Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 261703
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
103 PM EDT FRI AUG 26 2016

.UPDATE...
Issued at 1015 AM EDT Fri Aug 26 2016

High pressure remains over the Great Lakes region late this
morning. Tail end of a secondary cold front has entered Western
Lake Superior...producing a band of scattered showers and low
clouds over Western Upper Michigan ahead of the boundary. Skies
remain mostly clear across our CWA attm...but latest vsby
satellite and a look out our office window shows some diurnal CU
beginning to develop thanks to colder air aloft advecting into the
region behind the initial cold front that moved thru yesterday.

As we head into the afternoon...the secondary cold front will clip
our northern CWA...as will the associated scattered showers and
area of low clouds along and ahead of the boundary. Diurnal CU
will continue to develop...with the greatest coverage across
interior sections of Eastern Upper and NE Lower Michigan where
weak lake breeze development will lend additional low level
convergence and support for CU development.

Current forecast reflects this scenario fairly well. No major
adjustments needed attm. Today will be less humid and not quite as
warm as the past few days. Afternoon highs will range from the
lower 70s in Eastern Upper and far NW Lower Michigan to around 80
degrees across much of NE Lower Michigan.

&&

.SHORT TERM...(Today and tonight)
Issued at 354 AM EDT Fri Aug 26 2016

...Isolated pop-up showers possible today...

High impact weather potential: None.

Overview: Bigger picture view features upper level ridging/high
pressure across the SE CONUS and through the Gulf of Alaska, with
larger scale troughiness dipping through the western CONUS and
northern plains. Broad belt of stronger flow aloft and upper jet
core runs from the upper midwest, across the northern Great lakes
and into southern Quebec. Better defined short wave is exiting
eastern Ontario into Quebec. Smaller, subtle short wave is pushing
eastward through central Minnesota.

Today: Subtle short wave trough looking to run across the northern
lakes region today on the heels of the upper jet core advancing
into Quebec. Model guidance suggest very minimal QG-forcing for
ascent with this feature. However, slightly cooler temps aloft
sliding through the northern lakes may result is some very modest
low level instability across upper Michigan this afternoon (on
the order of a few hundred J/KG). And with lighter wind fields and
development the typical inland convergence across upper Michigan,
think a few afternoon showers are possible up that way. Nothing
across northern lower Michigan with warmer temps aloft/capping.

Tonight: Should be fairly quiet overall. Upstream troughiness will
be advancing into the northern plains/upper midwest region
overnight, along with the development of stronger low-mid level
flow and moisture/instability transport into the midwest/far
western Great Lakes. Still appears that any and all precip
activity will remain to our S/W until later Saturday. But, I do
expect a thicker band of low-mid cloud cover to advance up into
our area during the overnight hours. Might be more concerned about
an elevated shower threat spreading into our area overnight, but
there just is not any elevated instability to work off of.

.LONG TERM...(Saturday through Thursday)
Issued at 354 AM EDT Fri Aug 26 2016

High Impact Weather: Thunderstorms Saturday

(8/27)Saturday...Main concern will be the initial line of convection
Saturday morning as the 500 mb speed max is moving into northern
Michigan along the warm front. 0-6 km shear is around 40knots
through the day although, the instability doesn`t look that great
with fairly skinny CAPE and only a couple of hundred J/kg. Will have
to watch this for potential, but for now, general thunderstorms
would be expected. As we get into the evening, the 500 mb shortwave
trough begins to push through and the 700-500 mb layer rh falls to
less than 20% and the baroclinic zone should be far enough north to
just have rain showers, and some small chances for thunder.

(8/28)Sunday...Should be a clear day as the sfc high builds into the
region. The GFS begins to produce rain late Sunday afternoon and
into the evening, especially in E Upper as a second 500 mb trough
moves into the region. The ECMWF ridges at 500 mb through the night,
lifting any precipitation makers north of the region. Considering
the GFS and ECMWF 500 mb flows and the sfc pattern look relatively
the same, wonder if the GFS sfc moisture issues is kicking off
showers and thunder when there isn`t any. So will keep the night dry
as well.

Extended (Monday through Thursday)...As was advertised yesterday
that there would be a pattern change, the extended is beginning to
take shape with that thought. Monday, the zonal flow at 500 mb
begins to break down with a 500 mb ridge beginning to build in the
Rockies and the trough over the eastern states. Monday/Tuesday,
the GFS is wet over the Upper Great Lakes, while the ECMWF dry
Monday with a front passing through Tuesday, then a more amplified
Ridge/Trough pattern sets up by Wednesday morning and looks to
keep the region dry through Thursday, although the ECMWF is trying
to break off some energy and ride it into the Upper Great Lakes,
along a back door cold front pushes in from the northeast. Maybe?
confidence on the wet or dry solution at this point is low. Think
that maybe, the GFS has the better idea, but will go with low
chance pops in the extended.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 103 PM EDT Fri Aug 26 2016

Overall conditions will remain VFR thru the 24 TAF forecast
period. High pressure centered overhead thru tonight will give
way to increasing chances of showers and thunderstorms on Saturday
as low pressure lifts NE into the Western Great Lakes region.
Chances of thunder are rather small thru 18z Saturday...so will
leave this out of the TAF for now. Will include VCSH for MBL and
TVC beginning at 14z...with chances of precip likely holding off
until after 18z for PLN and APN. West winds at around 10 kts this
afternoon will become light/variable tonight and then shift to the
SE below 10 kts on Saturday ahead of the approaching low pressure
system.

&&

.MARINE...
Issued at 354 AM EDT Fri Aug 26 2016

Surface high pressure will build across the western Great Lakes
today through tonight. Steady westerly winds anticipated on the
lakes through much of the day, weakening tonight. But all
winds/waves are expected to remain below any marine headline
criteria.

Saturday, winds turn back into the S-SE as the high pressure
system departs off to the northeast. Slightly stronger winds again
for Saturday, but again below any marine headline criteria.

&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...MLR
SHORT TERM...Adam
LONG TERM...JSL
AVIATION...MLR
MARINE...Adam


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