Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 280348

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1048 PM CDT TUE SEP 27 2016

.UPDATE...For 06z Aviation Discussion below


.SHORT TERM...(This evening through Wednesday)
Issued at 321 PM CDT Tue Sep 27 2016

An area of stratiform rain will move across eastern MN and western
WI this afternoon and evening. Rainfall totals will generally be
less than a tenth. The rain is driven by a enhanced area of PV along
a shortwave trough rotating around a cut off upper level low. This
PV anomaly will rotate southeast, and the rain will gradually end
from north to south as it does so.

By Wednesday morning expect lingering clouds and northerly winds.
Forecast soundings show the clouds will be slow to dissipate in
central/eastern MN and western WI. Meanwhile western MN will have
clear skies. The breezy northwest winds will gradually become
northerly, and eventually northeasterly on Wednesday.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 321 PM CDT Tue Sep 27 2016

We are still anticipating nearly perfect fall weather through
Monday, with only one small tweak to the forecast for Saturday with
the next front of significance and chance for rain arriving Monday
of next week.

Main player for the weather through the weekend will be the upper
low currently over Lake Superior. This low will be cut off from the
main westerlies and drift down into eastern Kentucky/Tennessee by
Friday morning, at which point the GFS/ECMWF show this upper low
retracing its foot steps, ending up back over Michigan on Saturday.
Being northwest of the low, we will see pleasant and dry conditions
under the influence of high pressure Thursday and Friday, but as the
upper low moves into Michigan, it`s cyclonic flow and associated
cloud cover will start backing into our eastern areas. We have seen
the GFS trend west with the low, toward the ECMWF over the past
couple of runs, which has a couple of implications for the forecast.
One, increased cloud cover now shows up on Saturday as far west as
the Twin Cities, while a chance for showers has been brought into
western WI.

For next week, we are still seeing timing differences for when an
upper trough building over the Rockies this weekend begins moving
out into the Plains. The GFS continues to be the most progressive
with it, bringing this system in Monday night, with the ECMWF 12-18
hours behind. Given the strength of the upper ridge this weekend
over eastern Canada, the slower progression is likely the way to go.
As a result, we removed Pops from the forecast for Sunday night and
delayed how quickly they push east Monday into Monday night.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1049 PM CDT Tue Sep 27 2016

Low clouds and ceilings are the main concern this TAF period.
MVFR-level clouds continue to sink from northern MN/WI into the
TAF area late this evening. Some earlier guidance was a bit too
optimistic per trends, and expect MVFR ceilings to prevail into
Wednesday morning. Even lower ceilings (IFR) are possible at WI
Sites (KRNH-KEAU). Clouds slowly scatter out on Wednesday, but
the MVFR deck will likely linger through the morning. North winds
prevail through the period with gusts up to 20kts possible again
during the day Wednesday.

Expect MVFR ceilings to prevail through Wednesday morning.
Sub-1800ft cigs are also expected to flutter in and out of the
site overnight...hence the tempo group.

Thu...VFR. Wind NE at 10kt
Fri...VFR. Wind NE at 05kt
Sat...VFR. Wind NE at 05kt.


.MPX Watches/Warnings/Advisories...


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