Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 201045
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
645 AM EDT TUE SEP 20 2016

.SHORT TERM...(Today and tonight)
Issued at 251 AM EDT Tue Sep 20 2016

Cold front has pushed southeast of our CWA early this morning...
leaving mainly clear skies and increasingly drier air in its wake.
Surface dwpts have fallen into the 50s across much of our CWA...
while upstream dwpts over Northern Wisconsin have fallen into the
40s.

Ridge axis over the Upper Mississippi Valley is slowly building
eastward into the Western Great Lakes region and will continue to do
so today and tonight. Skies will remain clear thru today...with some
increase in scattered high clouds tonight well in advance of a warm
front lifting northward into the Western Great Lakes region. Still
appears that the development of any precip associated with this
front will hold off across our area until Wednesday.

High temps this afternoon will range from the mid 70s across Eastern
Upper Michigan and the tip of the mitt to around 80 degrees near
Saginaw Bay. Low temps tonight will cool back into the mid to upper
50s across our entire CWA.

.LONG TERM...(Wednesday through Monday)
Issued at 251 AM EDT Tue Sep 20 2016

Wednesday through Thursday night...

High impact weather potential: Embedded thunderstorms and
locally heavy rain possible Wednesday through Thursday night.

Pattern synopsis/Expected evolution: A strong 140 kt westerly jet
streak is laid out across the northern tier of the CONUS into
southern Canada tonight, extending generally from eastern Upper MI
west-northwestward through the Pac NW. The main focus will revolve
around two separate pieces of energy, both of which are evident on
tonight`s water vapor imagery. The first, hugging the border along
Washington/British Columbia while the second, more subtle, feature
is slowly taking shape in the desert southwest/four-corners region.
The second wave, combined with positively tilting mid-upper levels
aiding to eject the energy toward the Great Lakes, will result in
low pressure development across the central plains, bringing
increased precip chances across the MS Valley and Great Lakes region
during the midweek timeframe.

Guidance continues to suggest a rather impressive baroclinic zone
setting up across the northern Great Lakes into southern Ontario by
Wednesday night into Thursday as the aforementioned low pressure
slides toward the northeast, draping a warm front across the region.
Concern lies along this nearly stationary frontal boundary in the
form of training/heavy rain potential, discussed more below.

Wednesday: As low pressure ramps up across the central plains, a
warm front is progged to extend from SD into southern MN-WI by Wed.
morning. Increasing convection across WI is expected to provide a
slow increase in cloud cover from west to east by the early morning
hours, becoming mostly cloudy by midday. As the front slowly glides
north and east, moisture will increase across northern Michigan
throughout the day with precip chances ever-so-slowly increasing
from west to east. At this point, feel we would be hard pressed to
see any scattered shower activity much further east than I-75 by
sunset Wednesday evening.

Wednesday night - Thursday night: Return flow south of the
aforementioned warm front really begins to ramp up deep layer
moisture across the area. PWs are progged to rise to 1.75+ inches by
12z Thu. If that were to verify, it would be 1.00 inch higher than
the daily mean and ~0.50 inch greater than the highest recorded PW
for Sept. 22 via SPC`s sounding climatology for APX. Thus arises the
concern for heavy rain and an inherent flooding risk from training
echoes as a nearly stationary boundary sits atop a portion of the
CWA. With that being said, it`s hard to imagine verifying the amount
of rain with this system that it would take for the region to
experience flooding concerns and with several guidance members on
both the 19/12z and 20/00z runs suggesting a much slower/weaker
system and baroclinic zone during the Wed night-Thu timeframe.
Several aspects feel eerily similar to a system last week hinting
at a widespread 2-3+ inches of rain, only to verify much less than
that. Ultimately, will continue to boost PoPs from M-32 northward
through Mackinaw County Wed night through Thu, but will forego any
mention of flooding concerns in the suite of hazardous weather
products until the mesoscale details become more clear. Something to
certainly keep an eye on over the next 36-48 hours.

Friday through Monday...

Isentropically driven precip along Wed night`s-Thursday`s nearly
stationary boundary continues through at least the first half of the
day Friday before an expansive area of high pressure ushers in
cooler/drier air from Canada Friday evening through the majority of
the upcoming weekend. Aside from a few scattered showers across far
southern zones, Friday night through the first half of Sunday are
expected to feature highs in the 60s, generally light winds and
partly sunny skies. However, an area of low pressure developing over
the northern Plains Saturday will be the next system to approach the
local area, bringing additional precipitation chances for the very
tail end of the weekend into the start of next week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 645 AM EDT Tue Sep 20 2016

Aside from some patchy fog early this morning...especially around
MBL and interior sections of Northern Lower Michigan...overall
conditions will remain VFR thru Wednesday morning as high pressure
continues to build into the Great Lakes region in the wake of a
cold front. W/NW winds will increase to around 10 kts this morning
with some gusts to 15 to 20 kts by afternoon.

&&

.MARINE...
Issued at 251 AM EDT Tue Sep 20 2016

Winds and waves will continue to reach SCA criteria across our
nearshore areas of far Northern Lakes Michigan and Huron as well as
in Whitefish Bay and the Saint Marys River System thru today. No
precip is expected today or tonight...but chances of showers and
storms will increase from west to east Wednesday and Wednesday night
as a warm front lifts into the Western Great Lakes region.

&&

.APX Watches/Warnings/Advisories...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 5 PM EDT this afternoon for
     LHZ345>347.

LM...SMALL CRAFT ADVISORY until 5 PM EDT this afternoon for LMZ341-
     342.

LS...SMALL CRAFT ADVISORY until 5 PM EDT this afternoon for LSZ321-
     322.

&&

$$

SHORT TERM...MLR
LONG TERM...Gillen
AVIATION...MLR
MARINE...MLR



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