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Area forecast discussion 
National Weather Service Marquette Michigan
129 am EDT Friday Jul 25 2014

Short term...(this evening through friday)
issued at 342 PM EDT Thursday Jul 24 2014

Smoke from fires over northwest Canada has lingered across the
eastern half of the County Warning Area...and kept skies across eastern/parts of
central Upper Michigan hazy looking. Lingering moisture out east with the
exiting trough led to some brief patchy fog out east this morning on
Lake Superior...but otherwise...forecast for this afternoon stayed
on track with high pressure in place.

Aloft...the strong ridge extending from New Mexico into Manitoba
today will begin to break down as low pressure crosses the Canadian
prairies. Low pressure is also situated over northern Quebec. This
will lead to a more zonal flow over Upper Michigan for Friday.
Meanwhile...at the surface...high pressure centered over lower Michigan
and the Ohio Valley this afternoon will sink southeastward into the
Middle Atlantic States overnight. The surface low occluding over
Alberta will force an occluded front into Minnesota by Friday
evening...and another low that develops along this front will sweep
into Iowa...with a warm front draped across Illinois. With return
flow from the high to the southeast and the approaching low pressure
systems...Upper Michigan will see a healthy moisture transport starting
late tonight and continuing through Friday. Precipitable waters generally reach up
to around 150 percent of normal by the afternoon hours. This will
bring in cloud cover for Friday...spreading west to east through the
day. As far as precipitation GOES...the best upper level
support...courtesy of a shortwave swinging around the base of the
low in Quebec and weak isentropic ascent...will not arrive until the
afternoon hours. Have kept chance-slight chance probability of precipitation accordingly.

Temperatures will be warmer tomorrow despite incoming cloud
cover...with 850mb temperatures around 12-14c. This puts Upper Michigan squarely
in the 70s...and closer to 80 inland from the lakes in areas that
see more sun.

Long term...(friday night through thursday)
issued at 342 PM EDT Thursday Jul 24 2014

This weekend will bring unsettled weather a as deep closed low now over the
Pacific northwest moves across scentral Canada on Friday/Sat and then through the upper
lakes on sun under the influence of west-northwest flow aloft between deep closed low
over northern Quebec and mean ridge over The Rockies. Much cooler air will
invade the area late this weekend into at least the middle of next
week as the digging shortwave amplifies the Quebec trough into all of eastern
namerica.

Friday night/Sat...closed low now over the Pacific northwest is forecast to move slowly
through southern Saskatchewan to near Lake Winnipeg. Although this disturance
and associated strong deep layer forcing are forecast to be remain well
upstream...a good number of the numerical models show a weaker
shortwave/axis of DPVA and relatively weak deep layer qvector cnvgc well
in advance of the main disturbance moving east-southeastward through the upper lakes
late Friday night/Sat morning. While there may be some lingering showers on
Friday evening associated with the return of moister air/precipitable water near 1.5
inch in the low level SW flow between lower mslp in the plains and hi pressure
off the middle Atlantic coast...shower/ts chances should increase again
later Friday night/Sat morning as incoming shortwave/band of forcing arrive.
But many of the models show this forcing coinciding with some drying
aloft... with overall quantitative precipitation forecast rather limited. Will retain flavor of going
forecast that shows lingering chance probability of precipitation. The arrival of dnva/deep layer
qvector dvgc and more drying aloft in the wake of this shortwave/ahead of
trailing shortwave ridge will diminish lingering probability of precipitation west-east on Sat afternoon. But
daytime heating associated with the drying on Sat afternoon may result in
additional diurnal showers/ts...mainly over the east closer to
departing moisture and where lake breeze cnvgc could increases the chance for
convection. Temperatures on Sat away from lake moderation are likely to rise at
least close to 80 with some afternoon sunshine and 850 mb temperatures as hi as
16-17c over the west at 00z sun.

Sat night through Sun night...expect incrsg chance of showers/some ts west-east
later Sat night as closed low shifting east-southeastward toward Western Lake supply and
accompanying sharp deep layer qvector cnvgc aprch Upper Michigan. The most
widespread showers will occur on Sun morning as upper low tracks across northern WI...
placing Upper Michigan on the favored cyclonic side of the path of this feature
and under sharp DPVA/upper dvgc/deep layer qvector cnvgc. These probability of precipitation will
diminish northwest-southeast Sun afternoon/evening with arrival dnva/drying/deep layer
qvector dvgc in the wake of shortwave departing to the southeast through lower Michigan.
With a north flow developing over the area off the chilly lake waters on sun as
accompanying surface low tracks into lower Michigan ahead of the shortwave...temperatures
over the ncentral with upslope flow off the lake are likely to remain
steady or fall through the 50s in the presence of more persistent low
clouds. 850 mb temperatures dipping to 4-6c by 12z Monday will allow min temperatures to
fall into the 40s at many places on Sun night.

Monday through Thursday...the upper lakes will be under a north-northwest flow aloft between the
unseasonably deep upper trough over eastern namerica around closed low in
Quebec and persistent mean ridge over the west...resulting in well below
normal temperatures early in the week with 850 mb temperatures as low as 4-6c on Monday
morning and low level north winds advect lake supply cooled air onshore. Although 850 mb
temperatures are forecast to moderate to around 12c by middle week...overall temperatures
should remain below normal. Another concern on each of the days will be
the potential of some mainly diurnal instability showers under
larger scale cyclonic north-northwest flow. Looks like the best chance for these showers
will be on Tuesday and Wednesday as several of the longer term models show the
closed low in Quebec drifting closer to Upper Michigan as a stronger shortwave
digs southward through Ontario around the cutoff and slowly moderating surface-850 mb
temperatures result in more instability.
&&

Aviation...(for the 06z tafs through 06z Friday night)
issued at 129 am EDT Friday Jul 25 2014

VFR conditions are expected at all sites through the forecast
period. Expect that any light rain showers that develop late in the
afternoon into the evening and put prob30 into all sites then.
&&

Marine...(for the 4 PM Lake Superior forecast issuance)
issued at 342 PM EDT Thursday Jul 24 2014

Expect winds under 15 kts through Sat night with relatively weak pressure
gradient dominating the upper lakes. Stronger north winds up to 20-25
kts are possible on sun into Monday as cooler air invades the area
under tighter gradient between hi pressure moving into the northern
plains and low pressure over the southeast Great Lakes. Winds will diminish on
Tuesday and back toward the west with closer approach of hi pressure from the
plains.
&&

MQT watches/warnings/advisories...
Upper Michigan...
none.
Lake Superior...
none.
Lake Michigan...
none.
&&

$$

Short term...mesoscale discussion
long term...kc
aviation...07
marine...kc

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