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Area forecast discussion 
National Weather Service Gaylord Michigan
627 am EDT Wednesday may 27 2015

Near term...(today through tonight)
issued at 138 am EDT Wednesday may 27 2015

Synoptic pattern and observations:

Early this morning...surface low pressure was lifting up toward eastern
Upper Michigan. The associated warm front...deeper channel of Theta-
east...steeper lapse rates aloft/ well as all primary
forcing mechanisms (llj/waa...upper divergence...and dpva) have all
lifted north and east of here. The atmosphere remains mild and moist
in the bl...while there has been some drying/subsidence aloft. Any
new activity has been isolated and short-lived. Looking upstream
however...shortwave troughing still resides in Wisconsin with a cold
front extending back through northwest Illinois. There are hints of weaker low level jet
forcing and a secondary axis of higher Theta-E/slightly steeper
lapse rates aloft ahead of the cold front. Vorticity maximum was wrapping
around the base of the trough and lifting toward lower Michigan.
Scattered showers have been able to sustain themselves as they
crossed northern Illinois and into Southern Lake Michigan. Total forcing was rather
weak and diminishing with the lack of jet support and any serious
DPVA. Deeper moisture was seen on the northwest flank of the surface low with
deformation forcing more widespread rains across northwest WI and Upper

Synoptic pattern evolution and associated weather:

The shortwave trough and associated surface low pressure and cold front
lift through the region today...while the deeper moisture and
deformation shears NE across primarily the northwest County Warning Area. The secondary low
level jet is really out of here by daybreak...while the slightly
steeper lapse rates slide across the far southeast County Warning Area. Nothing to get too
excited about here...but deepening low level moisture arriving along
and behind the front will bring cloudy skies and a period of light
rain and drizzle to much of the region....with the potential for
isolated/scattered showers across NE lower prior to the front (aided
by perhaps a differential heating boundary? The best chances for
rain will be across western chip/Mack counties in the deepest
moisture and deformation/total deep layer forcing maximum. A very weak
vorticity maximum and surface cold front undergoing frontolysis lays out across
eastern upper overnight...but only think there may be a small chance
for additional lighter showers drifting into Northern Lake Michigan later
tonight. These may originate from late afternoon diurnally driven
showers across central upper and NE WI. Continued middle level height
rises through the night and diminishing diurnal instability is more
than likely to allow any showers to dissipate before arriving in the
northwest County Warning Area.

High temperatures today will vary from well into the 70s across far NE the lower 60s across western chip/Mack in locked in deep
low level moisture/clouds. Lows tonight in the 50s most areas with
periodic clouds.


Short term...(thursday through Friday night)
issued at 309 am EDT Wednesday may 27 2015

High impact weather: thunderstorms for Friday through Saturday

Forecast challenge: severity of thunderstorms Friday
afternoon/Friday evening.

(5/28)thursday...NAM and GFS show that there is a chance for showers
in the afternoon as the moisture pools in the lower levels on the
soundings in NE lower. The European model (ecmwf) shows that that nothing happens,
although the computed surface lifted index shows -2c on the European model (ecmwf) as it
does on the GFS. So will go with a slight chance in NE/NC lower as
that moisture and the lake breeze boundary begin to pool the
moisture in the region. However, after 00z, the instability should
lower enough for the chance of showers to lower as well. Overnight,
the cold front and the surface low begin to move into the boundary
waters region, and the Hudson Bay high, puts enough dry air into the
region to delay the rain from getting into the forecast area, until
possibly the last moment early Friday morning.

(5/29)friday...after 12z, the chance for showers and possibly
thunderstorms begins to increase as the front begins to approach the
forecast area. However, it looks like the best time for the rain
will be in the afternoon and early evening as the front is just
crossing Lake Michigan. Models show that there could be -4c lifted
index by 00z, so there could be a chance for some decent
thunderstorms especially with the highs expected to be in the lower
80s. Just looking at some basic ideas like the 500 mb winds (around
40 knots) the possibility of some shear to get the storms to be
strong. Overnight, the front passes through the forecast area, with
the European model (ecmwf) showing the frontal passage a little slower than the GFS
with the rain still in east upper by 12z.


Long term...(saturday through tuesday)
issued at 309 am EDT Wednesday may 27 2015

If the front is slower on Saturday morning with the European model (ecmwf) than
the GFS, then thunderstorms may be likely, so have left that in
for now. However, high pressure builds into the region on both
models and the area should remain dry through Monday night. On
Tuesday, the models are in conflict as the GFS pushes moisture and
an approaching front into the upper Great Lakes. This would bring
showers to east upper. However, the European model (ecmwf) shows that the the surface high
(hudson Bay type) is retreating east. This tends to be a drier
pattern than the GFS would suggest. Will continue the showers in east
upper for now, but think that the European model (ecmwf) may be on a better track.


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 623 am EDT Wednesday may 27 2015

..stratus and light rains moving in...

Surface low pressure lifts through Upper Michigan/Ontario through the
day...and a cold front and deeper low to middle level moisture works
into primarily the northwest lower airports. This will bring a period of
IFR/MVFR ceilings...and rain/drizzle issues starting near noon or
shortly thereafter. Across Alpena...the deeper moisture does not
roll in until this evening...and can see isolated showers possibly
roaming through today. Sort of a nebulous sky forecast through
the night but believe the trend is for a diminishing clouds but
cannot totally rule out some additional stratus and fog developing

Low level wind shear to end with mixing commencing. Gusty SW winds mainly at apn
today. Winds tending to turn more west...and lighter across northwest
lower. Light winds Wednesday night.


issued at 359 am EDT Wednesday may 27 2015

Advisory level gusts have shown up in more marine observations
over the last couple of hours...across northwest coastal
convergence regions. Have issued a Small Craft Advisory through
15z until winds are expected to start dropping off a bit. A cold
front then passes through during the day...and the focus shifts
to primarily Whitefish Bay and Northern Lake Huron nearshores for
possible advisories. Right now...due to the stability over the
lakes and marginal nature of the wind speeds...will hold off on
advisories there. Warm and moist air over the lakes will continue
to result in areas of fog.

Higher pressure then takes over later tonight and into Thursday. A
chance for advisory level gusty SW winds develops Thursday night
into Friday...but the best chance by far for wind/wave issues will
be Friday night into Saturday behind a much stronger cold front in
a more abrupt wind shift out of the northwest.


Apx watches/warnings/advisories...
Lm...Small Craft Advisory until 11 am EDT this morning for lmz323-342-



Near term...smd
short term...jsl
long term...jsl

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