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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
1124 PM CDT Wednesday Apr 23 2014

Update...
issued at 1101 PM CDT Wednesday Apr 23 2014

Updated for 06z aviation discussion below.

&&

Short term...(this evening through thursday)
issued at 348 PM CDT Wednesday Apr 23 2014

Rain...heavy at times...isolated thunder...and wind will be the
main concerns over the next 24 hours. From Morris to Fairmont...we
have seen sustained winds 27-29kts with gusts easily into the middle
30s. With the storm still approaching and the tightest gradient
yet to move into SW Minnesota...the Wind Advisory will remain in effect
until its expected expiration at 7 PM. Next issue is the rain
forecast...with an initial band moving through east central Minnesota as expected
this afternoon...and more on the way. Scattered convection is beginning
to develop in SW Minnesota...and this will be the trend as we head
through the afternoon as it spreads NE. The main show will commence
overnight as a lead shortwave moves into S Minnesota ahead of the main
trough hanging back in the western Dakotas. There will be a
significant area of possibly severe convection developing this
evening in S South Dakota/east Nebraska/East Kansas close to a low pressure center and
associated cold front. This convection will lift into Iowa and far
southern Minnesota after midnight then into west central WI as
ingredients for heavy rain come together. Moisture transport is
maximized in that area along with precipitable waters exceeding 1" as a closed
700 mb low moves overhead. Our current forecast paints greater than 1" of
rain...mainly after midnight tonight through middle-morning on Thursday.
Higher rainfall amounts are certainly possible where any training
cells or thunderstorms develop. Rain will linger for much of the
day as the parent upper level wave moves in from the Dakotas. In
terms of thunderstorms...there is meager instability developing
this after...especially in a clear slot in eastern South Dakota...but as the
afternoon progresses...the expected convection in Nebraska/Kansas will "steal
our thunder" in terms of dynamics for widespread thunder this far
north. Isolated T has been maintained in the forecast for tonight and
the first half of Thursday...especially as the main upper level wave
comes through this evening. Despite this upper support...
convective parameters are pretty unimpressive with best Li/S
staying above zero with very little cape. As mentioned above...the
Mode will transition to a heavy rain threat for the second half of
the night. Clouds will continue to thicken and lower overnight...
and along with a steady breeze...temperatures from not vary significantly
over the next 24 hours

Long term...(thursday night through wednesday)
issued at 348 PM CDT Wednesday Apr 23 2014

An occluded front will drive east of the forecast area Thursday night
bringing much of the rain to an end. Lingering small probability of precipitation remain
across the far northern reaches of the County Warning Area at the base of the
upper trough/low through Friday. Quite a range in high
temperatures forecast for Friday with sunshine across the Minnesota
River Valley to mostly cloudy conditions to the north and east.
Highs from the middle 60s to the lower 50s forecast respectively.
This will be the last near normal day on highs as temperatures
drop well below normal through the rest of the long term. This is
due to the Rex block developing over US during the weekend and
persisting through much of next week. The trend today on both the
GFS and European model (ecmwf) is for the upper low being a little farther south
from Sunday through Tuesday. There still remains high chances for
precipitation from Saturday night through Monday...especially in
the Minnesota River Valley where deeper moisture and better forcing exist
to the northeast of the upper low. This southward displacement
with the upper low allows some pretty chilly air into the forecast
area for Sunday through Tuesday. Forecast highs in the middle 40s
to lower 50s are common with lows around 30 to the middle 30s.
Anyone or businesses setting plants out this weekend as well as
early next week will need to be cognizant on the frost/freeze
potential. The normal high for the end of the April here in the
Twin Cities is in the lower 60s with the low near 40. This cold
scenario kept the mention of snow in the forecast...primarily for
Monday night and Tuesday. Nothing significant is expected with
regards to snow accumulation. Diminishing precipitation chances
are forecast for Tuesday night and Wednesday with lows/highs
remaining well below normal.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1101 PM CDT Wednesday Apr 23 2014

Little to no precipitation currently affecting all weather forecast office mpx terminals at
24/06z initialization time but another round of numerous to
widespread rain is organizing over far southwestern Minnesota and going upstream
from there. This larger area of precipitation will overspread the
coverage area approaching daybreak and persist through midday Thursday.
Short-term models continue to indicate a period of moderate-heavy rain
around daybreak and continuing into early afternoon...which may drop visibility
into IFR rain due to precipitation intensity. As for ceilings...all sites are
VFR but have shown a lowering trend so have delayed the onset of
MVFR ceilings from the 00z set per these trends but am still xpctg
ceilings to drop to MVFR by 09z-10z and remain as such into late afternoon.
Confidence too low at this time to try to pinpoint convection at any of
the terminals despite the presence of marginal instability and an
incoming cold front so have omitted cumulonimbus/ts at this time...although it cannot be
entirely ruled out. Conds improve by late afternoon through the evening hours
tmrw with the frontal passage. Winds to remain NE overnight through much of the
day tmrw then swing around to eventually become west to northwest tmrw evening
with speeds generally 10-15 knots through tmrw afternoon then diminishing.

Kmsp...VFR conds to start then MVFR ceilings likely in the pre-dawn
hours along with another round of fairly solid rain. Rain will
persist through late morning...with a period of moderate-heavy rain likely during
the morning push which may drop conds into IFR range. Precipitation
gradually abates by early-to-mid afternoon and conds improve from
there. Winds to continue from the southeast through late morning...then as a
cold front moves through...wind directions will swing around to SW by middle
afternoon then to west-northwest tmrw afternoon and evening. Speeds will be greatest during
the first 6-9 hours of this taf set...then gradually diminish to
5-10 knots.

/Outlook for kmsp/
Friday...VFR. West winds 10-15 knots becoming north.
Sat...VFR. NE winds 10-15 knots.
Sun...mainly VFR. MVFR conds possible in -ra. East winds 15-25 knots.

&&

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

$$

Update...jpc
short term...jca
long term...rah
aviation...jpc