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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
1224 PM CDT Tuesday may 5 2015

Update...
issued at 1216 PM CDT Tuesday may 5 2015

Updated to include 18z aviation discussion below.

&&

Short term...(today and tonight)
issued at 340 am CDT Tuesday may 5 2015

Showers and thunderstorms have been confined well south over Iowa
and Illinois overnight. Dry northeast flow continues over our
neck of the Woods as high pressure drifts over the u.P. Of
Michigan. Winds will begin to turn southeast and increase this
morning... bringing some of the moisture back into the area.
Models appear a little too quick bringing the higher dew points
back...but by late afternoon 50s are certainly possible across southern
and western Minnesota. Cannot rule out a few showers developing in these
areas...but chances look pretty low with weak forcing. The better
chance for rain will come tonight as the main surface warm front
lifts north. Still...as unidirectional flow takes shape...
frontolysis will limit forcing. Models show rather meager quantitative precipitation forecast
tonight...certainly compared to what they were showing a few days
ago. The WRF-nmm and WRF-arw advertise only a thin line of showers
lifting north with the front...so no meaningful rainfall
unfortunately. Kept probability of precipitation in the chance category for now until
confidence in timing increases.

Given the lack of middle cloud cover in place now and how there could
be several hours of sun before they move in...particularly
across central Minnesota and northwestern WI...raised highs today several
degrees.

Long term...(wednesday through monday)
issued at 340 am CDT Tuesday may 5 2015

The long term concerns remain the timing of the ejection of
southwest Continental U.S. Short wave Wednesday night into Thursday night.
Then the timing and development of the next short wave that lifts
into the region later in the weekend and into early next week.

The models continue to have a a tough time with the dry air in
place over the western Great Lakes. Model trends indicate that
this will gradually become overcome by somewhat deeper moisture as
the warm front lift into the area during the day Wednesday. Will
continue the chance probability of precipitation for Wednesday morning...then increasing
to likely over the western County Warning Area during the afternoon with the
approach of better moisture and forcing with the short wave. The
best shot of precipitation comes in for Thursday as the upper
trough is forecast to lift northeast over the area. Models are in
good agreement in timing of this feature and its attendant cold
front. This should scour the rain threat from wet to east Thursday
night. Will leave small chance probability of precipitation into the far eastern County Warning Area into
Friday in case trough slows a bit. Expecting more clouds as this
system moves through and this will likely hold temperatures down
somewhat. Highs in the 70s look to be OK for the time being. If we
did happen to see more sunshine...we may warm into the lower 80s
to the south.

The longer term trends indicate another decent wave lifting
northeast...affecting the region mainly Sunday and Monday. This is
high variability in the strength and movement of the surface low
associated with this wave. The 00z European model (ecmwf) developed a deep surface
low...occluding to the north over Minnesota late in the weekend. The GFS
was much farther south and weaker. The European model (ecmwf) has trended colder
towards may 11 as well...which would parallel the trend on the cfs
v2. The 18z run really dropped temperatures...with highs
struggling to warm to around 40 on the 11th. Some significant quantitative precipitation forecast
as snow forecast for msp as well. At the moment...the European model (ecmwf) has
the snow over the Dakotas for this period. We wont go as cold as
these models indicate. National guidance has the low tracking
closer to the gefs mean or across Iowa/Missouri through next
Monday. Definitely colder than average...with highs struggling to
warm through the 50s at that time...which could set up at least a
portion of the area for frost early next week.

&&

Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1216 PM CDT Tuesday may 5 2015

VFR to start but as a warm front approaches from the S...lower clouds will
steadily take over. Low scattered clouds with midlvl ceilings will
precede MVFR ceilings late this evening through the overnight hours
into tmrw with the front. Scattered rain showers look to develop
by the pre-dawn hours but will be more of the hit-and-miss variety
rather than more sustained rains...which look to come middle-to-late
day Wednesday. Modest improvement may come with the rainfall but
ceilings still look to hold in the MVFR range while visibility is not
expected to drop to below 5sm. Winds will be solidly southeast throughout
with speeds in the 8-15 knots range.

Kmsp...will look for ceilings to remain above the 1700ft threshold
through this afternoon and evening...then drop below much of the overnight
period. As precipitation comes in...some of those low clouds will be
washed out...allowing for MVFR ceilings to continue but just above
the 1700ft mark. No visibility restrictions expected until tmrw afternoon and
chances for thunderstorms are too low for inclusion at this time.

/Outlook for kmsp/
Thursday...MVFR conds likely with IFR conds possible in shra/tsra.
Winds S 15-25 kts.
Friday...VFR. Winds northwest 5-10 kts.
Sat...VFR. Winds NE 10-15 kts.

&&

Mpx watches/warnings/advisories...
Minnesota...none.
WI...none.
&&

$$

Update...jpc
short term...borghoff
long term...dwe
aviation...jpc

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