Area Forecast Discussion
Issued by NWS Twin Cities, MN

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091
FXUS63 KMPX 240254
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
954 PM CDT Sun Jul 23 2017

.UPDATE...
Issued at 954 PM CDT Sun Jul 23 2017

Updated to include 06Z aviation discussion below.

&&

.SHORT TERM...(This evening through Monday)
Issued at 310 PM CDT Sun Jul 23 2017

A ridge of high pressure will move overhead tonight, and east of
the region by Monday afternoon. Patchy or areas of fog is still
forecast tonight, especially over east central and central
Minnesota, as well as west central Wisconsin as this is where most
of the precipitation has occurred in the past few days. Monday
will be similar to today but less cloud cover and slightly higher
temperatures. Humidity levels will remain low during this period.

.LONG TERM...(Monday night through Sunday)
Issued at 310 PM CDT Sun Jul 23 2017

No major changes to the extended period as the best chance of
widespread precipitation occurs Tuesday and Wednesday. Timing
remains close to previous model forecast as the bulk of the
moisture and lift occurs in northern Minnesota through Tuesday
afternoon, but as a cold front sags southward Tuesday evening,
most of central and southern Minnesota, as well as west central
Wisconsin will see showers and thunderstorms develop and spread
south and east.

As for severe weather parameters, it remains questionable on
severity due to timing of the main thunderstorm activity occurring
Tuesday night, early Wednesday. If the front slows, Wednesday
afternoon could be prime along the Iowa, Minnesota border as both
instability and wind shear values will be adequate for large hail
and damaging winds. As with previous discussions, Highs PWAT
values and the possibility of training thunderstorms Tuesday
night, could lead to flooding problems. This is mainly for areas
that has received the heaviest rainfall over the past week.

Past Wednesday, models remain consistent with a somewhat dry
period, but another cold front moving southward late next
weekend.

The mean flow remains conducive for no big warm-ups or cool
periods. It will be the typical warm and humid summer in the Upper
Midwest with highs in the 80s and lows in the 60s. The highest
temperatures and humidity levels will occur in the warm sector
Tuesday afternoon. Although models have trended a bit cooler than
in previous runs, dew points rising into the 60s/lower 70s and
highs approaching or exceeding 90 degrees will lead to heat
indices of 95 to 105 degrees Tuesday afternoon. The winds will be
from the south-southwest which is a good component for downslope
conditions along the lee of the Buffalo Ridge. This area could see
highs in the mid/upper 90s if more sunshine develops.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 954 PM CDT Sun Jul 23 2017

Made no substantive changes to earlier forecast. Lingering
stratocu over the eastern portion of the area is taking a bit
longer to dissipate than anticipated than expected, so will need
to keep an eye on KEAU (and perhaps KRNH) at the start of the
period for ceilings near MVFR category. Otherwise, high pressure
will move east through the period, with winds veering around to
the southeast. Still some concern for a bit of fog later, but with
mixed signals in the guidance and potential development still
several hours away chose to leave things as is.

KMSP...Only concern would be some lower VFR ceilings toward the
end of the period as precipitation tries to work into western
Minnesota. It`s possible this evolution could be faster than
currently forecast, so that would be the one thing to keep an eye
on in updated guidance.

/OUTLOOK FOR KMSP/
Tuesday...MVFR possible with a chance of showers and
thunderstorms. South wind 10 to 20 kt.
Tuesday night...MVFR expected with showers and thunderstorms
likely, brief IFR possible. South wind 10 to 20 kt.
Wednesday...MVFR possible with a chance of showers and
thunderstorms. Southwest wind 10 kt or less becoming west.
Wednesday night...VFR. West wind less than 10 kt becoming
northwest.
Thursday...VFR. Northwest wind 5 to 10 kt becoming north.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...
SHORT TERM...JLT
LONG TERM...JLT
AVIATION...



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