Area Forecast Discussion
Issued by NWS Twin Cities, MN

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868
FXUS63 KMPX 271934
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
234 PM CDT WED JUL 27 2016

.UPDATED FOR 18Z AVIATION DISCUSSION...
Issued at 216 PM CDT Wed Jul 27 2016

&&

.SHORT TERM...(Today and tonight)
Issued at 430 AM CDT Wed Jul 27 2016

Radar loops this morning nicely show the two waves of interest for
the weather the rest of today. This first is a nice spin up around
Fargo, with the other being an MCV over northeast Neb that is left
over from an MCS that tracked from east of the Black Hills down into
north-central KS overnight. Models initialized the northern wave
well, but this MCV in Neb went largely unnoticed by the 27.00 model
runs. For the 27.00 models, it is this wave up by Fargo that will
slowly slide down I-94 through the day that much of the guidance is
keying in on for bringing us precip chances today, though the
Nebraska MCV could end up being problematic for the pop forecast for
today, especially if it can help spur development later in the day
to our south that is currently not forecast to happen.

This morning, we are see showers and thunderstorms moving into
western and across central MN within zone of slightly stronger
winds and temp/moisture advection with the 925-850mb winds. However,
these already weak 925-850 winds will weaken to virtually nothing
this morning, with the coverage of showers expected to diminish
through the morning before diurnal heating destabilizes the
atmosphere, allowing shower and thunderstorm coverage to build again
by late this morning and into the afternoon. Biggest change needed
for the pops is both deterministic and CAMs are fairly progressive
with the wave up by Fargo through tonight, which will result in a
much faster west to east ending of precip than what the previous
forecast had. Though we sped up the precip departure considerably
tonight, we are still slower than what the majority of CAMs depict.

Still not anticipating much of a severe threat. The one thing that
is of some concern is that this afternoon, a weak surface low will
be tracking across the area, but there will be virtually no flow at
h850 and h5 winds will be under 20kts, resulting in very little
shear, which means little organization to what will be pulse/airmass
thunderstorms. Extensive cloud cover will also limit the degree to
which we can destabilize and instability looks to be weak enough
where updrafts will not be strong enough to generate much of a hail
or even wind threat with this activity.

.LONG TERM...(Thursday through Tuesday)
Issued at 430 AM CDT Wed Jul 27 2016

A cooler and drier air mass will settle in across MN/WI Thursday
and Friday behind the rain and cold front that will pass through
the area today and tonight. A surface high will move across the
Upper Mississippi River Valley late this week and the flow will
remain weak through the depth of the atmosphere. There will be a
weak northwest flow aloft with light and somewhat variable winds
in the lower atmosphere. Friday morning will likely be the
coolest morning we`ve had since July 1st when we saw lows in the
40s and 50s locally. We have a chance for showers/storms in
western MN on Saturday when the 925-850mb flow increases across
the Dakotas and the low level jet approaches the western MN border
- not likely at this point - but possible.

The pattern turns a little more interesting by Monday-Tuesday when
the flow increases out of the west-southwest with building
heights as a trough digs in across British Columbia and crosses
the northern Rockies by Monday night. This will certainly bring
about an increase in temperatures and humidity locally by Tuesday
- perhaps a couple rounds of showers/storms. The rain chances are
still highly uncertain given it`s 1) a day six forecast and 2) the
convective trigger is weak as the surface boundary doesn`t look
very strong and the upper support remains well north of the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 216 PM CDT Wed Jul 27 2016

MVFR/IFR conditions with the showers and thunderstorms this
afternoon. The storms will shift east this afternoon and should
exit the region by this evening. Northerly winds will develop and
bring drier air across the region, but forecast soundings show low
clouds developing overnight, especially in eastern MN and western
WI. The clouds should dissipate by late morning or early
afternoon.

KMSP...
A few showers and thunderstorms are possible at KMSP through
mid afternoon ahead of passing cold front. Winds will then become
northwesterly, with low stratus expected to develop overnight and
scattering out by late morning.

/OUTLOOK FOR KMSP/
Thu...VFR by afternoon. Winds NE 5 kts.
Fri...VFR. Winds E 5 kts.
Sat...VFR. Winds SE 5 kts.

&&

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

$$

SHORT TERM...MPG
LONG TERM...CLF
AVIATION...JRB



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