Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 210358
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1158 PM EDT Thu Jul 20 2017

.UPDATE...
Issued at 940 PM EDT Thu Jul 20 2017

Clear skies across the region at the moment, with only some high
cloud looking to cross into the far SW CWA around Manistee and
Cadillac over the next few hours. Additional high cloud may arrive
overnight, from convection over the Dakotas. The quiet weather is
courtesy of high pressure moving into nrn Michigan. High dew
points in the 60s will lead to a mild night with some fog likely
in spots.

&&

.NEAR TERM...(Tonight through Friday)
Issued at 315 PM EDT Thu Jul 20 2017

...Some patchy fog tonight...warm Friday with increasing clouds...

High Impact Weather Potential...None.

Pattern Synopsis/Forecast...Quasi-stationary front extends from the
Central Plains thru Iowa and into far Southern Lower Michigan this
afternoon. High pressure continues to build into the Northern
Lakes...with no precip occurring across Minnesota...Wisconsin and
Michigan. Broken line of mainly high clouds continues to stream
eastward thru this area. Latest vsbl satellite combined with local
obs show patches of diurnal CU development within this region as
well. Temps have warmed into the 80s across most of our CWA...as
dwpts very slowly fall with the arrival of drier low level air.

As we head into the evening hours...diurnal CU will dissipate with
sunset/loss of daytime instability. Some scattered cirrus will
continue to drift overhead during the night and into Friday. Expect
some patchy fog development late tonight/early Friday morning under
mainly clear skies and light/calm winds. Any fog that does develop
will quickly mix out shortly after sunrise...giving way to another
mainly sunny and very warm day across the Northwoods.

Low temps overnight will cool into the upper 50s and lower 60s. High
temps Friday afternoon will warm well into the 80s across much of
our CWA.

&&

.SHORT TERM...(Friday night through Sunday)
Issued at 315 PM EDT Thu Jul 20 2017

.SHORT TERM...(Friday night through Sunday)

...Showers and thunderstorms possible at times...

High Impact Weather Potential...Thunderstorms possible at times
Friday night through Saturday night. Small chance of thunderstorms
again Sunday afternoon.

Pattern Synopsis/Forecast...General zonal flow pattern in the upper
levels will continue into Saturday and early Sunday before a
developing trough digs into the Upper Great Lakes region Sunday
afternoon. Until then, occasional ripples of mid level energy,
especially in the Friday night-Saturday morning timeframe, will be
the primary driver for showers and storms at times across the
region. This activity will be further enhanced by a developing
surface low initially over southern MN/northern IA and an associated
warm front as these features approach northern Michigan.

Primary Forecast concerns...Aside from usual difficulties of
forecasting timing and location of possible convection, pinpointing
the track of a potential MCS Friday night into early Saturday
remains the primary forecast concern.

Models are in good agreement with a fairly sharp moisture/theta-e
gradient setting up along the warm front Friday evening, stretching
from central MN into western WI and down through northern IL and IN.
Deeper moisture will be found on the warm side of the front where
PWATs may climb > 2 inches. Looking fairly likely that an MCS will
develop late Friday afternoon over central MN/northwest WI, then
track southeast along this moisture/instability gradient overnight.
How this activity will evolve overnight as it interacts with a
veering low level jet is less certain. While several synoptic models
have the forward-propagating MCS spreading out in a W to E fashion
as it enters southern WI, nearly all keep the bulk of the activity
downstate as it crosses into Lower Michigan...perhaps brushing the
southwestern portion of the APX CWA. SPC day 2 keeps marginal/slight
risk severe outlook downstate. There may be some concurrent weak
activity that develops over northern MI Saturday morning, as per the
latest NAM/GFS/ARW.

Less confidence as to when/where/if convective redevelopment may
occur during the day Saturday in response to more mid level
perturbations and approaching warm front. This will depend on how
much we can destabilize behind the morning MCS. If we can recover
instability-wise (complicated by ongoing WAA and resultant weak low
level lapse rates) and storms manage to develop, there may be
sufficient deep layer shear to support a few better organized storms
Saturday afternoon/evening. However, overall convective activity on
Saturday looks mostly unorganized. SPC Day 3 outlook has northern
Lower in a marginal to slight risk.

Additional chances for showers/storms will linger into Saturday
night and Sunday as weak surface low crosses Lower Michigan and
digging upper trough drops into the Upper Great Lakes. However,
forecast soundings show decent capping over the area and weak
low/mid level lapse rates, so think Sunday`s thunder potential will
be more inhibited than Saturday.

.LONG TERM...(Sunday night through Thursday)
Issued at 315 PM EDT Thu Jul 20 2017

High Impact Weather Potential: Minimal.

Large scale pattern features a typical summertime look to it with a
broad area of weak flow/high heights across much of the CONUS with
main westerlies confined to the northern tier of states.  Short wave
troughing will be making its way across the Midwest/Great Lakes this
weekend...leading to eventual troughing/height falls spreading into
the northeast and Mid Atlantic for early next week.  So no big heat
for the region for the first half of next week...though temperatures
look to moderate beyond Monday.  Start of the week looks dry in the
wake of the short wave trough passage and building short wave ridge
for Monday/Tuesday.  Next chance for rain probably by midweek in
developing warm advection pattern ahead of a cold front/short wave
trough.

Temperatures will be seasonably cool Monday (mostly 70s for
highs)...warming back to something more typical for late July by
Tuesday (70s to around 80) which should continue into midweek though
could be tempered by potential precipitation (especially
Wednesday??).

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1155 PM EDT Thu Jul 20 2017

Outside of some expected fog development tonight, conditions will
remain VFR this TAF period with weakish high pressure over the
region. W/NW AOB 10 kts will go near calm tonight with lake
breezes expected Friday afternoon. Next shot at showers and a few
possible storms rolls in late in the TAF period, attm, best
chances at MBL. Will not mention in the forecast at this time.

&&

.MARINE...
Issued at 315 PM EDT Thu Jul 20 2017

Winds and waves will remain below SCA criteria through the weekend.
High pressure will continue to build overhead tonight into Friday...
before a stationary front parked south of Michigan begins to wave
back northward Friday night and Saturday. Dry wx is expected thru
Friday...with chances of showers and thunderstorms increasing again
Friday night through Sunday.


&&

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

$$

UPDATE...SD
NEAR TERM...MR
SHORT TERM...MK
LONG TERM...JB
AVIATION...SD
MARINE...MR


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