Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 211712
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1212 PM CDT THU JUL 21 2016

.SHORT TERM...(Today and tonight)
Issued at 513 AM CDT Thu Jul 21 2016

Concerns early this morning have been with strong to severe
thunderstorms moving across the northern and eastern CWA overnight.
The storms originated back in ND last evening. Wind gusts in the
40 to 50 mph range have been common along the leading edge of the
storms. We`re still dealing with a cluster of storms over central
MN that have a large hail threat. Going forward this morning, we
believe that skies will clear with the mid level cap reasserting
itself. However, the storms early this morning have certainly
taking their toll on the overnight lows...knocking temperatures
down into the 60s across central MN with near 70 in the Twin
Cities. This has lowered our confidence on being able to achieve
highs in the middle to upper 90s this afternoon with quite a bit
of recovery that needs to take place. However, it`s too soon to
throw in the towel with our heat headlines with peak heating not
taking place until around 5 pm. Hence, the heat headlines remain
in place with afternoon heat indices reaching 100 to 110 degrees.

This brings up another concern/problem for late in the day/evening.
A cold front will be sagging slowly south into central mn and
adjoining areas of west central WI late this afternoon. Several
CAMS are showing thunderstorms developing along the front. We
added some small pops to account for this but pops may need to be
raised much higher after seeing what occurred overnight even
though mid level temperatures were in the +14 to +16 degree range
over a wide area. Can`t really say it`s going to be cooler tonight
after the storms this morning, but lows tonight are progged from
the lower 60s in central MN to the lower 70s in southern MN.

.LONG TERM...(Friday through Wednesday)
Issued at 513 AM CDT Thu Jul 21 2016

Excessive heat on friday and severe thunderstorms Saturday into
Sunday are the main concerns in the long term.

Friday will mark the end of the heat wave with highs topping out
in the lower to middle 90s. Fortunately the 70+ degree dew points
are expected to be confined to south central MN with middle to
upper 60s to the north. This yields heat indices Friday afternoon
in the 100 to 105 range across south central and portions of west
central MN with around 100 degrees for the Twin Cities. Therefore,
the excessive heat warning for these areas is still valid and will
remain in effect. Areas of central Minnesota and west central
Wisconsin have heat indices in the lower to middle 90s which is
borderline heat advisory criteria. However, if the high
temperature forecast is too warm on Friday, then all heat indices
values will be lower. Hence, left the headlines alone for now.

Thunderstorms will return on Saturday as a warm front lifts
northeast across the FA. The timing is a little slower and it may
take until afternoon until thunderstorms get underway. Heading
into the evening and overnight hours, a cold front will be pushing
in from the Dakotas with more thunderstorm development likely. Any
of the storms Saturday and Saturday night could be severe. In
addition, PWAT values will climb back above 2 inches and heavy
rainfall will likely occur with some of the storms leading to a
flooding threat.

Seasonal temperatures will prevail next week with thunderstorm
chances returning Tuesday and Wednesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1210 PM CDT Thu Jul 21 2016

Main aviation concern this afternoon is isolated thunderstorm
development along a weak front sagging southward across southern
Minnesota and west central Wisconsin. There was an area of
showers and thunderstorms across central Minnesota and into west
central Wisconsin early this afternoon, but has weakened
considerably and will likely weaken this afternoon before more
develop toward 22-24z. However, there remains the weak front
which will likely cause a spotty storms to develop as early as
18-21z, especially across far southern Minnesota, and portions of
west central Wisconsin where instability is highest. Will adjust
tafs based on current radar trends. However, the best scenario is
to use VCTS. Later this evening, the weak front should be far
enough south to limit any thunderstorm activity in MPX forecast
area. Winds will become north-northeast by late afternoon/evening,
with a more east- southeast flow developing Friday morning.

KMSP...

Not much to add with isolated thunderstorms possible after 18z.
Any thunderstorms that develop should be brief with visibility
lowering to IFR at times in the heavier showers.

/OUTLOOK FOR KMSP/

Fri...VFR. Chc -TSRA late. Wind E-SE 5 kt.
Sat...VFR. Chc -TSRA late. Wind S-SE 5-10 kt.
Sun...VFR. Winds NW 10-15 kt.

&&

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

     Excessive Heat Warning until 10 PM CDT this evening for
     WIZ014>016-023-025-027-028.

MN...Excessive Heat Warning until 7 PM CDT Friday for MNZ054-056-
     060>070-073>078-082>085-091>093.

     Excessive Heat Warning until 10 PM CDT this evening for
     MNZ041>045-047>053-055-057>059.

&&

$$

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



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