Area forecast discussion
National Weather Service Gaylord Michigan
346 am EDT Tuesday may 21 2013
Synopsis...
issued at 346 am EDT Tuesday may 21 2013
A storm system in the plains will take its time moving into the
Great Lakes this week. The storm system will eventually exit east of
the region Thursday. This pattern will set the stage for continued
mild temperatures...along with several chance of showers and
thunderstorms through midweek.
High pressure will build into the Great Lakes Friday and Saturday.
This pattern will generate plenty of sun and seasonal
temperatures...over northern Michigan through the upcoming Holiday
weekend.
&&
Short term...(today through tonight)
issued at 346 am EDT Tuesday may 21 2013
Somewhat of a messy pattern out there right now...with closed
upper level low pressure across South Dakota with a shortwave
trough lifting NE through the middle Mississippi Valley. A
re-energized 800 mb low level jet of 35-45kt was ushering in the next batch of
deeper moisture (pwats approaching 1.65") up our way...and
providing the low level forcing while the upper levels were being
aided by upper divergence associated with right entrance region of
middle/upper level jet. Some isolated activity was developing along
M-55...but the main batch of showers was still working up through
Southern Lake Michigan. Strongest of storms were well south of US
across Northwest Indiana/SW lower...where latest data suggests that the
low level jet was being directed more west-east. While much of the moisture
advection may push the better rainfall off to our south...latest
VAD wind profiles are still showing a strengthening south winds
across Wisconsin.
Through the morning...the upper level jet/divergence will lift
across the western Great Lakes along with the aforementioned middle
level trough. Deep layer lift and moisture advection will result
in a period of showers and embedded thunderstorms. MUCAPE of
several hundred j/kg is still looking to not be enough for 35-45kt
of effective bulk shear to produce any widespread severe
weather...but isolated severe storms with hail are not out of the
question. Will swing this initial round of precipitation northward
through the morning. Areas of fog...locally dense off Lake
Huron...will continue to plague much of NE lower and The Straits
region. This is along and north of a near stationary frontal
boundary where easterly flow is coming off Lake Huron. I do
believe this will be a problem through a good chunk of the
day...with low clouds and some fog to gradually develop into
more of eastern upper. This to occur as the low level flow tries
to turn more southerly behind departing trough and arriving weak
surface low tracking toward The Straits.
This afternoon...of course...the big question will be how much
clearing out will we get this afternoon?..and what will the
implications be on temperatures and developing diurnal
instability?...especially of interest considering the data showing
an uncapped atmosphere with wet bulbs dropping to roughly 9kft.
Clouds are likely to linger into the afternoon behind departing
precipitation...aided by overall subsidence and height rises
expected in the middle levels. A deeper south-southwest flow is expected to
develop across northern lower...but the warm front is likely to not get
through The Straits/Lake Huron coast. This deeper southerly
flow...in theory...ought to eat away at any lingering low clouds
with later day sunshine resulting in up to 1500j/kg. Not exactly
sure on the convective evolution...but isolated to scattered
storms could get fired off in upslope flow within interior northern
lower with these storms getting shoved eastward. This is the only
foreseeable lifting mechanism (as well as the warm front). These
storms...working off better/deeper instability...would have a
better shot at producing severe weather. Large hail and damaging
winds (as wind profiles become more unidirectional) will be the
main threats...but any time there is a lingering warm
front/enhanced helicities...a tornado cannot be ruled out.
Tonight...cannot see a time to eliminate chances for showers and
storms. Strong shortwave energy drops in out of NE Canada and will
gradually allows the frontal system to sink southward. While the
800 mb low level jet is not expected to ramp up very strongly tonight...the
South Dakota upper low pivots into Iowa and will likely induce surface
low pressure that will lift into lower Michigan. Enough confidence
in my uncertainty on where exactly the exact frontal/surface low
positions will be...but can foresee either any diurnal convection
being held together into the evening...or the possibility of it
fading away. There is also the possibility for late night
nocturnal showers and storms lifting into the M-55 corridor ahead
of energy ejected from the Dakota upper low. Lots of
uncertainty...but then again...there always is with convection.
Instability doesn't look all that impressive overnight...so gotta
believe that the best shot at severe weather will be tied to later
this afternoon and into the evening.
High temperatures will range from the lower 60s in eastern upper
(cooler if stratus/fog become widespread)...to well into the 70s
and the lower half of the 80s in the mixed out bl across northern
lower. Of course...cooler in easterly flow off of Lake Huron from
roughly M-68 north.
&&
Long term...(wednesday through monday)
issued at 346 am EDT Tuesday may 21 2013
Wednesday...both the GFS and European model (ecmwf) have the surface low over S lower,
with the 500 mb low to the west, with the 500 mb jet over NE lower.
So the expectation is that the likely area of thunderstorms would be
south and east of a line from Alpena to Manistee. With less forcing
in east upper, would expect that the chances are much less.
Wednesday night...the 500 mb trough begins to move through the
forecast area with the surface low moving east of the region. This
brings in lots of cool dry air with the 70--500 mb layer relative humidity falling
to the single digits and the 850 mb moisture to around 15%. 850 mb
temperatures are also going to fall into the single digits, that the
set up for the following day, will now be chilly. Especially, since
most people have gotten used to the 70s and 80s.
Thursday...as was said in the previous paragraph, the temperatures
will end up being chilly as the 850 mb temperatures approach 0c by
00z. The only thing that we have going for US will be the mostly
sunny sky as the relative humidity in the lower and middle levels of the atmosphere
dry out to around 10%. This will allow US to warm under full sun.
With the surface high building in the region, winds should begin to
settle down a bit as the gradient begins to slacken. Overnight, as
the temperatures dip toward freezing and the winds diminish, will
expect that the frost will be an issue. At this point, have patchy
and areas of frost, but it may have to be widened as the
temperatures have a chance to fall below freezing if core of the
high sets up over like the European model (ecmwf) shows.
Extended (friday through monday)...Friday, high pressure builds into
the region and keeps the forecast area dry. Saturday, the high
pressure remains in place and continues to keep the place dry.
Sunday, high pressure continues, so the weekend itself looks good
for getting outside. Monday, over north Michigan looks dry. If the European model (ecmwf)
is right then the day should turn out mostly sunny.
&&
Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1201 am EDT Tuesday may 21 2013
Nearly stationary boundary continues to dissect the taf sites
from northwest to southeast. This is expected to keep pln and apn
in the low clouds and fog...dense at apn overnight with patchy fog
at tvc and mbl. Additional showers and thunderstorms are expected
to move into mbl and tvc early this morning and spread into pln
and apn late. More showers and thunderstorms are likely during the
day as well.
&&
Marine...
issued at 346 am EDT Tuesday may 21 2013
Warm air/moist over Cold Lake waters will keep winds at Bay...but
areas of fog and low clouds will be seen across much of Northern Lake
Huron and The Straits/Lake Superior into today. Periods of showers
and storms will be common as well...due to a near stationary
frontal zone stretched over northern lower. This front will dive south
of US Wednesday...allowing a tighter pressure gradient to develop
Wednesday night through Thursday. As colder air pours in...the
stability weakens and Small Craft Advisory gusts look like a good
bet. Higher pressure settles in Friday and into the weekend.
&&
Apx watches/warnings/advisories...
Michigan...none.
LH...none.
Lm...none.
Ls...none.
&&
$$
Synopsis...jl
short term...South Dakota
long term...jl
aviation...as
marine...South Dakota
