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Area forecast discussion 
National Weather Service Gaylord Michigan
357 PM EDT Thursday Aug 21 2014

issued at 356 PM EDT Thursday Aug 21 2014

Mainly dry and seasonable conditions this afternoon will give way to
a gradual increase in shower and thunderstorm chances tonight into Friday.
Additional slight chances for isolated showers and thunderstorms will
continue over the weekend into early next several weak
systems track nearby.


Short term...(this evening through tonight)
issued at 356 PM EDT Thursday Aug 21 2014

..shower and storm chances (for some)...

High impact weather potential: minimal. Typical non-severe thunder
concerns tonight (lightning and locally heavy rain).

Pattern synopsis/anticipated evolution: larger scale pattern
amplification continues...with digging western troughing forcing
upper Mississippi Valley/western Great Lakes ridge amplification.
Downstream Quebec block only adding to this amplification
process...with above working in tandem to build overhead heat dome
through this weekend. Strong warm/moist advection and attendant
thermal/instability gradients kicking off areas of showers and
storms to our west and south...some of which have been rather
prolific rainfall producers. Much quieter and cooler closer to
home...with area well removed from quasi-stationary warm front
draped over the lower lakes.

Primary forecast concerns/challenges: shower/storm evolution.

Details: just another northern Michigan low confidence shower and
storm forecast. Just upstream tight moisture/instability gradient
forces such forecast unpleasantries...and that does not look to
change much during the overnight. Some slow east progression for
sure...but by and large better shower and storm chances look to
remain off to our west and south...with the latter areas enhanced by
developing and steadily veering low level jet structure. Rains will
only help tighten already well established southwest lakes thermal
gradient...which in turn will act to reinforce current lower lakes
quasi-stationary front. Simply have no reason not to believe vast
majority of high resolution model guidance /strongly supported by
simple pattern recognition/ that most of the heavier rain producing
showers and storms will propagate east/southeast into and through
the lower lakes. Key for US further north will be interaction of
subtle shortwave and subsequent uptick in off the deck warm air advection regime.
Believe this may provide the spark to kick off some rain...
especially across far southwest areas where above intercepts
northern extent of possible southwest lakes convective complex. Will
largely keep inherited forecast in-tact...tailoring probability of precipitation rapidly
from southwest to northeast...keeping eastern upper and northeast
lower mostly dry overnight. Expecting any severe/heavy rain threat
to remain outside our area.


Long term...(friday through thursday)
issued at 356 PM EDT Thursday Aug 21 2014

..warm and humid through the weekend and early next week...

Four to five wave hemispheric pattern in place to start this
forecast cycle with long wave troughiness across western noam and
ridging building across the southeast states. Short wave ridging continues
to build across the Gulf Coast states with ridging/warm air building
up through the Midwest and far western Great Lakes...setting up a
classic "ring of fire" pattern. One round of decaying convection
along/north of warm front draped through that area. Further
upstream...strong short wave energy out of the Gulf of Alaska
digging into the Pacific northwest...that will carve out substantial
troughiness across the western Continental U.S. By this weekend...leading to
building heights/warmth through the Great Lakes. But with the
building heights/moisture gradient sitting across the Great Lakes
into the Midwest...the biggest forecast challenge through the
weekend will continue to be daily precipitation chances.

Friday and Friday night...surface warm front will remain draped from the
Midwest into the Ohio Valley with the gradient of moisture/
instability from western Upper Michigan down through lower Michigan.
Will likely be another round of convection ongoing Friday morning
along that gradient although the exact location of development later
tonight remains uncertain at this point...which of course will
impact where it ends up. Right now...believe most of the active
weather will occur west and south of this County Warning Area along a line from northern
Wisconsin down through central and Southern Lower Michigan...grazing our
southern couple tier of counties Friday morning. But it/S also possible
convection takes off further south from Iowa into the Ohio Valley
pretty much missing northern Michigan altogether. Will hold on to Chancy
probability of precipitation Friday morning across the SW third of the County Warning Area. After morning cover thins out for the afternoon hours with
temperatures warming to the middle 70s to lower 80s and dewpoints in
the middle to upper 60s. Moisture pooling/instability and low level
convergence this go around looking to set up across the SW counties
where there may be a few afternoon/early evening showers or rogue
thunderstorm. Chances are not great...but enough to retain low probability of precipitation
in the forecast. Dry later Friday night with patchy fog a good bet
once again.

Weekend forecast...guidance consensus has pretty much fallen in line
with the idea of short wave troughiness deepening across the northern/
central rockies while sharp downstream ridge axis pokes up into the
Great Lakes...Saturday through Sunday. Have become increasingly
convinced that much if not all of the weekend will turn out warm but
precipitation-free at least for 95 percent of the County Warning Area...while bulk of the
weather "action" gets re-focused from the Central Plains into the
upper Midwest as one or more waves ride up through that region. But
with warm and relatively humid conditions across the state...could
there be a few pop-up showers either day...yes. But just not feeling
good about having such a wet looking forecast when I/M reasonably
convinced that most locations remain dry. So...have reduced probability of precipitation to
just slight chance (20) for both Saturday and Sunday which does not
show up in the zone forecast product beyond day 2. Temperatures...upper 70s
to middle 80s both days but higher dewpoints in the 60s will make
things feel a bit uncomfortable.

Monday through Thursday...short wave trough in The Rockies looking
to dislodge and advance into the upper Midwest/Great Lakes
midweek...pushing a cold front through the region and knocking
temperatures back down to at or below normal readings.
upper ridging across the Great Lakes slips east of the state for
Monday and Tuesday and will open the door just a little bit more to
precipitation chances for both Monday and Tuesday. Greater precipitation chances
come late Tuesday through Wednesday with frontal passage before things dry out
and cool off by Thursday.

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 141 PM EDT Thursday Aug 21 2014

..low confidence forecast...Especially tonight...

Morning stratus deck continues to steadily mix out...leaving
behind a VFR/MVFR stcu deck this afternoon. Challenging forecast
tonight as upstream convection attempts to make a run at the
western taf sites. Definitely not sold on such...with better
instability remaining off to our west. Best potential for showers
down near Manistee...although heavier rains should pass by to
their south. Otherwise...lingering boundary layer moisture
supports renewed low cloud development tonight...once again
leading to MVFR/IFR conditions. More rains than currently
anticipated would lead to possible fog development. Conditions
slowly improve Friday morning as mixing increases.

Light winds throughout this taf cycle.


issued at 356 PM EDT Thursday Aug 21 2014

Marine...light east wind regime to continue into this weekend. Main
focus for showers and storms expected to stay off to our south and
west for the next several days...with the best chance for any
showers and storms across the northern lakes tonight into Friday
morning...although no significant wind gusts or rains are expected.
Will need to watch fog potential heading into this weekend as warm
and increasingly moist air overspreads the still Cool Lake


Apx watches/warnings/advisories...


short term...msb
long term...Adam

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