a very strong baroclinic zone that will be
coming across the Dakotas. This baroclinic zone will be in our
neighborhood Thursday and Friday, which leads to lower confidence for
the temperature forecast Thursday and Friday. This will be a tight
gradient and it will not take much of a shift in terms of
placement and timing of the gradient to send our highs closer to 30
or closer to 60 both days. This baroclinic zone along with jetting
aloft will also be a potential breeding ground for cyclogenesis at
the end of the week, but there is low confidence on if/where/when we
would see it. The ECMWF is a case in point on the volatility in the
models for the end of the week as 24 hours ago it had nothing, 12
hours ago developed a rather strong system over MN/WI, with the most
recent run still developing a system, but a much weaker one with
what was seen with the 18.12 run. As a result, did not change much
from our blend, which has fairly low PoPs Friday into Saturday
morning. Even so, looking at thermal profiles for when a model
generates precip, we look to be warm enough for a mainly rain to a
brief period of snow scenario.

For the second half of the holiday weekend, high pressure coming in
from Canada will give us a much colder finish to the weekend than
what we see Thursday and Friday, but even here there is good model
spread. The ECMWF continues to be deeper with a trough to our east
and considerably colder than the GFS. Though both models keep us dry
to end the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1114 PM CST Sat Nov 18 2017

MVFR clouds are hanging tough out in WI, though NAM/RAP forecast
soundings show that even at EAU, they should be gone after 9z. No
concerns the rest of the period with high confidence in the TAFs,
with nothing more than some passing mid/high clouds with winds
becoming increasingly southwest.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/
MON...VFR. Winds SW 10 kts.
TUE...MVFR cigs in morning. Winds NW 15-20G30-35 kts.
WED...VFR. Winds SW 5-10 kts.


&&

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

$$

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



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