Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 181807

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
107 PM CDT MON JUL 18 2016

.SHORT TERM...(Today and tonight)
Issued at 327 AM CDT Mon Jul 18 2016

Clear skies, light winds, and temperatures in the 60s have led to a
rather pleasant morning across the Upper Mississippi Valley. Surface
high pressure will remain overhead today with the light winds and
mostly clear skies expected to continue. Guidance is tightly
clustered with temperatures and dew points today.

Thunderstorm complexes have formed along a boundary overnight from
Iowa eastward to Ohio. That front will begin to lift north later
today. A LLJ in conjunction with a disturbance tracking east around
the building central Plains ridge will produce more thunderstorms
along that boundary tonight. The focus for these storms appears to
be mostly from southern SD eastward to southwestern MN and southeast
into Iowa. Some of it may brush our counties south of the MN river,
which wouldn`t be the best situation due to the multiple inches of
rain that fell in that area Saturday night. Also, training
convection would appear likely where that band sets up given the
orientation of it and the LLJ. Increasing pwats toward 1.75 inches
will lead to heavy rainfall rates. Increased pops across the
southwestern CWA.

.LONG TERM...(Tuesday through Sunday)
Issued at 327 AM CDT Mon Jul 18 2016

Heat and humidity. That is the main concern in the long term
period and we`ve issued an Excessive Heat Watch starting Wednesday
afternoon and lasting through Friday for most of southern

Heat wave remains on track as large upper ridge builds in mid week
with a warm front lifting through by Wednesday. Widespread
temperatures in the mid to upper 90s is likely, and went ahead and
raised dew points a few degrees on Wednesday, Thursday, and
Friday. Moisture connection to the gulf will be wide open and
dewpoints in the mid to upper 70s are expected, with some in the
80s not out of the question. At this time, southern MN looks to be
within the core of the highest dew points with this pattern. With
the increase in dew points alone, forecast heat index values were
raised to over 100 degrees across the board Wednesday, 105 to 110
Thursday (higher values locally will be possible), and around 105
on Friday mainly across far southern MN and western WI. Overnight
low temperatures were also raised and temperatures only falling to
the mid to upper 70s Wednesday night and Thursday night will not
provide much relief to those without air conditioning. We urge
everyone to exercise caution if spending time outdoors Wednesday,
Thursday, or Friday.

In terms of precip potential in the long term period, we`ll have a
few chances of scattered showers and storms to develop. The
beginning of the period on Tuesday morning will likely have precip
working across southern MN...but there are questions in terms of
spatial coverage so continued chance pops for that time period as
shortwave rides over the top of the ridge and through the area.
Tuesday night will bring strong theta-e advection with a theta-e
ridge working in, so continued to advertise pops for this period.
The really warm air and effective cap will reach western MN
Wednesday, while western WI will still have a chance for
thunderstorm development through the day. With the thermal ridge
fully in place Thursday, continued a dry forecast. Precip appears
possible mainly to our north overnight, where the temperatures
aloft aren`t quite as warm. The GFS/EC are both indicating an MCS
developing and moving through northern MN Friday night, which
could affect parts of southern MN depending on the timing of the
cool front. Behind the front, temperatures and dew points will
drop to more comfortable levels.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 107 PM CDT Mon Jul 18 2016

Few concerns this period with main change coming from the fact
that high pressure overhead today will be off to our east on
Tuesday, meaning we will end this period with southeast winds. Any
thunderstorm activity ahead of the warm front tonight into Tuesday
morning looks to remain southwest of the MPX terminals. Only
possible issue is at RWF, which may have MVFR cigs tomorrow
morning as the warm front approaches SW MN. SREF probs say we
stay VFR though, to kept RWF VFR.

KMSP...Will have variable winds basically through the rest of
tonight. Otherwise, high confidence in a dry and mainly clear TAF

Wed...VFR. Chc -TSRA. Wind S at 10g20kt.
Thu...VFR. Wind SSW at 5-10kts.
Fri...VFR Chc -TSRA late. Wind SE 5 kt.


.MPX Watches/Warnings/Advisories...
MN...Excessive Heat Watch from Wednesday afternoon through Friday
     evening for MNZ041>045-047>070-073>078-082>085-091>093.



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