Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 220354

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1054 PM CDT THU JUL 21 2016

Issued at 1052 PM CDT Thu Jul 21 2016

Updated to include 06z aviation discussion below.


.SHORT TERM...(This evening through Friday)
Issued at 310 PM CDT Thu Jul 21 2016

Early morning convection that caused significant wind damage
across west central Wisconsin during the pre dawn hours, had
moved rapidly into the Midwest region this afternoon. The residual
outflow boundary and weak front across parts of central Minnesota,
and into west central Wisconsin that was associated with the
earlier convection, continued to develop scattered showers and
thunderstorms along it through the morning, and into the early
afternoon. Surface base CAPEs above 5000 j/kg and weakening cap
allowed for a few strong storms to develop near Red Wing around 2
pm. Other storms were non-severe continued to develop in this
weakening cap regime.

Although models have not been helpful today with the ongoing
activity, there remains enough confidence to include isolated
thunderstorms along the weakening front as it sags southward into
northern Iowa this evening. Based on the instability and wind
shear values, some severe storms are still possible through the
early evening, however, any storms that develop will be isolated.
There still remains some uncertainty with chances of precipitation
overnight, and especially Friday afternoon as the aforementioned
front will washout in northern Iowa Friday morning, before
returning northward Friday night as a warm front. There is also a
weak short wave evident across the central Rockies which may help
to initiate more thunderstorms Friday as it interacts with the
washout front. Will continue to have low percentages along the
Iowa border overnight, but kept chances out of the forecast on
Friday. This needs to be watched for possibly increasing chances

As for the heat warning continuing in far southern Minnesota,
including the Twin Cities; due to the lack of cooler air aloft
behind the weak front today, there is still a good likelihood of
heat indices rising above 100 degrees Friday afternoon, especially
along the Iowa border, northwest into west central Minnesota.
This is based on dew points returning into the low to mid 70s,
with high temperatures similar to this afternoon in the upper 80s
to mid 90s.

.LONG TERM...(Friday night through Thursday)
Issued at 245 PM CDT Thu Jul 21 2016

The long term concerns are timing of next convective event and
severe weather/flood threat associated.

It appears the front will begin to return north as a warm front
late friday night across the dakotas. Timing of upper trough has
slowed a bit...perhaps by 6 hours or this may leave much
of Friday evening dry. Will continue to bring in chance pops over
the wet late in the night as waa/destabilization increases.

This trough and associated front drives east Saturday and Saturday
night. Will continue the likely pop trend Saturday afternoon and
Saturday night. Some threat of ongoing convection early Saturday
which may limit destabilization some...but severe weather threat
does remain for this deep layer shear and instability
remains quite strong. Also...PW`s increase to around 2 inches
along/ahead of the front and any organized convection should
produce torrential rains. Will have to monitor this
trend...although limiting factor will be overall progressive
movement of the front.

Drier air moves in following this front through Monday night with
the next convective threat arriving Tuesday through Wednesday as
the fast zonal upper air pattern continues across the northern
states. Temperatures are expected to remain warmer than normal
through the period as well.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1052 PM CDT Thu Jul 21 2016

Very few aviation concerns as the earlier convection over
southwest MN has diminished while the activity over northeastern
Iowa will continue moving away to the southeast. No further
convection is expected over central and southern MN into wets
central WI. High SCT clouds will remain throughout the period.
Winds will generally remain 5kt or less with varied directions.

KMSP...No significant weather concerns.

Sat...VFR early then chances increase for MVFR-IFR late. TSRA
likely late. Wind SE 5-10 kt.
Sun...VFR. Winds NW 10-15 kt.
Mon...VFR. Winds NW 5-10 kt.


.MPX Watches/Warnings/Advisories...
WI...Excessive Heat Warning until 7 PM CDT Friday for WIZ024-026.

MN...Excessive Heat Warning until 7 PM CDT Friday for MNZ054-056-



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