Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 261101

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

.SHORT TERM...(Today and tonight)
Issued at 430 AM CDT Thu May 26 2016

Scattered storms overnight eventually congealed over southern MN
into a nice MCS that will be working into southern WI this
morning. In its wake, we have seen a cold front work into MN, with
dewpoints in the upper 40s and lower 50s being observed in western
MN. Short wave helping generate the MCS will move off into WI as
well this morning and its wake, we will be seeing H5 height rises
through the afternoon. Despite the height rises and associated
subsidence, we will see thunderstorms redevelop this afternoon,
with models showing MLCAPE increasing to over 3000 j/kg out ahead
of it. The question of the morning is where does this front end up
this afternoon. The RAP has the southern bound with the front
getting down to about Omaha over to the SW corner of WI. The NAM
is the northern outlier, with the front only getting to about a
Fairmont to Eau Claire line. The NCAR ensemble members show a
similar spread in frontal position. Our current forecast favors
the southern solution, with a dry forecast through the afternoon
for most of the MPX area. If the more northern solution works out,
then we will see storms refire around 21z down in south central
MN, with the threat for severe weather existing as well.

Tonight, we still have likely PoPs building north through the
night, though we did slow down this push north through the night.
This increase in PoPs is in response to the next short wave coming
at us from the central Plains, which will quickly bring the cold
front back north as a warm front. As the warm front lifts north,
expect showers and thunderstorms to spread back north with it.
Still a large degree of spread in models with where convection
ends up, as between now and then we will likely see a couple more
MCSs to our south. One this afternoon in Iowa along the front,
while we should have an MCS coming at us from Nebraska tonight. So
the fate of these needs to be decided before we get a better
handle on when/where convection will be tonight, but the large
scale forcing with the warm front lifting back north supports
bringing back the likely PoPs from southwest MN toward the Twin
Cities, even if there is large spread in the CAMs with how much
and where convection is tonight.

.LONG TERM...(Friday through Wednesday)
Issued at 430 AM CDT Thu May 26 2016

Friday through Saturday night: Forecast Confidence - Medium

The upper low over eastern Colorado and western Kansas will take
its time ejecting northeast across the Upper Midwest during this
period. Lead wave vorticity maxima and a warm front lifting north
Friday will generate periods of showers and thunderstorms across
the region. In this regard, the forecast has a high confidence
level. However, timing of these complexes is difficult at best
and will depend on MCS development today across Iowa and Nebraska,and
how it will impact the arrival of the warm front. Maintained high
pops through the first half of the weekend with a warm, humid,
unstable airmass capable of producing thunderstorms easily.

Sunday through Monday: Forecast Confidence - Medium

Slight ridging will be in place for Sunday and Monday, but models
seem to generate quite a bit of precip across the central Plains
and Mid Missouri Valley. Am a bit skeptical of this given no upper
support and if anything pop up storms would be isolated to
scattered in nature. Kept pops low - 20 to 30 percent, but
eventually we may be able to go dry in many locations.

Monday night through Wednesday: Forecast Confidence - Low

Models differ quite a bit in the evolution of the next system
originating from the Pacific Northwest early week. ECMWF takes it
due east along the Canadian border and brings mainly one round of
thunderstorms with the cold front. GFS on the other hand brings
several periods of thunderstorms much like the nearer term pattern
with the slower upper low taking a detour across the central


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 601 AM CDT Thu May 26 2016

The first 12 hours of the TAF period will be quiet as a cold front
settles south of the area. Tonight however, this cold front will
come back as a warm front, with SHRA/TSRA chances increasing as a
result. Did favor a RAP/GFS timing for bringing shower chances
back, which resulted in delaying their arrival by several hours in
the TAFs, with activity likely not reaching STC/AXN until after
12z Fri. Before activity reaches here tonight, we should see a
couple of MCSs develop to our south, which will impact what
activity coming back at us tonight will look like, with confidence
in timing and placement of any activity tonight being low.

KMSP...High confidence in the forecast through about 3z, but after
that, the warm front will start lifting back toward the Twin
Cities, with the threat for SHRA/TSRA increasing as well. Little
confidence on when and where convection will be from 3z onwards,
so kept shower mention fairly broad with the VCSH mention, while
the PROB30 group highlights when the GFS shows the warm front
moving through.

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


.MPX Watches/Warnings/Advisories...


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