Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 220509

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1209 AM CDT Tue May 22 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 246 PM CDT Mon May 21 2018

The secondary trough will continue moving through the area this
afternoon and tonight, with plentiful low level moisture and
modest lift persisting but lifting north of the area later this
evening. Scattered showers will continue slowly lifting north, and
QPF values will be very insignificant, generally less than a tenth
of an inch.

With the increased low level moisture and winds becoming quite
light tonight, expect fog to develop overnight. Western MN will be
the most susceptible to potentially dense fog, especially in the
wake of the showery activity that moved through today.

The trough will slowly depart to our east tomorrow as gradual
clearing is anticipated to ensue late in the day. Highs tomorrow
should rebound into the mid to upper 70s.

.LONG TERM...(Tuesday night through Monday)
Issued at 246 PM CDT Mon May 21 2018

The main concerns in the long term period are the rain amounts for
Wednesday through Thursday night and the chance for severe weather
Thursday/Thursday night. Split upper level flow does present a
problem for shear parameters, but instability and moisture will be
ample Thursday/Thursday night.

By tomorrow night, the next shortwave will be quickly approaching
from the southwest with showers and thunderstorms expected to
spread into southwestern MN overnight into Wednesday morning. An
increasing LLJ will provide ample low level moisture convergence
and lead to enhanced lift, tapping into some modest instability.
Precipitable water values will increase to about 1.5", maybe
slightly higher.

The latest guidance for Thursday holds off convective initiation
across western MN to Thursday night as the shortwave arrives from
the west, steepening the lapse rates quickly as mid/upper levels
cool. MUCAPE values around 3000 J/kg will be ample to produce
strong to severe thunderstorms, but shear parameters are weak,
particularly in a deep column, which limit supercell potential.
More than likely, multicell clusters are possible and cold pool
development could lead to forward propagating clusters. Some
severe hail could be possible with that amount of CAPE, but with
the lack of shear, don`t expect widespread severe weather at this
time. Continue to monitor for the latest updates.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1210 AM CDT Tue May 22 2018

Main aviation concern over the next 6-9 hours is how dense the fog
becomes in southwest/south central, and portions of west central
Minnesota as skies clear. Since 10 pm, skies cleared in the far
southwest part of Minnesota and fog formed quickly and led to
vsby to 1/4SM or less. This will be the concern at KRWF early as
skies clear by 8Z. This is also the worst area in terms of
LIFR/VLIFR conditions in the next 6 hours. Elsewhere in south
central/central Minnesota, including KMKT/KAXN TAF sites will see
IFR, or LIFR during the morning hours, and still MVFR/IFR
conditions across the rest of MPX TAF sites through mid morning.
Cigs should begin to lift after sunrise, with VFR conditions by
15-18z. Winds will be light from the southeast/east through most
of the TAF period.


High confidence of MVFR cigs, with IFR cigs at times before 15z
this morning. Fog will not be as widespread as cloud cover should
hold through the night. Worst vsby will occur around sunrise and
may drop temporary to IFR. Otherwise, VFR conditions will develop
by 15-18z with a light southeast wind.


WED...Mainly VFR. Chance SHRA/TSRA with MVFR. Wind SE 5-10 kts.
THU...Mainly VFR. Chance SHRA/TSRA late. Wind S 10 kts.
FRI...Mainly VFR. Chance SHRA/TSRA late. Wind SW 5-10 kts.




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