A Sunny Day!

We have expectations of a sunny day today with highs in the upper 60s to lower 70s through tomorrow which will be well above normal for a change. Showers and thunderstorms are expected Wednesday and Wednesday night which could become severe. This will be followed by another cool-down towards the end of the week which will return us to normal or slightly below normal temperatures.

The SPC continues to place us in the slight to marginal convective outlook for tomorrow with the enhanced outlook south of the border.

SPC Synopsis

 An upper trough/low will continue to eject from the Plains across
   the MS Valley and into the Midwest and Great Lakes region on
   Wednesday. The southern portion of the trough will likely acquire a
   negative tilt as it moves over the mid MS Valley and Midwest through
   the day. A 60-80+ kt mid-level jet will also overspread these
   regions, with a broader area of enhanced mid-level winds
   encompassing much of the surface warm sector. A surface low over the
   Upper Midwest Wednesday morning is forecast to develop eastward over
   the Upper Great Lakes through the day. An attendant cold front will
   sweep east-southeastward over much of the Midwest, lower/mid MS
   Valley, and Southeast through the period.

Forecast Discussion

- Storm System Tuesday Night through Wednesday

  A warm, windy day today with warmer then normal temperatures
across southern lower Michigan. The upcoming system is best
described in three waves.
 The first will be the advance of a warm front which will bring
showers and thunderstorms tonight into Wednesday morning. The
juxtaposition is that that the gusty southern winds that will
mix down very warm and dry air today, will bring warm, moist
summer like air tomorrow. Winds will continue to increase tonight
into tomorrow with decent directional and speed wind shear
through the low levels overnight. A 55 kt LLJ will coincide the
advance of the warm front.

The second wave is currently indicated by the latest HREF with 500
to 1000 J/Kg CAPE Wednesday morning. A 500 mb short wave will be
the spark for the second wave of thunderstorms Wednesday. This
should allow for showers and thunderstorms across southwest
Michigan. The gusty low level winds and instability will mean
damaging winds the main threat. SPC has a slight risk for most of
SW Michigan for Wednesday. The best QPF tonight into Wednesday
will coincide with the strongest low level jet. Expect widespread
half an inch to an inch of rainfall with locally amounts possible,
especially along US 131 north of Big Rapids.

 The third wave will be due the cold front that will sweep through
the region Wednesday evening. This will bring more instability
with a line of thunderstorms with the leading edge having bowing
segments. The strongest winds will be south of Michigan but strong
to severe winds Wednesday eve remain possible.

- Gusty winds Thursday

A large upper level low will then situate itself over southern
Canada and the Upper Midwest. A strong post frontal gradient then
could bring winds upwards of 40 kts. A dry slot that will allow
for copious amounts of sunshine will allow gusty upper level winds
to mix to the surface That gradient will persist through daytime
Thursday. A wind advisory remains probable

- Colder air on the Horizon

 While warm summer like convection will dominate the pattern the
next few days, cooler temperatures will return in time for Easter
weekend. Lows on Sunday should be in the 20s with highs in the
upper 40s.

Here is the previous update discussion focusing on the long term.

 A week of colder than normal weather following this warm up the
first half of the week. This is well supported by the GFS and
ECMWF ensembles. For at least the past week the ECMWF have
featured the cold period from Thursday to next Saturday (23rd) on
every model run since the 5th of April. The GFS is no different in
that regard. For that matter, the Canadian model ensembles have
been and continue to feature this week or so of colder than normal
tempeatures coming up.

Currently at GRR our monthly temperature anomaly is (as of
midnight last night) was 4 degrees below normal. Given the short
nature of our current warm up and the lenght of the cold anomaly
expected, it seems more than reasonable to expect April to
continue to average colder than normal. Curiously, if you look
back at all of the years we had a moderate or stronger La Nina
during the winter (we did this year) since 1950, we have had 15 of
them. Only 20% of those Aprils were warmer than normal. Curiously
May`s odds of being warmer than normal are not high, only 27% of
those May`s were warmer than normal. Another aspect to that is
that our mean (at GRR) first 70 date is the 4th of April. If we do
not get to 70 on Wednesday, we may have to wait until the last
week of the month or longer.

Since this year we are getting this as a result of a series of
closed upper lows, this also has resulted in above normal
precipitation and we do expect another precipitation event during
the early to middle of part of next week. Actually 40 out 50 of
the ECMWF ensembles give us measurable snow in the Mon to Wed
time frame of next week. The GFS ensembles are not as strong on
this idea but still have nearly 15 of the 30 members forecasting
snow early next week.