NWS Forecast Discussion

FXUS63 KMPX 020505

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1205 AM CDT Mon Aug 2 2021

.SHORT TERM...(This evening through Monday night)
Issued at 249 PM CDT Sun Aug 1 2021

Smoke and haze conditions have greatly improved across the area with
only far western Minnesota still seeing some hazy skies. To the
east, a Cu field has developed but there are still plenty of patches
of blue sky, which is a welcome sight. While smoke aloft will push
back eastward overnight tonight, near surface smoke looks to remain
minimal. Because of this, have taken widespread surface smoke/haze
out of the forecast through Monday night. Additionally, the MPCA has
improved the air quality index from Red/Unhealthy to Orange/Unhealthy
for Sensitive Groups for the Minnesota portion of our CWA. An Air
Quality Alert remains in place through the short term period.

Other than the smoke/haze concerns, the short term forecast will be
characterized by pleasant temperatures a few degrees below normal and
dew points in the low 50s. Surface observations as of 2:30pm have
the entire CWA at 80 degrees or less with comfortable dew points in
the upper 40s to low 50s. Tomorrow will be a few degrees warmer as a
ridge slides further east. Added very low PoPs across our western
Wisconsin counties as a weak shortwave may lead to a few showers
during the afternoon. Other than that, things remain quiet with high
pressure in place.

.LONG TERM...(Tuesday through Sunday)
Issued at 249 PM CDT Sun Aug 1 2021

High pressure continues to dominate on Tuesday, so dry conditions
will continue early this week. Smoke will clear on Tuesday as flow
throughout the atmosphere moves away from Canada, cutting off the
smoke supply. With this change in flow though the weather could also
become more active. This change in atmospheric flow will result in
more heat and moisture advecting into the Upper Midwest. This will
increase temperatures to near 90 by the end of the week with dew
points expected to be in the 60s. So nothing tropical, but still
much warmer and more humid than our current air mass. This will lead
to increased precipitable water values in the 1 to 1.5 inch range,
which is right around normal for this time of year. This does
however make rain more likely when the appropriate forcing is
present. With a shortwave passing the Upper Midwest late Wednesday
into Thursday and another possible over next weekend those periods
will be our next chances for rain. Most GEFS members are clustering
in the 0 to 0.5 inch range for total QPF during this period so while
this rain could be beneficial it won`t make much of a dent in
Minnesota`s drought. The increase in heat and humidity will provide
for some increased instability increasing chances for thunderstorms.
Exactly how unstable we get, what kind of cap we get (this played a
big role last week), available shear, and the position of surface
boundaries will all play a role in determining the risk for any
stronger storms. So in summary, smoke clearing this period with
warming temperatures and chances for showers/thunderstorms.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1205 AM CDT Mon Aug 2 2021

Concerns are smoke and possibly patchy ground fog tonight. High
pressure along the MN/SD border will drift across the area tonight,
with return southwest flow setting up for Monday. Air mass has been
quite dry so widespread fog is unlikely, but added a fog tempo group at
KSTC and KEAU where patchy fog is not uncommon in these setups.

The surface smoke now in west central and southwest MN has begun
drifting east, but with weak low level winds, it may take some time
for any lower visibilities to occur. Have kept the forecast at 5-6sm
for western MN the rest of tonight, then gradually spreading into
central/eastern MN and far western WI midday, and later Monday in
west central WI.

KMSP... No additional concerns.

Tue...VFR. Wind SW 5-10 kts.
Wed...VFR. Wind SW 10-20 kts.
Thu...VFR. Wind SW 10-20 kts.





NWS MPX Office Area Forecast Discussion

Script by Ken True @Saratoga-Weather.org