National Weather Service - Area Forecast Discussion

000
FXUS63 KAPX 230615
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
215 AM EDT Mon Jul 23 2018

.NEAR TERM...(Today through Tonight)
Issued at 213 AM EDT Mon Jul 23 2018

...Still a bit damp for some...

High impact weather potential: Minimal.

Pattern synopsis/forecast: Pesky upper level troughing remains,
locked in place by a well northward displaced progressive northern
stream flow regime. Light showers and areas of drizzle continue as
weak support interacts with still plenty of lingering deep layer
moisture. Precipitation amounts overnight have been light, mostly
well under a tenth of an inch.

Really, not a whole lot of change heading through the next 24 hours
or so as both troughing and attendant moisture plume remain
overhead. Forcing is never great, but minor diurnal contribution and
maintenance of that trough axis supports some additional mostly
light shower activity right through tonight.

Primary forecast concerns/challenges: Addressing that additional
shower potential, along with temperature and cloud trends.

Details: Nothing really to hang your hat on with regards to specific
forcing to drive additional shower development today and tonight.
There is some hints of enhanced low level convergence across
northwest lower and eastern upper Michigan, with diurnal trends
supporting the development of perhaps a bit of instability within
this convergence axis very late this afternoon and evening. Some
drying noted this morning within the mid and upper levels, with the
return of a bit better moisture this afternoon and evening to
perhaps entice shower development. Confidence is most definitely low
with regards to both spatial and temporal detail to any shower
activity right through tonight. Will focus "best" shower chances
along that anticipated convergence zone, but even there will keep
low end chance pops at best. Not expecting any thunder as updrafts
appear weak enough in the mixed phase portion of the clouds to
prevent good charge separation. Definitely more clouds than sun
today, with perhaps a few more breaks developing in the overcast
tonight. Those clouds and light east to northeast flow will keep
temperature just a bit below normal today, with readings topping out
mostly in the middle 70s this afternoon. Lows tonight ranging from
the upper 50s to middle 60s.

&&

.SHORT TERM...(Tuesday through Wednesday)
Issued at 213 AM EDT Mon Jul 23 2018

....Occasional shower chances continue..

High Impact Weather Potential: Slight chance of thunderstorms
Tuesday afternoon, primarily across northern lower.

Pattern Forecast: Ridging across the western Atlantic allowing very
little eastward progress of this weekend`s well-advertised unsettled
weather. Closed upper level circulation centered across the
Ohio/Tennessee Valleys early this morning will gradually become an
open wave through Tuesday, but make very little eastward movement
while doing so. Meanwhile, a strengthening system across Manitoba is
expected to be evident early this week with a shortwave ejecting
toward the Great Lakes during the day Tuesday. An attendant cold
front, combined with lingering moisture across the region from this
weekend`s system, may be enough to spark a few showers and/or
thunderstorms across a portion of northern Michigan...primarily
Tuesday afternoon. A weak area of high pressure is then expected to
follow for the midweek time frame before another system gets set to
approach the region late Wednesday night into Thursday.

Primary Forecast Concerns/Challenges: Shower/storm chances Tuesday.

A sharp gradient with respect to deep layer moisture is progged to
be in place across northern Michigan come the start of the period
Tuesday morning with PWs progged at greater than 1.50 inches east of
I-75...tapering quickly to less than inch near the Lake MI shore
line. A combination of afternoon lake breezes and a weak surface
boundary progressing west to east throughout the day is expected to
be enough to kick off scattered showers and a few thunderstorms...
mainly focused east of I-75 across northeast lower and eastern
upper. Early day peeks of sun are expected to promote diurnal
destabilization with MLCAPE values pushing 1,000 J/kg by mid-
afternoon. With little in the way of bulk shear (AOB 20 kts), severe
weather isn`t a glaring concern, but any thunderstorms could produce
locally heavy downpours.

Much drier air is eventually expected to arrive Tuesday night into
Wednesday as high pressure gradually sags into the region from the
west. Thus, quieter conditions are expected on Wednesday with
light winds, mild temperatures, and mostly sunny skies.

High temperatures Tuesday ranging from near 80 to the mid 80s area-
wide. Wednesday`s highs climb a couple of degrees...from the low to
upper 80s across northern Michigan. Each day will likely see lake
breezes develop keeping the immediate shorelines several degrees
cooler.

&&

.LONG TERM...(Wednesday night through Sunday)
Issued at 213 AM EDT Mon Jul 23 2018

High Impact Weather Potential: Minimal.

Primary focus through the extended forecast period revolves around
the Wednesday night through Friday timeframe as a well-defined wave
and associated strengthening surface low are expected to trek from
southern Manitoba into southern Quebec by the end of the week. This
system will have the potential to bring occasionally unsettled
weather to northern Michigan with the highest chances for
precipitation arriving late Wednesday night - Thursday in
association with the system`s cold front crossing the forecast area.
However, pockets of wrap around moisture lingering into the end of
the week may continue on/off shower chances through at least a
portion of the upcoming weekend (with even some lake induced rain
showers on Friday?).

A cooling trend will be evident through at least the first half of
the extended with the coolest day on Friday as current trends
suggest high temperatures struggling to reach much past the low-mid
70s for most.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1155 PM EDT Sun Jul 22 2018

IFR cigs overnight APN, then improving to VFR.

Slow-moving low pressure is along the WV/KY border, which a
secondary and weaker low over southern Lk Huron. Showers/
drizzle/low clouds continue to be thrown back into ne lower MI,
and at least a few of those showers will linger into much of
Monday. IFR cigs will prevail at APN, with some periods of MVFR
conditions possible at the other TAF sites, especially PLN. Cigs
will improve during the day on Monday. However, may to watch for
stratus/fog redevelopment Monday night.

Northerly breezes up to 12kt.

&&

.MARINE...
Issued at 213 AM EDT Mon Jul 23 2018

Weak low pressure, responsible for some gusty northeast
winds on Lake Huron this past evening, will continue to weaken as it
rotates further southwest into south central Michigan this morning.
Attendant increasingly diffuse pressure gradient will result in a
gradual decrease in wind speeds today. Pressure gradient then
remains weak for the next several days, resulting in both winds and
waves remaining below advisory criteria through at least the middle
of this week.

&&

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

$$

NEAR TERM...MB
SHORT TERM...MG
LONG TERM...MG
AVIATION...JZ
MARINE...MB

NWS APX Office Area Forecast Discussion