Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 272053

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
353 PM CDT SAT AUG 27 2016

.SHORT TERM...(This evening through Sunday)
Issued at 353 PM CDT Sat Aug 27 2016

The short term concern remains thunder/severe weather threat

The latest mesoscale analysis shows a narrow corridor of instability
of 500-1000 j/kg over the far Northwest corner of the cwa. Mid
level lapse rates around 7 c/km and 30-40 kts of shear is enough
to generate a few strong storms along the upper trough axis as it
is moving over northwest MN. Latest HRRR forecast radar shows
this may affect the nw fringe of the cwa through 02z.
Otherwise...models depict rather abrupt moisture surge into the
southwest mainly after midnight. This should generate some
accas...eventually thunder into that region of the cwa shortly
thereafter and then spread east through 12z. This will continue
into the morning and spread into the northeast cwa into the
afternoon. Difficult to discern how far north to go with lower end
pops and how long it will continue into Sunday.

It looks like we will maintain clouds through the night and into the
day Sunday...along and north of the warm front. This will limit
overall heating to the northeast but instability increases
dramatically along and south of the front. The only real limiting
factor to redevelopment of storms along the boundary will be the
rising heights/anticyclonic flow over the western great lakes. The
GFS redirects moisture back to the northwest and this may be area of
initiation late afternoon/evening and follow east and south along the
front. Temperatures should warm through the 80s south of the
front...and a 90 degree reading is not out of the question if enough
sunshine is seen. Dewpoints rise to around 70 by late afternoon
south of the front as well.

.LONG TERM...(Sunday night through Saturday)
Issued at 353 PM CDT Sat Aug 27 2016

Main concern is storm threat Sunday night through Monday night.
Previous paragraph mentioned redirection of moisture tomorrow, and
significant moisture really surges into the area Sunday evening.
There is also an extensive ribbon of subtropical moisture
currently stemming from the southern tip of Baja California to the southwest
Kansas, and storms have been erupting throughout said area this

Meanwhile, several deterministic models point to a subtle short
wave moving across North Dakota tomorrow afternoon and early
evening. This moves across northern MN Sunday night. Nam is the
most aggressive with showing a southeast movement tomorrow night,
with maybe even a mesoscale convective complex. The other models
have a hint of this as well. Therefore have maintained decent
pops from central MN into west central WI. With the likelihood of
warm rain processes with the tropical plume, and will have to
watch if heavy rain develops into our area. Another subtle short
wave drops ese Monday afternoon and evening, so have kept pops
through Monday night.

Upstream ridge edges closer to the area on Tuesday, with resultant
dry nw confluent flow over MN/WI. Ridge does not move across MN
until Thursday, so have dry weather Tue-Thu. Broad sw flow resumes
Thursday night, so thunderstorm pops return to the forecast then,
and persist through Saturday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1225 PM CDT Sat Aug 27 2016

Initial rain shield lifting northeast around 32 kts. Should exit
the taf sites within an hour or so. Then we will likely see a
period of mvfr cigs over the east and south into the afternoon. It
may break out briefly in spots...but believe overall trend will
be for more stratus to lift north/develop into the evening. Went
ifr/lifr developing over eastern areas with light winds and some
breaks in clouds. Moist boundary layer should be enough to
generate the stratus and fog overnight...ahead of developing warm
front. This afternoon...still have possibility of tsra affecting
the northwest area into the afternoon/evening before dissipating.
Then another shot of thunder possible to the southwest as low
level waa develops along the front. This may affect krwf after
06z. After this afternoon...that appears to be the only area to
see rain until 18z Sun. Light winds remain over the eastern areas
with high pressure becoming se-s and increasing into Sunday.

KMSP...Rain exiting area now. Mvfr cigs should remain into the
afternoon before breaking out toward 00z sun. Then expect some
stratus/fog to lift/develop over the region overnight perhaps
going ifr after 10z or so. Looks like thicker clouds to remain
over the southwest well into the night. Some threat of shra/tsra
into the afternoon along surface front. But timing still in
question so will leave out for now.

Sun nite...vfr. Slight chance afternoon mvfr -TSRA. Wind S 5-10
Mon...VFR. Chc -tsra. Wind S 5-10 kts.
TUE...VFR. Wind light and variable.


.MPX Watches/Warnings/Advisories...


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