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Area forecast discussion 
National Weather Service Gaylord Michigan
604 am EDT Thursday may 28 2015

Near term...(today through tonight)
issued at 143 am EDT Thursday may 28 2015

..lake breezes and a couple of showers/storms...

Synoptic pattern and observations:

Early this morning...not much has changed from the expectations from
24 hours ago. An ill-defined surface trough and steep lapse rates axis
aloft has slipped into the region. The trough is ill-defined due to
earlier lake breezes from central upper and NE Wisconsin...and light
winds from advancing high pressure. Scattered showers and storms had
fired off in these areas...and the mean storm layer flow was
directing them toward northwest lower...generally Leelanau County and areas
south. There was an identifiable very weak vorticity maximum that may have
been helping sustain these storms...but this was getting washed out
due to increasing height rises. Plus...waning diurnal instability
and storms moving into less unstable environment have proved
efficient at allowing this area of precipitation to dwindle and
weaken over the last several hours. Skies were gradually becoming
clearer...and temperatures were dropping into/through the 50s.

Synoptic pattern evolution and associated weather:

Feel as if the scattered showers/storms will be long gone and eroded
by daybreak....and the day starts off relatively clear. The surface high
pressure will be directly overhead this morning...before gradually
shifting east later today into tonight. Gradient winds will become
light out of the southeast heading through the day with peak
afternoon heating brining lake breezes with the maximized wind
convergence against the eastern higher terrain...extending westward
back over to roughly US 131...or slightly further west. Daytime
temperatures rising well into the 70s in northern lower with surface dew points
mixing out to 53f-55f results in 1000-1200 j/kg. Isolated-scattered
showers and storms will fire off in the low level lake breeze
convergence...and then congeal more so into the higher terrain...but
individual storm outflows are likely to keep a fairly large area of
inland northern lower under the gun for additional showers through
evening. Locally heavy rainfall is definitely
effective wind shear in the 0-10km layer is roughly 10kts...thus
slow moving cells are expected...drifting NE. Some of these NE
moving storms are likely to penetrate far Northern Lake Huron and
possibly even Drummond Island later this evening. Nowhere else in
eastern upper is expected to see there the southeast wind is
rather unfavorable...and temperatures will only reach the low 70s which
will limit the instability. Coverage of showers will wane after
nightfall. Skies will then clear through the overnight hours as forecast
soundings do show pretty deep drying.

Severe storms not expected...but will certainly need to have a
watchful eye on stronger cells. Locally heavy rainfall the biggest


Short term...(friday through Saturday night)
issued at 143 am EDT Thursday may 28 2015

High impact weather potential: thunderstorms possible Friday
afternoon into late Friday evening. There does appear to be at least
a small risk for some of those to become severe.

Well...back we go into an active weather regime to wrap up the work
week...before things really calm down (and cool down!) Into the
weekend. As has been well advertised for several days
upper troughing digging through Manitoba/Saskatchewan is expected to
gradually drive a fairly significant cold front into northern
Michigan Friday night...with a pronounced axis of heat and humidity
arriving in the thermal ridge ahead of this feature. Exact timing of
the front still remains slightly in question...though the overall
trend of late is for a slightly slower evolution to the pattern...
suggesting we may have a decent shot to really heat up and moisten
up prior to frontal passage.

While upper forcing could be better (the majority of best qg upward
support lifts to our north)...weak height falls in combination with
strong low level frontal convergence should be enough to fire off a
band of convection to our west into the afternoon...with the
remnants of this activity pushing in our direction into the evening.
In addition...turning of the winds onshore near the usual suspect
spots as a pseudo-warm front gets stuck near The Straits suggests we
may see a bit of pre-frontal convection as well where we may locally
break initial capping. Instability on paper at least looks rather
decent...with temperatures rising well into the 70s and low (mid?) 80s
pending no cloud issues while boundary layer dew points sneak back
through the middle or perhaps even upper 60s based on upstream
readings. Middle level lapse rates look better than in recent days...
with forecast radiosonde observations hinting at upwards of 1500 j/kg MLCAPE. Throw in
the arrival of stronger middle level flow into the afternoon and an
uptick in effective shear toward 30-35 knots and the stage is set
for at least a marginal risk for severe storms during the afternoon
and evening. The main threats would be damaging winds and perhaps to
a lesser degree hail...though high freezing levels in excess of
12kft argue that threat will be dependent on stronger updrafts.
Certainly a period to watch.

While the convective threat should end later Friday night...
persistent strong and deeper layer frontogenesis laying out across
the area and the approach of another well-modeled secondary trough
axis strongly suggests a band of rain traversing the area through at
least Saturday morning. Exact ending time of this precipitation band
remains somewhat problematic...but my gut feeling is that it will
increasingly be suppressed southward with time as strong low level
ridging and drying work in from Ontario through the day. That should
(theoretically) lead to clearing skies rather quickly from north to
south...with most if not all areas just plain clear by evening and
into the night. Still quite a bit of flow just off the deck and a
decent gradient to theoretically prevent widespread cold temperatures/
frost...but still chilly with temperatures down into the 30s to low 40s.
Will continue a frost mention just in case some localized spots
decide to decouple...but really think the better risk comes Sunday


Long term...(sunday through wednesday)
issued at 143 am EDT Thursday may 28 2015

About as quiet as it gets around these parts as we wrap up the
weekend and welcome the new work week...courtesy of robust low level
ridging extending from southeast Canada down into the Great Lakes
region. Plenty of dry air to go around during the period...with some
downright comfortable weather on tap as we end the month of may and
enter the first few days of June. Should be lots of sunshine each
day with such dry air in place...with increasingly warmer but low
humidity afternoons and some quite chilly overnight temperatures. Based on
the pattern setup with the ridge axis hanging overhead right on
through Tuesday...have no doubt we are looking at several nights
with a frost threat...with the best potential Sunday night given a
very weak gradient in place...though could also envision another
night with some patchy frost Monday night as well. Maybe just maybe
we can muster some better return flow toward Wednesday with a low
end threat for some showers to make a return.


Aviation...(for the 12z tafs through 12z Friday morning)
issued at 602 am EDT Thursday may 28 2015

..showers and storms between the airports this afternoon and

High pressure this morning will shift east later today and
tonight resulting in a light southeast flow that will turn onshore this
afternoon. The resulting lake breeze convergence will set up
primarily between the northwest lower airports and apn. Scattered showers
and storms will fire off here...and track generally NE...likely
not affecting any Airport...but may be close to tvc/pln for vcsh
wording. Showers and storms will continue through the evening
before waning around midnight. Fairly deep drying will clear out
the skies for the overnight. Some light fog will be possible...but
increasing winds aloft with the development of low level wind shear will likely
limit that.


issued at 143 am EDT Thursday may 28 2015

Surface high pressure is sliding in overhead...but will exit east later
today through tonight. A light southeast flow develops...which will turn
onshore this afternoon. Scattered showers and storms will likely
lift into far Northern Lake Huron late this afternoon into the evening
hours before waning. Winds increase above the stable marine surface late
tonight...but likely not to advisory levels. A cold front approaches
the western Great Lakes Friday and it could get a little gusty...but
with it's passage Friday night...the greatest chance for advisories
will be then...Saturday and even Saturday night. Sunday maybe as Overlake stability continues to weaken.


Apx watches/warnings/advisories...


Near term...smd
short term...Lawrence
long term...Lawrence

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