Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 291752
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1252 PM CDT THU SEP 29 2016

.SHORT TERM...(Today and tonight)
Issued at 323 AM CDT Thu Sep 29 2016

Little change in today`s or tonight`s forecast as Minnesota and
western Wisconsin will remain between an area of high pressure that
was north of the Canadian border, and a storm system in the Ohio
Valley. Winds will be lighter today as the storm system and pressure
gradient is not as strong. The strongest winds will occur closer to
the area of low pressure in southeast Minnesota and west central
Wisconsin. Some cloud cover today should quickly dissipate this
afternoon as dry air mixes down in the boundary layer.

.LONG TERM...(Friday through Wednesday)
Issued at 323 AM CDT Thu Sep 29 2016

The massive upper level low centered near KIND early this morning
remains on track to sink south into KY by Friday morning and then
begin lifting back NNW to the lower Great Lakes by Sunday and then
slowly open up and head into New England for early next week. The
GFS has come around to the EC idea of this wave over the northeast
for early next week which has implications on a western U.S.
system, with more on that later.

With the upper low lifting northward this weekend, there will be
another surge of low/mid level moisture shoved westward into the
FA from Friday night through Saturday night. Various solutions are
basically dry for the Twin Cities on west with some small pops for
areas of western WI. This seems reasonable when looking at
300/305K theta charts which show pretty strong downglide into
eastern MN. A little disconcerting however is the Q-Vector
convergence moving across western WI and eastern MN in the H5-H3
layer. Just the opposite signal is seen in the H8-H5 layer. For
now, it looks like a mostly cloudy day for much of the region on
Saturday. One cannot rule out a few sprinkles in eastern MN with
a few light showers across western WI. Partly cloudy conditions
are then expected for Sunday.

For next week, a large upper level low pressure system will push
into the western U.S. This feature has been well advertised by
the EC/GFS. In the past 24 hours, the GFS has come around to the
EC idea of a much slower evolution of this system into the
central and northern plains. This goes back to the trough over the
northeast early next week which the GFS didn`t have 24 hours ago.
Anyway, the 00z CR-Extended grids still had pops racing in here
Monday afternoon with areal coverage on Tuesday. This is way too
fast and if one were to stay with the EC it wouldn`t likely rain
in the Twin Cities until Wednesday afternoon. Therefore, all
offices agreed to slow the progression of the pops down, with
Monday night and Tuesday morning dry for our FA with small pops
allowed into western MN Tuesday afternoon. Chance pops then
progress across the FA Tuesday night and Wednesday with lingering
chances on the backside of the system for Thursday.

High temperatures remain in a very tight range from Friday
through next Tuesday with readings a few degrees either side of
70. Highs will then drop into the 50s and 60s by Thursday. Lows
are in a range from 45 to 55 through the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1238 PM CDT Thu Sep 29 2016

The upper low that was over the southern Great Lakes yesterday has
moved south into southern IN/northern KY, with a surface high in
Ontario. Stronger than expected northeast flow in between these
areas led to cool and moisture advection off Lake Superior this
morning and low ceilings moved in to parts of West Central
Wisconsin and eastern Minnesota. Farther south, LIFR ceilings and
fog have since dissipated. The southern end of the the stratus
from the Lake Superior is expected to slowly erode from the south
this afternoon and evening. STC and AXN will deal with the clouds
the longest, but bases should remain at VFR levels. Tonight, fog
will be possible across the area and included some mention of fog
at each TAF site. The HRRR indicates moisture off Superior
affecting north central MN, so we think AXN would be most
susceptible to fog overnight. ENE winds today will become light
overnight, and increase to near 7 knots from the NE tomorrow.
Clouds from the Upper Low will approach from the southeast
tomorrow during the day.

KMSP...Starting off with a tempo BKN025 for an hour as ceilings
should lift and continue a scattering trend this afternoon. Expect
clear skies tonight, but could see some fog early tomorrow
morning. ENE winds gusting to 16 knots this afternoon are expected
to become light tonight, and around 5-7 knots tomorrow. Could see
stratus filling in from the east tomorrow late afternoon as that
upper low lifts north.

/OUTLOOK FOR KMSP/
Sat...VFR. Wind ENE at 5 kts.
Sun...VFR. MVFR possible. Wind NE at 5 kts.
Mon...VFR. Wind SE at 5-10 kts

&&

.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&

$$

SHORT TERM...JLT
LONG TERM...RAH
AVIATION...SPD/AMK


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