000
FXUS63 KAPX 211709
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
109 PM EDT Sun May 21 2017

.UPDATE...
Issued at 1004 AM EDT Sun May 21 2017

Low pressure continues to slowly lift N/NE thru the Upper
Mississippi Valley late this morning. Associated cold front
curves from the low center now located along the
Minnesota/Wisconsin border...bisects Wisconsin and then turns
south thru Southern Lake Michigan into Indiana. Relatively weak
convection continues to fire along and ahead of the low center
and the cold front...part of which is impacting our CWA from
around TVC to HTL. Scattered showers and isold thunderstorms will
continue to lift northward thru our CWA as we head into the
afternoon hours. The SW half of our CWA will see a return to dry
weather during the afternoon as this convection lifts out of that
area...with afternoon POPs mainly confined to the NE half of our
CWA. Enough warm air should surge northward ahead of this cold
front to combine with some breaks in the cloud cover for temps to
warm into the 60s this afternoon for much of Northern Lower
Michigan. Eastern Upper Michigan will only see afternoon highs in
the mid to upper 50s.

&&

.NEAR TERM...(Today through Tonight)
Issued at 327 AM EDT Sun May 21 2017

...Threat for showers continues...

High impact weather potential...slight chance of thunder this
morning ne lower MI.

1007mb occluded low is in southern MN, with a triple point near
the WI/IL border, and a warm front just sneaking into far
southern lower MI. Surface low will move slowly nne, crossing
central Superior this evening. Initial band of rain has lifted
into upper MI while thinning out. Areas of convection are
occurring south of there, one of them lifting across eastern
lower MI. Some showers also mark the cold/occluded front in
western WI/central IL/far se MO. Precip trends as this system
lifts ne-ward are the primary challenge.

Today...the occluded front will swing across the forecast area from
sw to ne today, pushing into nw lower MI at midday, and perhaps not
quite exiting the St Marys Valley by 00z/8pm. Dry slot aloft will
eventually slightly overtake the surface front, which will help
diminish precip somewhat faster than the fropa would suggest. Se
sections are likely to briefly enter the warm sector, with dew
points creeping up toward 60f this afternoon. Warmer temps
aloft/weak lapse rates will limit instability, but some potential
for MlCapes to push 500j/kg in se sections. That will support a
chance for showers (and perhaps a t-storm or two in ne lower MI)
until the dry slot cuts things off. Ongoing radar trends clearly
support the highest pops in the morning, especially early in ne
lower MI, with pops decreasing from sw to ne from midday thru the
afternoon.

Max temps 50s in eastern upper, mainly 60s northern lower (some
coastal locales cooler, far se may take a run at 70f).

Tonight...surface and 500mb lows will gradually meander north of
Superior. Westerly low-level will be firmly established behind the
departing occluded front. Dry slot will largely be in control
this evening, but wraparound moisture pushes back into nw
lower/eastern upper MI as the night proceeds. Deep cyclonically
curved flow will contribute to precip regeneration. Sct pops
return to the forecast in those areas, primarily after 06z/2am. Ne
lower will stay largely precip- free, and in fact will enjoy
partly cloudy skies (mainly cloudy elsewhere).

Min temps mainly in the mid 40s.

&&

.SHORT TERM...(Monday through Tuesday)
Issued at 327 AM EDT Sun May 21 2017

...Showery and cool...

High impact weather potential: None.

Pattern forecast: Vertically stacked low pressure that`s plaguing
the Great Lakes region early this morning is expected to shift north
and east from southern Minnesota to near International Falls by
Monday morning. Despite a lack of deep layer moisture by Monday,
several additional weak shortwaves are expected to rotate through
troughing centered across the midsection of the country, which when
combined with diurnally driven instability is expected to provide
additional showery weather across northern Michigan to start the
week. A more potent lobe of energy is expected to drop from
Saskatchewan into the Plains before ejecting northeastward during
the day Tuesday, once again brining additional rain chances.

Primary forecast challenges/concerns: Light shower concerns and
corresponding PoPs Monday along with additional rain chances Tuesday.

By Monday morning, Sunday afternoon`s cold front will be well off to
the east with broad west-southwesterly flow expected across northern
Michigan. Several subtle waves are expected to be spinning around
the closed mid-level circulation aloft (centered to our northwest),
each increasing shower chances as they traverse overhead. Highest
PoPs will certainly be dependent on the timing of each of those
individual waves, which remains highly uncertain at this juncture.
However, best additional light shower chances look to be north of M-
72 (even more so near and north of the Staits), but the day as a
whole is expected to be far from a washout. The combination of
mostly cloudy skies, occasional showers, temperatures some 10
degrees below normal, and wind gusts 20+ mph will certainly leave
the impression of a rather cool/damp start to the work week.

Focus transitions to a more impressive wave dropping southward from
Canada into the Plains by Tuesday morning. Energy becomes stretched
out as it pushes northeastward toward the Great Lakes throughout the
day Tuesday, but is expected to provide additional rain chances
locally as an associated frontal boundary drapes across the region.
With several guidance inconsistencies with respect to timing/
strength of that wave and it`s attendant surface reflection, will
use a blend of the ECMWF/GFS/GEM for Tuesday`s PoPs, which suggests
increasing rain chances from south to north mid-late Tuesday morning
through the afternoon...highest east of I-75.

As was alluded to earlier, below normal temps are expected Monday
before rebounding several degrees Tuesday...ranging from near 60
degrees north to the middle-upper 60s near Saginaw Bay.

.LONG TERM...(Tuesday night through Saturday)
Issued at 327 AM EDT Sun May 21 2017

High impact weather potential: Minimal.

A chance of lingering rain showers continues into Tuesday night;
otherwise, the remainder of the extended looks rather quiet. High
pressure is expected to dominate from Wednesday through at least the
first half of Memorial Day weekend with temperatures climbing
several degrees each day...likely making it into the low 70s for
many for Friday into Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 109 PM EDT Sun May 21 2017

Scattered showers will continue to impact NE Lower Michigan (APN) this
afternoon before coming to a temporary end this afternoon as the
dry slot arrives in the wake of the cold front. Additional low
clouds and scattered rain showers will develop tonight into Monday
thanks to the combined efforts of ample wrap-around moisture on
the backside of the low center...increasing over-lake instability
resulting from low level CAA and deep cyclonic flow lingering
behind the low. Remaining IFR conditions will improve to MVFR/low
VFR this afternoon and tonight with the arrival of the dry
slot...but will drop back down to solid MVFR on Monday as the
wrap-around moisture and precip arrives. Surface winds will veer
from SE to S to SW as the low center tracks over Lake Superior
over the next 24 hours.

&&

.MARINE...
Issued at 327 AM EDT Sun May 21 2017

Low pressure will swing an occluded front across northern MI late
today. Gusty east to se winds will continue ahead of this front,
eventually sw to w (gusty in spots) behind it. Periods of
advisory-level conditions will continue, lasting longest on Lake
MI.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LHZ346>348.
     SMALL CRAFT ADVISORY until 5 AM EDT Monday for LHZ345.
LM...SMALL CRAFT ADVISORY until 5 AM EDT Monday for LMZ323-341-342-
     344>346.
LS...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LSZ321-322.
&&

$$

UPDATE...MLR
NEAR TERM...JZ
SHORT TERM...MJG
LONG TERM...MJG
AVIATION...MLR
MARINE...JZ