Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 240344

Area Forecast Discussion
National Weather Service Gaylord MI
1144 PM EDT Sat Sep 23 2017

Issued at 1029 PM EDT Sat Sep 23 2017

Highly amplified flow pattern across the CONUS with impressive
592 DM 500 MB upper level high centered over lower Michigan this
evening (592 DM heights on both APX and DTX soundings flirting
with record territory 500 MB heights for this date)...and deep
troughing in the far western CONUS. Impactful weather remains
bottled up through the plains and just into the upper
Midwest...and will remain that way for the next few days.

Tonight...overall clear skies with just a few pockets of higher
level cloud cover drifting through. Another very mild and somewhat
muggy night ahead...with lows largely spanning the 60s. Very
little changes made to the going forecast.


.NEAR TERM...(Tonight through Sunday)
Issued at 324 PM EDT Sat Sep 23 2017

...More high temperature records to be challenged again on Sunday...

High impact weather potential...Minimal, although combination of
heat and humidity will definitely result in some uncomfortable
Sunday afternoon heat indices.

Pattern synopsis/forecast...Another unbelievable warm (
late September day across the Northwoods, with early afternoon
temperatures once again surging into the lower 90s across much of
northern lower Michigan (and not much cooler for those north of the
big bridge). Daily records are once again falling by the wayside,
and very likely most locations across our area will break their
daily high temperature record shortly. Add in some rather rare
northern Michigan humidity, and heat index values are reaching the
mid to even upper 90s for some areas. Hard to get these readings in
the middle of summer around these parts!

Simply not much change expected into the beginning of next week as
anamously strong and record heat producing mid and upper level ridge
remains anchored overhead. Perfect trifecta of light southerly flow,
increasingly dry soil conditions, and plentiful sunshine continues
to set the stage for high temperatures reaching or exceeding record
daily values again on Sunday.

Primary forecast concern centers on just how warm to go once again
on Sunday.

Details: As already mentioned, simply not much change to the large
scale pattern expected. Edge-of-ridge running convection remains
anchored well to our west and northwest through Sunday, and despite
such impressive warmth and humidity, capping via warm off the deck
temperature profiles expected to put a kibosh on any overhead moist
convective development (may see a few late morning and afternoon
cumulus). Much like the last several nights, likely to see a bit of
shallow ground fog develop late, but not expected to become
widespread enough for much concern. An unbelievable mild night, with
expected lows in the low/mid 60s not too far off from what normal
highs are for this time of year.

Diurnal temperature response will once again be a quick one as sun-
filled skies greet Sunday. High temperatures may fall just a degree
or two short from those experienced the last few days as off the
deck thermal profiles "cool" slightly. No matter, as daily records
will once again be in jeopardy of being broken as afternoon readings
reach the upper 80s to lower 90s. The following are current high
temperature records for Sunday :

    Record (Year)
GLR   86 (2007)
TVC   89 (2007)
APN   89 (2007)
ANJ   88 (1892)
HTL   86 (2007)
PLN 87 (2007)


.SHORT TERM...(Sunday night through Tuesday)
Issued at 324 PM EDT Sat Sep 23 2017

...More record highs likely to fall through Tuesday...

High Impact Weather Potential: Minimal

Pattern Forecast: Amplified upper level pattern across North America
this afternoon with a deep trough (-3SD) over the western U.S. and
broad ridging across the east.  Remnants of former tropical cyclone
"Jose" pushing farther away from the New England shore...while
Hurricane "Maria" moves northward away from The Bahamas.  Surface
high pressure stretches from New England southwest to the Ohio
Valley...a cold front upstream of the Great Lakes extends from low
pressure over northwest Ontario back to the central Plains.

One piece of the western trough will lift out into the northern
Plains/upper Midwest during the first part of the week...with the
southern portion of the trough left behind over the southwestern
U.S. The northern portion of this trough is expected to phase with
another short wave trough to push substantial height falls into the
Great Lakes by midweek (and ending our late summer/early fall warm
spell).  Current frontal positions to the west and north of the
state will not change substantially through the next 36 hours...but
as the upper ridge loses its influence on the region we should see a
cold frontal passage in the Tuesday time frame.

Primary Forecast Concerns: Still warm and somewhat humid to start
the week...with more widespread 80s for highs that will continue to
threaten records:

ANJ: 83(1908)
HTL: 91(1920)...likely safe
GLR: 76(1958)
TVC: 89(1908)
APN: 85(1935)
PLN: 80(2007)

An increasing precipitation threat heading into the midweek period
is the anticipated trend with approaching cold front and height
falls...question is when does this begin to impact northern
Michigan.  Front should continue to be convectively active...but
afternoon visible satellite imagery shows a lot of post-frontal
cloud cover and bands of showers/thunderstorms.  Deep-layer moisture
expected to remain prevalent across the northern Plains/upper
Midwest on the cool side of the boundary...which is not likely to
reach the forecast area until Tuesday evening.  Developing
convection across Wisconsin/western Upper may reach eastern Upper/
far northwest Lower by late in the day...and the forecast will
reflect this thinking.  Another afternoon on the warm side of the
front will bring another round of potential record breaking highs
(which would potentially be six consecutive days of record highs):

ANJ: 84(1908)
HTL: 89(1920)...maybe safe
GLR: 80(1999)
TVC: 88(1908)
APN: 88(1920)
PLN: 83(1973)

.LONG TERM...(Tuesday night through Saturday)
Issued at 324 PM EDT Sat Sep 23 2017

Big changes are a`coming as breakdown of current heat producing long
wave pattern allows a vigorous cold front to swing across the area
Tuesday night/early Wednesday. If current timing trends hold, we
will be looking at a good 10 to 15 degree temperature drop from
highs on Tuesday, with readings Wednesday struggling into the 60s
for most. Now, despite this abrupt temperature change, not entirely
sold on shower coverage as frontal attendant moisture plume becomes
increasingly narrow with time, and core of best mid level support
also becomes increasingly detached as it pinwheels northeast into
Canada. Cool temperatures will continue into the weekend, with
perhaps a reinforcing shot of colder air to arrive toward the end of
the week, with readings by Friday and Saturday perhaps running
several degrees below normal. Combination of passing mid level waves
and increasing lake processes are likely to result in a few showers
at times right into the weekend.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1144 PM EDT Sat Sep 23 2017

Solid VFR conditions anticipated tonight through Sunday night.
Light winds tonight...S/SW under 10 knots on Sunday.


Issued at 324 PM EDT Sat Sep 23 2017

Weak pressure gradient and very stable over-water thermal
profiles will keep both winds and waves below headline criteria
through early next week. Dry and unseasonably warm weather will
continue as well.




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