Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 301019

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
519 AM CDT Sat May 30 2020

.UPDATE...For 12Z Aviation discussion below


.SHORT TERM...(Today through Sunday)
Issued at 328 AM CDT Sat May 30 2020

Surface high pressure will slide across the region today, while
northwest flow continues aloft between deepening troughs over the
eastern and western CONUS. Despite mostly sunny skies, weak cold
air advection will hold temperatures in the 60s for highs. Lows
tonight under clear skies and light winds will be chilly, in the
upper 30s to mid 40s.

On Sunday, surface high pressure slides off to the east and the
mid-level ridge builds toward the Upper Midwest. Temperatures
respond by moderating 5-8 degrees, with highs in the low to mid
70s anticipated.

.LONG TERM...(Sunday night through Friday)
Issued at 328 AM CDT Sat May 30 2020

Sunday night will be the start of our warming trend and will last
through the extended period. The main concerns and uncertainties are
related to timing/extent of the precipitation by midweek, and how
strong will the ridge become or weaken as a series of disturbances
move along the northern edge of this ridge.

Late Sunday night and into Monday morning seems almost certain that
an area of warm air advection shower/storm activity will develop.
Currently, percentages range from 30 to 50% which may increase over
the next 24-36 hours as models get closer to consensus. Severe
weather parameters are too weak to indicate anything more than
general thunderstorms.

By Monday evening, any precipitation would be east of Wisconsin as
the ridge continues to build northward across the Upper Midwest.
Differences in the GFS/EC occur Tuesday as the surface front moves
southward or becomes stationary. The EC continues to be more
progressive with the frontal boundary and moves it farther southward
over Iowa vs. the GFS. This difference brings a strong correlation
between the wetter GFS over southern Minnesota, vs the drier EC.
This will also have a significant impact on temperatures which
currently are approaching or exceeding 90 degrees in some locations
in southern Minnesota. As with the previous discussion, the
differences in the models are related to the upper jet structure
which the EC has a more pronounced jet across Minnesota vs. the GFS
across southern Canada. By Thursday both the EC/GFS show the frontal
boundary across the central plains which should limit any widespread
precipitation across Minnesota or Wisconsin. By the end of the week,
the atmosphere returns to a southerly flow and a better chance of
showers/storms develop.

Confidence is still quite high that next week will have above normal
temperatures, but the severity of these temperatures are more
problematic due to the chances of precipitation by midweek.

Another aspect to Tuesday/Wednesday weather system and the
differences in the frontal location, is the chance of severe
thunderstorms. Due to the EC solution of the front much farther
south, instability is weak and confined to Iowa. The northern
frontal solution of the GFS has much higher instability parameters
and would like see a few severe storms if they could develop in a
strongly capped environment. Either way it needs to be watched.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 520 AM CDT Sat May 30 2020

Mostly sunny skies and light north-northwest winds are expected
through the period.

KMSP...No concerns.


Mon...VFR with a chance of MVFR/TSRA. Wind SE 10-15 kts.
Tue...VFR. Wind WSW at 5 kts.
Wed...VFR with a chance of MVFR/TSRA. Wind NW 5-10 kts.




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