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FXUS63 KMPX 221124

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
624 AM CDT Thu Aug 22 2019

.UPDATE...For 00Z Aviation discussion below


.SHORT TERM...(Today through Friday)
Issued at 349 AM CDT Thu Aug 22 2019

Another benign weather day is expected as Canadian high pressure 
dominates the region. There will be some mid-level/cumulus cloud 
cover as cyclonic flow lingers, primarily from central MN across 
west central WI.

Temperatures will be akin to early to mid September normals today 
and Friday, with highs in the mid 70s and lows in the upper 40s to 
lower 50s. Winds will be light given the presence of surface high 

.LONG TERM...(Friday night through Wednesday)
Issued at 349 AM CDT Thu Aug 22 2019

Little change was made to the forecast for the long term period as
guidance remained consistent with holding off the best chance for
widespread of precipitation until Sunday night through Monday.
This will be followed by a cold frontal passage and temperatures
below normal to finish the month of August.

By Friday night, the surface high will be centered over the
Northern Great Lakes with the upper level ridge over us.
Meanwhile, the western CONUS trough will be in the process of
beginning to dig as a strong jet streak pushes ashore across the
Pacific Northwest. The trough will continue to dig southeast
across the Dakotas Saturday, making slow progress eastward thanks
to the stubborn downstream ridge and surface high. Southerly winds
will increase Saturday, especially across western MN as the
gradient tightens between the departing high and approaching

The upper jet will push the shortwave into Minnesota mainly Sunday
but there are still some timing uncertainties given model
differences at this time. Showers and thunderstorms are likely
Sunday night as the wave moves through and ahead of an approaching
cold front. CAPE and shear parameters indicate a low severe
weather threat, but could foresee a couple isolated strong to
severe storms. PWATS increasing to near 2.0" would also suggest
potential for heavy rainfall, but the front will be rather
progressive, keeping storms moving out ahead of it. 

One of the other main differences in the model guidance is the 
handling of the surface reflection of the upper trough, especially
given the merger of a pre-existing shortwave initially out ahead 
of the quicker moving trough with stronger jet support. Regardless
of the precise differences, a strengthening surface low will 
likely drift east across far southern Canada early next week, with
a cold front draped south across the Upper Midwest. At this time 
the front looks to move west to east across MN/WI on Monday. This 
low will move very slowly across northern Ontario middle of next 
week as it deepens rapidly at this point. What this means for us 
is a fairly strong push of below normal temperatures and dew 
points in from our northwest and given the very slow movement of 
the system to our north, this cool flow could persist for several 
days as we finish the month of August.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 624 AM CDT Thu Aug 22 2019

A deck of clouds circa 6-7KFT will swing across the central/eastern
part of the forecast area this morning, and then additional
cumulus cloud development is expected this afternoon. A few 
sprinkles are possible in west central WI near KEAU, but sites 
should remain dry. Ceilings will remain VFR, and then clearing is 
expected this evening. Light and variable winds increase to around
5 knots from the east/southeast by late morning, and then become 
light and variable again this eve. 

KMSP...No concerns.

Fri...VFR. Wind SE 5-10 kts.
Sat...VFR. Wind SE 10G20 kts.
Sun...MVFR/IFR possible. PM -TSRA likely. Wind S 10G20 kts.



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