Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 311103
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
603 AM CDT TUE MAY 31 2016

.SHORT TERM...(Today and Tonight)
Issued at 403 AM CDT Tue May 31 2016

Convection shifting east this morning with northwest flow in place
behind. Overall not expecting any additional thunderstorm activity
today with the exception of parts of northwest Iowa. This area will
remain on the tail end of the instability as the upper level wave
wraps up to the north. With weak convergence and marginal, mainly
less than about 750 j/kg cape, any showers or thunderstorms that can
develop will not be severe. Another area to watch will be in central
South Dakota where the main wave might allow isolated development
along a weak trough but at this time it looks to remain capped so
will not include any low end chance. temperatures will be a bit on
the cool side, especially with a marginally breezy northwest wind.
Highs will mainly be in the 70 to 75 degree range.

Mostly clear skies tonight and fairly light winds will allow
temperatures to cool nicely, especially across northwest Iowa where
winds will be lightest. Along highway 14 winds should be closer to
10 to 15 mph so the radiational drop will not be as strong. Lows
mainly 50 to 55.

.LONG TERM...(Wednesday through Monday)
Issued at 403 AM CDT Tue May 31 2016

Wednesday into Wednesday night looks fairly cool, and a bit breezy
during the day. Highs will likely only reach the upper 60s to lower
70s in most locations. Not a while lot going on other than a little
afternoon diurnally driven cumulus and there will not be enough to
take away from a mostly sunny to partly cloudy day. The only spot
where clouds could be a bit more extensive will be along the highway
14 corridor. By Wednesday night high pressure will settle in a winds
will become fairly light. Lows should range from about 45 to 50
degrees.

Through the day Thursday, will gradually see an increase in return
southerly flow as the cool low level ridge shifts eastward. Moisture
will likewise increase, while somewhat steeper mid level lapse rate
will overspread the area. There is just enough elevated theta-e
advection by very late morning to bring a minimal pop into south
central SD, and at last spotty activity should continue to spread
gradually north/east with advective gradients through the afternoon
as weak wave begins to push through the central Dakotas.  Lack of
widespread precip threat and perhaps up to some broken cloudiness
should allow temps to climb into the mid 70s to lower 80s.

Area of low precipitation chances should continue to build north and
east Thursday night as main northwest flow trough digs into the far
western high plains by early Friday. Southerly flow should keep lows
much milder, in the upper 50s to lower 60s.

With watching convection early in this overnight, have pretty much
gone straight with extended initialization grids. Fortunately, there
is but one slightly more significant forecast challenge to the
period, that being wave forecast to dig toward the eastern
Plains/Great Lakes Friday and Saturday. GFS is much more aggressive
digging trough westward, closing off a much slower moving system
across Minnesota and Wisconsin.  As a diggy outlier, have moved away
from this solution which kept rain chances in all weekend in
southwest Minnesota and northwest Iowa. Best precip chance will come
by Friday afternoon and evening, as wave digs through toward
Minnesota and pushes a cold front across the area. For now, have
kept mainly scattered level pops. Will have to watch as shear
parameters have potential to be strong enough to support organized
convection, and instability should be quite sufficient for decent
updrafts. Could be a few lingering showers through eastern areas on
Saturday with cyclonic flow and cooler readings aloft, but again
have trimmed back areas between James River and just east of I-29
per favor toward more progressive solutions. The remainder of
Saturday through Monday appears quite pleasant in terms of near to
slightly above normal temperatures and dry conditions.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 602 AM CDT Tue May 31 2016

Hit and miss showers and thunderstorms over parts of northwest
Iowa today, otherwise VFR through the period.

&&

.FSD Watches/Warnings/Advisories...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...08
LONG TERM...08/Chapman
AVIATION...08



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