FXUS63 KAPX 181041

Area Forecast Discussion
National Weather Service Gaylord MI
641 AM EDT Tue Jun 18 2019

.NEAR TERM...(Today through Tonight)
Issued at 353 AM EDT Tue Jun 18 2019

Impactful weather: Scattered showers and possibly some isolated

Pattern synopsis and forecast:

upper level low pressure was centered in Quebec early this morning,
with troughing extending back westward through central Canada.
Westerly aloft was seen on the srn end of this troughing for nrn
Michigan, with a few embedded shortwaves from Wisconsin/Lake
Superior, back into SC Canada. At the sfc, features were much more
subtle, but there is a very weak area of low pressure and sfc trough
associated with the wave in WI/Lake Superior, with some minor
moisture advection (PWATs 1.00" to 1.20"). resulting in scattered
showers, and even an isolated thunderstorms over Lake Superior. This
band of higher moisture was pushing it`s way into eastern upper and
NW lower Michigan, as a band of clouds seen on latest satellite
imagery, as well as on regional MRMS radar as weak reflectivities
trying to edge into eastern upper Michigan. Maybe some sprinkles
reaching the sfc, but cloud bases are way too high for anything

The general idea synoptically today through tonight will be for the
initial wave to bring a small chance for some light rain/sprinkles
to eastern upper and portions of NW lower and far nrn lower Michigan
through daybreak. Meanwhile, the moisture advection increases over
the region this afternoon to 1.25" PWAT, ahead of a more defined
shortwave in the Dakotas/MN that reaches us this afternoon. This and
a light winds field leading to lake breezes ought to be able to
bring scattered to numerous showers for primarily eastern upper
(strongest DPVA) and NE lower (best low level lake breeze
convergence). A third and more shallow wave arrives late tonight.
The afternoon expected convection will likely wane into the evening
with loss of heating, but there is at least a chance that some lake
breeze driven showers, and the arrival of that weak low pressure and
sfc troughing resulting in a slight chance for showers through
tonight. There really is minimal MLCAPE from the GFS and RUC (100-
200j/kg) for any decent chance at thunder, but there could be some
isolated rumbles of thunder. The NAM has a likely "too wet" of BL
moisture which results in likely too much MLCAPE (several hundred
j/kg). So, will go no higher than isolated storms. Nothing severe
for sure with poor lapse rates and low shear.

High temperatures will be in the low to mid 70s most areas, with
lows tonight ranging from the upper 40s and low 50s in eastern
upper, to the mid and upper 50s for much of nrn lower.


.SHORT TERM...(Wednesday through Thursday)
Issued at 353 AM EDT Tue Jun 18 2019

Synopsis: Currently a 100kt jet exists over the Great Lakes,
situated between mild ridging over the eastern sea board, and
troughing across southern Canada. The main upper level low will
continue spinning over Quebec through Thursday; multiple subtle
shortwaves rotate around it, each providing their own chance of
enhanced shower coverage. Another shortwave currently over the
desert southwest will approach the area and pass to our south
through the Ohio Valley on Thursday, supporting a decent-
strength surface low.

High Impact Weather Potential: Minimal...shower chances Wednesday

Details/Challenges: Wednesday will see some light scattered showers
popping up over the higher terrain as diurnal heating takes hold.
Weak synoptic flow will also lend to lake breeze development in the
mid to late afternoon. Jet dynamics aloft will also help the
convection cause, and a couple hundred Joules of CAPE may make it
possible for some rumbles of thunder in the afternoon. High
temperatures will be in the low to mid 70s, with areas near the lake
shores a little cooler. The Ohio Valley low will strengthen as it
moves through the Ohio Valley. Guidance have slowed down the
progression of the low quite a bit, so that by 06z Thursday it`s
progged to be over southern Illinois. Agreement regarding strength
has gone down in the last few model runs. Either way we`ll likely
have the best chance of rain closer to Saginaw Bay.

.LONG TERM...(Thursday night through Monday)
Issued at 353 AM EDT Tue Jun 18 2019

High Impact Weather Potential: Minimal

By Friday riding starts to build into the area, and this pattern
will dominate our weather through much of the weekend. A ripple over-
topping the shortwave ridge will bring rain chances back in late
Friday night into Saturday. Better rain chances may come in on
Sunday with a surface low sweeping up through the upper Mississippi
Valley. This system drags a warm front across the area Sunday,
followed by a cold front on Monday. Temperatures head into the
weekend mainly in the lower 70s before warming a few more degrees
Sunday and Monday.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 641 AM EDT Tue Jun 18 2019

A loose pressure gradient will reside over the Great Lakes through
the TAF period, with light winds and afternoon lake breezes. There
will also be a slow arrival of weak low pressure tonight. The
combination of the low pressure, and the inland low level
convergence from the onshore flow, will result in scattered
showers with an outside shot a rumble of thunder. VFR conditions
for much of the TAF period, until MVFR/IFR stratus moves
in/develops associated with a sfc trough/cold front. Could be some
fog as well bringing down VSBYS.


Issued at 353 AM EDT Tue Jun 18 2019

A loose pressure gradient will reside over the Great Lakes through
Wednesday with no wind/wave concerns, until winds do increase some
out of the east Wednesday night into Thursday, when low pressure is
expected to cross the Ohio river valley. Attm, no advisory speeds
expected for this as well. There will be a weak area of low pressure
and sfc trough that will slowly cross nrn Michigan later today into
Wednesday, that is expected to bring scattered showers (possibly
isolated non-severe thunderstorms this afternoon).





NWS APX Office Area Forecast Discussion