Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 132053

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
353 PM CDT THU OCT 13 2016

.SHORT TERM...(This evening through Friday)
Issued at 355 PM CDT Thu Oct 13 2016

Surface analysis this afternoon puts the center of sprawling high
pressure over western IA with a potent storm system moving onshore
the Pacific Northwest. Aloft, a longwave trough axis is nearly N-S
from Lake Superior through the lower Mississippi River Valley and
a small ridge axis is aligned over the spine of the Rockies,
putting MN/WI within dry NW flow aloft. The surface high will
shift eastward overnight, centering itself over the eastern Great
Lakes by daybreak Friday morning then over New England by Friday
evening. Low level southerly flow will return in earnest tonight
through tomorrow. allowing for warmer temperatures and slightly
higher dewpoints to move into the region through tomorrow
afternoon. In addition, a tightened pressure gradient will develop
over the region during the day tomorrow, making for breezy
conditions across the region. However, plenty of sunshine will
still be realized despite the exodus of high pressure due to a
broad longwave ridge moving atop the region tomorrow. The
southerly flow plus higher H5 heights will spell an increase of
10-15 degrees in max temperatures tomorrow compared to today.
There will be a minor increase in high clouds tomorrow but nothing
worthy of impeding effective warm air advection. Minimum
temperatures tonight will also be warmer, thus no need for any
further freeze-related headlines or supplementary products.

.LONG TERM...(Friday night through Thursday)
Issued at 355 PM CDT Thu Oct 13 2016

We expect an increase in cloud cover and the potential for very
light rain, mist or drizzle late Friday night into Saturday
morning. The forecast soundings off the NAM/GFS show a couple
distinct cloud layers during this time period. There is a moist
layer aloft between 15-20kft which is the result of cirrus clouds
approaching from the mid-upper jet, but also a saturated layer in
the lowest 2-3kft. The LLJ Friday night is forecast to be
40-50kts, which will advect plenty of moisture northward from the
Southern Plains. Surface dewpoints will start in the 30s Friday
morning...climb to near 50 by sunset Friday...and to near 60
degrees by 12z Saturday. Soundings show saturation between
1000-3000ft with increasing omega in the lower atmosphere. The
soundings are also very dry above this saturated layer, so if the
lift isn`t strong enough to grow drizzle/rain drops in the lowest
2-3kft, then precipitation won`t happen until late in the day
Saturday when deeper moisture arrives near the advancing front -
along with weak instability. The main front drops south of the
forecast area Saturday night, but the much cooler/drier air hangs
back across ND/SD and southern Canada. The boundary returns
Sunday night, lifting north as a warm front as a deep surface low
lifts north across the northern High Plains. This warm front will
likely trigger a band of showers and storms somewhere across MN/WI
Sunday night into Monday morning - we are uncertain as to exactly
where at this point, but the rain coverage looks more widespread
along and north of the I-94 corridor. After warmer days FRI- SUN
where 70s are likely (at least where there is partial sunshine),
temperatures will fall back to start the work week Monday and


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1239 PM CDT Thu Oct 13 2016

Solid VFR conditions expected throughout the region. Only concern
will be winds overnight through tomorrow. Surface winds will
become south in the 5-10kt range. However, strong low level
jetting just atop the nightly inversion will develop in
southwestern MN and slowly spread ENE. After daybreak, mixing will
result in strong southerly winds approaching the 15G25kt area but
prior to daybreak, winds in the 1-2 kft level will increase to
30-40 kt from 210 to 220 direction. For most sites, this looks
more like low level turbulence rather than shear so have omitted
from all sites except KRWF which looks good to have the strong
enough vector difference to include LLWS mention.

KMSP...Aside from strong winds just off the deck around the time
of the morning push Friday morning, no other significant weather
concerns are expected.

Sat...MVFR with -SHRA possible. Wind SW at 10-15 kts.
Sun...VFR. Wind ESE around 5 kts.
Mon...VFR. Wind SW 5 kts becoming SE.


.MPX Watches/Warnings/Advisories...


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