Area Forecast Discussion
Issued by NWS Twin Cities, MN

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919
FXUS63 KMPX 281813
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
113 PM CDT WED SEP 28 2016

.SHORT TERM...(Today and tonight)
Issued at 320 AM CDT Wed Sep 28 2016

A broad circulation around a deep low pressure system across the
Great Lakes, will continue to wrap moisture and possibly a few light
rain showers across west central Wisconsin and east central, south
central Minnesota this afternoon. Water Vapor imagery this morning
does support of another "lobe" of energy moving southwest across
Wisconsin this afternoon. Although moisture depth will be shallower
compared to yesterday, this is enough lift associated with this
"lobe" to generate a few light rain showers. Even some of the local
models support isolated/scattered showers this afternoon in the area
mentioned before. However, I would not expect anything more than a
hundredth of an inch at best.

The other concern today is the persistent cloud cover which was to
scatter out overnight, but with the system a bit further to the west
and an Upper Ridge expected to build across southeast Canada, the
clouds will likely linger into the evening. Eventually drier air
will filter southwest as the Upper Ridge continues to build north of
the Great Lakes. Temperatures this afternoon will remain on the cool
side due to the cloud cover, so low to mid 60s are in the forecast.
However, normal high temperatures in this area for late September
are in the mid 60s.

.LONG TERM...(Thursday through Tuesday)
Issued at 320 AM CDT Wed Sep 28 2016

The large upper level low pressure system, currently sinking south
across the western Great Lakes, should bottom out over KY in the
Thursday to Friday time frame and then begin to lift slowly back
north-northwest through the upcoming weekend. This movement back
to the north is being brought about by a massive upper level
trough moving into western North America beginning late in the
week. There is actually good agreement, both on timing and
location, with this scenario between the EC and GFS. This movement
back to the north will bring a chance of showers to our eastern FA
on Saturday. Right now we think the showers will remain to the
east of the local area. In the meantime, Thursday and Friday look
great with plenty of sunshine.

Thereafter, the continuity between the EC and GFS dissipates
rapidly. This is mainly due to the EC hanging on to the upper low
over New England early next week while the GFS has ridging. Due to
the wave over New England, the EC is much slower on moving the
western trough eastward, while the GFS races this feature
northeast through the central and northern plains. The GFS would
practically have the precipitation event over for us on Wednesday
while the EC doesn`t have the precipitation here yet! Pretty high
pops are in place for Tuesday through Wednesday, but confidence
for when it actually starts is not high at this point. If one went
the route of the EC, there would be a little light rain on Tuesday
as low level theta-e advection ensues with any significant rain
not showing up until later on Wednesday. This is slowly than the
previous EC run and again tied to the upper trough over New
England early next week which the previous run was not so adamant
about. Even though the GFS is faster, it has slowed considerably
over it`s 27/18z run.

Nothing real dramatic in the temperature department with highs and
lows real close to seasonal normals through the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1254 PM CDT Wed Sep 28 2016

Stratus shield blanketed across the Upper Midwest this afternoon
has gradually lifted with pockets of VFR mixed in with MVFR cigs.
The ceiling should continue to slowly lift with all sites going
VFR this afternoon. The big concern with this forecast is for
tonight and tomorrow. Continue to advertise clearing of skies but
there is bust potential given the upper ridge axis takes until
tomorrow to reach our area. If the clouds are able to scatter out,
we could see fog form overnight which has been advertised in a few
of the sites.

KMSP...concern that the SKC forecast at 02Z could be really early.
A few models indicate the clouds could stick around and that MSP
might see MVFR ceilings form early tomorrow morning.

/OUTLOOK FOR KMSP/
Thu...VFR. Wind NE at 5-10kt
Fri...VFR. Wind ENE at 05kt
Sat...VFR. Wind ENE at 05kt.

&&

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

$$

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



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