Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 270346

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1046 PM CDT THU MAY 26 2016

.UPDATE...for 06z aviation discussion below


.SHORT TERM...(This evening through Friday)
Issued at 245 PM CDT Thu May 26 2016

An upper level trough centered over the four corners region and
associated surface low developing in the panhandle region is the
culprit behind widespread thunderstorm activity ongoing across the
Great Plains this afternoon. This system is expected to slowly
progress north east through tomorrow, and bring precipitation
back into our area overnight through tomorrow. For tonight,
current thunderstorm activity is expected to congeal into an MCS
this evening and primarily impact northern MO and much of IA. As
it turns east through the state of Iowa, it is progged to weaken
some, and shower and thunderstorm development is expected to pop
in southern Minnesota primarily after midnight. The main change to
the forecast was to slow down the onset of the precipitation.
Expect the precip to slowly develop and expand northward,and it
will likely be 3AM or after by the time it is better organized and
advancing toward the Twin Cities Metro. This activity is not
expected to be severe at this time. Best LI`s are slightly
negative suggesting only modest instability. MUCAPE values should
top out around 500-1000 J/Kg. Any storms that venture into our
area should be elevated and deep layer shear is rather weak.

For Friday, lowered the POPs across western MN as the activity
there now looks to be more scattered in nature. The main organized
area of showers and storms will track along and east of a line
from roughly St. Cloud to Mankato, including the Twin Cities and
west central Wisconsin. Continued likely pops in this area, and
again the severe weather threat is low. This area of precip should
advance north of our forecast area by the afternoon with only
scattered to isolated showers and storms possible during the

.LONG TERM...(Friday night through Thursday)
Issued at 245 PM CDT Thu May 26 2016

The large scale weather pattern will evolve some through the period,
but things will remain unsettled as we see southwest upper flow
become more zonal, but with an embedded upper trough over north
central US/southern Canada by Thursday/Friday time frame.
Unfortunately, identifying dry periods in the forecast will be
tough, especially the farther we go out in time given some timing
and amplitude differences in the model guidance. Overall, the models
are fairly similar with respect to the large scale, so stuck close
to a consensus forecast through the period.

Maintained chance to likely PoPs for Friday night into Saturday
night with the boundary in the vicinity and ample instability still
in place as several shortwaves work through the region. Sunday
continues to look like our best shot at mainly dry conditions across
the area, with the boundary shifting east and a weak surface ridge
working in from the west. Best chance of any precipitation on Sunday
will be over the eastern portion of the area, so kept chance PoPs
there, with slight chances out west given some lingering instability
and the possibility of widely scattered diurnal activity.
Precipitation chances look to increase from west to east later
Monday into Tuesday as a warm front lifts north through the region
and the next surface low/trough moves into the northern Plains. The
GFS and ECMWF show some fairly significant differences at this
point, with the ECMWF being more eager to push a cold front through
by Wednesday morning, and the GFS waiting until Wednesday night.
Favored the ECMWF timing, but did keep some low PoPs going into
Wednesday night given the uncertainty. Some low PoPs are still
mentioned on Thursday given the previous forecast and overall slower
solutions in previous runs, but if current trends persist, subsequent
forecasts may be able to dry things out for Thursday.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1055 PM CDT Thu May 26 2016

Arrival timing of the showers and thunderstorms working north from
Iowa and Missouri continues to trend later. Still expect activity
to lift north into the area during the morning hours, but most
sites should stay dry until after 12z. Then expect shra/ts to
affect sites until 21z. Conditions when convection is occurring
may drop to MVFR, but otherwise primarily VFR conditions are
expected. Southeasterly winds around or below 10 kts prevail.

Primary window for thunder looks to be from 14-18Z with
showers beginning as early as 11Z. MVFR conditions are possible
with the stronger showers and thunderstorms.

Sat...Chance MVFR. TSRA Likely. Wind SE 5-10 kts.
Sun...Mainly VFR. Slight chance MVFR/TSRA. Wind SW 5-10 kts.
Mon...Chance MVFR. Chance of TSRA. Wind S 5 kts.


.MPX Watches/Warnings/Advisories...


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