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FXUS63 KMKX 261408
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
908 AM CDT Wed Sep 26 2018

.UPDATE...

Clouds are beginning to build across the west as the upper level
trough works its way through. Between diurnal heating and
continued cyclonic flow aloft, we should see a decent cu deck by
mid day. Temps are still on track to top out in the low 60s.

&&

.MARINE...

West winds will remain breezy across the nearshore waters today,
but have diminished below Small Craft Advisory levels, and have
cancelled the advisory an hour early. With offshore flow, wave
action will be minimal.

Winds will become southwesterly and increase late tonight and
Thursday, with gales looking increasingly likely for the northern
half of the lake on Thursday and Thursday afternoon. Another Small
Craft Advisory will likely be needed for at least a portion of the
nearshore waters as well. Breezy conditions will continue into
Friday, before high pressure builds south across the area on
Saturday.

&&

AVIATION(12Z TAFS)...

No change from the previous discussion. VFR conditions will
prevail through the TAF period. Clear skies this morning will fill
in with a sct-bkn CU deck around 4-5kft. Those clouds will clear
out by sunset. Gusty northwest winds this morning will back to the
west and diminish through the day. Winds will further back to the
southwest this evening and then remain less than 10kts.

&&

PREV DISCUSSION... (Issued 306 AM CDT Wed Sep 26 2018)

DISCUSSION...

Today and tonight...forecast confidence is high.

Surface high pressure over the Central Plains this morning will
slide by to the south later today and tonight. We are clearing out
nicely this morning, but the combo of lingering cyclonic flow
aloft and steep low level lapse rates should result in a sct-bkn
CU deck later this morning and afternoon. Those diurnally driven
clouds will clear out quickly this evening, setting the stage for
a chilly night with lows in the lower to mid 40s.

Thursday - Confidence...Medium
Southwest winds will bring a thermal ridge axis into the cwa
ahead of an advancing surface/850 cold front. the progs have been
pretty consistent in generating some light rain showers with this
feature. there are some embedded vort maxes within the broad 500
millibar flow pattern. So will carry shower chances with this
feature for most of the day. Some light rain may linger into the
evening in parts of the north and east.

Thursday night and Friday - Confidence...Low to Medium
The ECMWF is an outlier with hanging up the 850 baroclinic zone
across the cwa this period resulting in a more robust slug of
rain developing into Friday. Meanwhile the GFS/NAM and GEM are
showing the main action shifting to our south with a more
progressive fropa. However these models also show some shra
potential with in a cold advection regime with mid level cyclonic
flow. So the blended pops take this into account though not to
the extreme of the outlier ECMWF solution.

Friday night and Saturday - Confidence...Medium
Chilly airmass settling in with surface ridging. This should set
up some frost potential especially in parts of our west late
Friday night into early Saturday morning. After the cool start
the high should dominate with precip holding to our west with next
approaching system.

Saturday night and Sunday - Confidence...Medium
A warm air advection regime starts to take hold Saturday night.
Would expect enough cloud cover to advance into the area to keep a
potentially second night of frost on hold. In fact, the GFS and
GEM suggest some light rain could work in as the night wears
along. The ECMWF is looking dry through Saturday night. By Sunday
the ECMWF shows a stronger waa signal while the GFS shows less
isentropic ascent but some weak lower level convergence. So will
maintain some rain chances. The ECMWF shows the surface warm front
lifting through area while the GFS and GEM keep the boundary to
our south. So some uncertainty at this time with respect to temp
trends.

Sunday night through Tuesday - Confidence...Low
Pattern looks unsettled as a GEM/GFS timed warm front may work
through early in this period with some showers/storms also possible
with a trailing cold front as low pressure lifts northeast from
the Plains, though some synoptic/timing differences appear this
period. Have used blended pops for now.


&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Boxell
Today/Tonight and Aviation/Marine...Boxell
Thursday THROUGH Tuesday...99
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