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885
FXUS63 KAPX 240401
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1201 AM EDT Wed May 24 2017

.UPDATE...
Issued at 949 PM EDT Tue May 23 2017

Weak low pressure was in south central Wisconsin this evening,
with an ill-defined warm front extending into nrn lower, masked to
a degree by decaying lake breezes. A more developed low pressure
was in southern Illinois, which will become the dominant sfc
feature into the night, which will help winds to become east-
northeast and fairly light. The added sfc based moisture with the
warm front, slow nocturnal cooling under clouds, and winds coming
in off Lake Huron will set the stage for fog development into much
of NE lower. Fog may also form across NW lower due to wet ground
from where better rains are expected through the night. This due
to a deeper channel of moisture across this region, slightly
better low to mid level WAA, and also being closer to stronger
forcing vorticity/shortwaves rotating around an upper low in
Iowa/nrn MO. Rainfall amounts to remain more on the light side,
but slow movement of rain in weak wind environment aloft, will
allow for sustained light rain for a good period of time tonight.
Again, best rains across NW lower. Should primarily be just a
cloudy night for eastern upper. Lowest chances of seeing rain,
lightest rainfall amounts anywhere, and lowest dew points to keep
fog more at bay.

Temperatures not falling out of the middle 40s in eastern upper to
the lower 50s south of M-72.

&&

.NEAR TERM...(Tonight through Wednesday)
Issued at 335 PM EDT Tue May 23 2017

High Impact Weather Potential...Slight chance of thunderstorms thru
this evening.

Pattern Synopsis/Forecast...Elongated area of low pressure extends
from Quebec thru Michigan and Wisconsin into the Mid Mississippi
Valley this afternoon...with upper level trough aligned just behind
it to the NW. Main upper low is now centered along the Minnesota/
Iowa border...with the surface reflection taking better shape just
to the east over Southern Wisconsin under the area of max upper
level divergence. Plenty of rather weak convection continues to
develop all around this complex area of deep low pressure...with the
greatest coverage extending from Illinois into SW Lower Michigan
under that area of max upper divergence. Closer to home...scattered
showers and a few thunderstorms continue to develop along and south
of M-32 this afternoon...with the greatest thunderstorm coverage
occurring in our SE CWA further fueled and organized by enhanced low
level helicity via the opposing lake breeze.

As we head into tonight...upper low center will dive south into
Missouri as the surface low becomes reestablished over Indiana and
Ohio. Potent short wave and area of associated moisture will drive
northward ahead of the upper low into Wisconsin and Michigan...
resulting in a further northward push of POPs into the Tip of the
Mitt and Eastern Upper Michigan. Potential for thunderstorm activity
will die with sunset and should remain subsevere thru this time.
Sct/nmrs showers will continue across our CWA for the rest of the
night and into Wednesday as deep cyclonic flow and ample low level
moisture remain in place. Better synoptic support via the short wave
and the low itself will push further south toward the Ohio Valley.
We will see a slight chance of thunder tomorrow afternoon...but this
should be mainly limited to our far southern CWA along and south of
M-55.

Low temps tonight will range from the mid 40s in Eastern Upper
Michigan to the lower 50s across our SW CWA. High temps on Wednesday
will be mainly in the low to mid 60s.

&&

.SHORT TERM...(Wednesday night through Friday)
Issued at 335 PM EDT Tue May 23 2017

...Unsettled and a little cool through at least Thursday...

High Impact Weather Potential...None expected.

More of the same really as the cutoff upper level low continues to
send upper level disturbances our way from time to time.
Short/medium term models vary on the details/timing of individual
waves as well as when/if main upper trough exits off to our east. At
this point will continue with periodic shower chances through
Thursday night as per the blend but could foresee activity hanging
around through Friday as well. Highs in the upper 50s to middle 60s
Thursday and the middle 60s to lower 70s Friday. Lows in the middle
40s to around 50.

.LONG TERM...(Friday night through Tuesday)
Issued at 335 PM EDT Tue May 23 2017

Consternation continues concerning convection for the second half of
the holiday weekend. Still a lot of disparity in the guidance, with
showers moving in at all kinds of different times Sunday/Monday.
Still think the majority of any rain that occurs will be one day or
the other, rather than spread over a couple of days that current
PoPs depict. But narrowing that down to what day at this point is
the problem. As such, will run with the blend PoPs and refine
through the week. Temperatures are expected to run near to slightly
above normal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1153 PM EDT Tue May 23 2017

Weak low pressure was in SE Wisconsin, with an ill-defined frontal
boundary extending into lower Michigan, masked by very weak/near
calm wind flow. A more developed low pressure was in southern
Illinois, which will become the dominant sfc feature overnight,
which will help winds to become very light out of the east-
northeast. Minimal temp/dew point spreads, slow nocturnal cooling
under a blanket of clouds, and these very light winds coming in
off Lake Huron, will set the stage for MVFR to IFR CIGS and fog
for APN. Could see fog across the NW lower airports is the clouds
could thin a bit. Plus, better rains have fallen across this area,
and the wet ground will help in the development of fog. CIGS
remain difficult, as latest data still suggesting a period of
MVFR/IFR in NW lower as well. Not as confident in this however,
and have scaled back the length of time for these low clouds.

It may take awhile to get rid of the fog across APN Wednesday
morning. Confidence is somewhat low on how long VSBY restrictions
will last. The sfc low will only work very slowly east into
Indiana Wednesday, with additional scattered showers wrapping
around it`s nrn periphery, and into nrn Michigan for Wednesday and
Wednesday evening.

&&

.MARINE...
Issued at 335 PM EDT Tue May 23 2017

Winds and waves will remain below SCA criteria tonight thru
Wednesday night as the surface pressure gradient stays rather loose
overhead. Scattered showers will continue to impact most of our
nearshore areas thru Wednesday night as weak low pressure holds over
Michigan.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...SMD
NEAR TERM...MLR
SHORT TERM...AJS
LONG TERM...ALM
AVIATION...SMD
MARINE...MLR