Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 170848

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
348 AM CDT Thu Aug 17 2017

.SHORT TERM...(Today and tonight)
Issued at 345 AM CDT Thu Aug 17 2017

Surface analysis and KMPX radar imagery early this morning show the
center of low pressure over south-central MN, roughly between KHCD-
KMKT. Its warm front extends SE into the southern tip of Lake
Michigan continuing into central Ohio while its cold front curls
into eastern Iowa then SW over northern Missouri. Aloft, a bellowing
trough with a cutoff low within it over southwestern MN is helping
the surface feature along. Both features at the surface and aloft
will shift into WI by midday, being replaced by weak surface high
pressure and a minute ridge axis within the progressive flow aloft.
A fairly impressive rain shield persist over central into western MN
this morning, at times with rainfall rates exceeding 2"/hr. As the
tilted low shifts east, the rain shield will also steadily shift
east with rain persisting within an airmass that continues to
feature PWATs over 1.5". While the heaviest rain will still be
featured over western MN today, periods of moderate-heavy rain
certainly cannot be ruled out as the overall area of rain moves
east. Another concern is strong winds directly under and trailing
the surface low. Have already seen sustained winds around 30-35 kt
with gusts 40-50 kt (including a 51kt gust earlier at KRWF). This
punch of wind generally coincides with the track of the low so have
opted to issue a Wind Advisory for near and downstream of the
surface low. The duration of the winds is not expected to be more
than a couple/few hours but the speeds and coverage do warrant the
advisory. As the low spins off, conditions will gradually improve,
such that clearing skies may well be experienced this afternoon in
western MN, translating east into eastern MN and western WI this
evening. After skies clear out this evening into the early morning
hours, clouds will return from the west overnight through daybreak
tomorrow in advance of a weaker surface low and its associated north-
south oriented surface trough. A few showers are possible in far
western MN by daybreak tomorrow but nothing impressive.

As for temperatures, cooler again looks to be the way to go as the
today`s system will be slow to exit and likely block much insolation
for today. After early morning lows in the low-mid 60s this morning,
highs will range from the upper 60s in eastern MN and western WI to
the mid 60s in far western MN (owing to faster clearing out west).

.LONG TERM...(Friday through Wednesday)
Issued at 345 AM CDT Thu Aug 17 2017

Main concerns in the long term remain timing and strength of
short wave moving through Friday and timing of next frontal
passage Sunday into Monday night.

Deterministic models are in decent agreement in bringing a short
wave through the region Friday/Friday evening. Instability is
there and shear will depend on how strong the wave be as it moves
through. Marginal risk over the southwest looks good for day 2
outlook at this time.

Drying is expected as high pressure builds over the area into the
first part of the weekend. Temperatures are expected to warm out
ahead of the front into the lower and middle 80s as winds become
more southerly and warmer air tries to make a return. Timing of
the next front still looks to be later Sunday afternoon/night and
Monday. This system will have to be monitored for severe weather
potential as well as heavy rain. Hydro concerns will likely become
more evident if widespread rains develop as antecedent conditions
are now moist across much of the region.

Cooler and drier conditions follow this weather feature through
the rest of the period. Temperatures are expected to range
slightlybelow normal through midweek.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1255 AM CDT Thu Aug 17 2017

Surface low over south-central MN will continue to shift ENE into
western WI through daybreak. Rain shield will mainly affect KRWF-
KAXN early on then move thru the remaining TAF sites (except
potentially KMKT). This will keep ceilings mainly in IFR range
and, depending on rainfall intensity, have visibility between MVFR
and LIFR. In addition, sites that are near the circulation will
experience winds in excess of 30kt (and have already seen a gust
over 50kt at KRWF). Conditions will remain degraded thru mid-
afternoon then improvement will come slowly from west to east.

KMSP...Conditions likely to hit IFR prior to the morning push then
remain in IFR range through mid-afternoon. Some showers will drift
through the area from time to time this morning through around
midday before the rain shield as a whole moves off to the NE. VFR
conditions are not expected to be realized until Thursday evening.

Fri...VFR. Chance afternoon/evening TSRA. Wind W 5 kts.
Sat...VFR. Wind W 5 kts.
Sun...VFR. Chance afternoon/evening TSRA. Wind S 5-10 kts.


MN...Wind Advisory until 1 PM CDT this afternoon for MNZ065>070-

     Flood Watch until noon CDT today for MNZ041>044-047>051-054>059-



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