Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 202335

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
635 PM CDT Sun May 20 2018

Issued at 617 PM CDT Sun May 20 2018

Updated to include 00z aviation discussion below.


.SHORT TERM...(This evening through Monday)
Issued at 303 PM CDT Sun May 20 2018

Very dry northeasterly flow associated with the area of high
pressure across central MN has done a good job of suppressing the
cloud cover to extreme southern MN. However, the shortwave to our
southwest is going to lift northeast and eventually the cloud
shield will lift northward tonight.

Modest forcing for ascent will lift north with the wave tonight,
so pops increase from south to north as time goes on. The hi-res
CAMs continue to advertise the possibility of few to scattered
showers, but the uninspiring lift and moisture in addition to
fighting off the very dry antecedent airmass, did not warrant any
higher than about 30% PoPs.

The main shortwave will lift through during the day tomorrow, but
the story will remain the same. Limited omega and instability in
the latest guidance led to lowering of the PoPs and removal of
thunder mention in the forecast for tomorrow. With the upper wave
moving through, expect highs to top out in the mid to upper 60s.

.LONG TERM...(Monday night through Sunday)
Issued at 303 PM CDT Sun May 20 2018

The main concerns in the long term are the system that could bring
showers and thunderstorms Tuesday night through Wednesday.
Otherwise, the main story in the long term is the return flow
bringing warmer temperatures back into the region. Of course, an
early look ahead to next weekend as well, which could bring some
activity to the region.

Not much has changed with the forecast for Tuesday night through
Wednesday other than to slow the onset of the precip chances
slightly. With this wave, there will be some instability to work
with with deeper moisture available, but the main jet stream is
going to continue to be locked up way to our north. Shear will be
lacking during this time so while it will be possible to get a
severe storm or two, don`t expect widespread issues.

The remainder of the week looks pretty quiet but the guidance is
showing a shortwave trough moving through next weekend. Confidence
isn`t too high being so far away but it`s interesting to see the
GFS and ECMWF both showing this wave moving through on Saturday,
potentially bringing rain through as well. Again, will see how
this evolves in the coming model runs over the next several days.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 617 PM CDT Sun May 20 2018

Conditions will remain VFR through tonight the conditions will
deteriorate from near the Iowa border and pushing north during the
day tomorrow. Ceilings will drop into MVFR range, potentially even
between 010-020 level. Isolated to scattered -SHRA will accompany
the lower clouds, but will be rather light so have only gone
between the VCSH and -SHRA mention, each with visibility no lower
than 6SM. Should precipitation coverage increase, as hinted at
within multiple runs of the HRRR, then visibility could also drop
into MVFR range but will see how this scenario evolves for later
TAFs. From this evening onward, winds will remain 10kt or less
mainly out of the southeast.

KMSP...High clouds will increase in coverage and lower through
this evening, ending up in mid-level ceilings by late Monday
morning. Isolated -SHRA from southern MN may make a run for the
terminal late morning through mid-afternoon but chances are too
low for inclusion at this point yet have been showing up
consistently in hourly short-term model runs so the potential
cannot be ignored. As such, have included a VCSH at this point and
will see how this scenario evolves and make further adjustments as

TUE...MVFR cigs early, then VFR. Wind SE 5 kts.
WED...VFR with chc SHRA/TSRA late. Wind SE 5-10 kts.
THU...VFR. Chc -tsra. Wind S 5-10 kts.




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