Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

FXUS63 KFSD 140330

Area Forecast Discussion
National Weather Service Sioux Falls SD
1030 PM CDT Thu Jul 13 2017

.SHORT TERM...(This evening through Friday)
Issued at 337 PM CDT Thu Jul 13 2017

A ridge of high pressure will very slowly drift southeast, bringing
another cool morning. Temperatures tonight will drop again into the
50s in most locations with the coolest readings across northwest IA
and southwest MN where a few low spots could sneak down into the
lower 50s. Some of the cooler spots could allow for a little fog
development as well, but widespread low visibilities are not expected.

South to southeast winds will develop on Friday, but expected to
remain below 15 mph in most locations. Highs will also increase with
the southerly flow and range from the upper 90s in central SD to 80
to 85 over parts of sw MN and nw IA.

.LONG TERM...(Friday night through Thursday)
Issued at 337 PM CDT Thu Jul 13 2017

Friday night through Saturday night are marked by strong upper
ridging over the western U.S., with this area under northwest flow
aloft. A very weak short wave moves through late Saturday afternoon
and evening per the 1.5 PVU pressure surface. As the surface
boundary oozes southward with this wave, Saturday looks very warm
and potentially quite muggy, with light winds also noted in this
forecast area due to the wind shift. The mixed layer depth is not
overly strong on Saturday, therefore the highs of 90s in the
superblend look reasonable at this time. But as the weak cold
front moves through, Saturday nights lows will not be too warm for
this time of year and in fact, should be quite seasonal. Sunday
will be a little cooler than Saturday under the influence of high
pressure, and it will be less humid also. The exception being our
far western zones who on the periphery of the high to the east,
will once again warm up well into the 90s.

By Monday, the upper ridge extends eastward into the plains which
promises another hot day, with once again the potential for quite a
bit of humidity. Superblend`s highs were a little too cool, so
blended in a 50/50 mix of ECMWF values to warm up highs. Model
discrepancy begins by Tuesday when the GFS and GEM Global bring
another boundary/weak cold front through the area, giving some
cooler readings by mid week. Whereas the ECMWF is a full 18 hours
slower with the surface front which would mean Tuesday being another
hot and humid day. So the all blend is the way to go now, with even
the warm ECMWF cooling off some by Thursday.

In terms of precipitation, the GFS and GEM Global with its flatter
ridge and low level boundary interactions are a bit active next week
Monday night through next Wednesday. However the ECMWF is much more
capped off and thus less active. Therefore only slight chance to
chance pops are warranted at this time.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1028 PM CDT Thu Jul 13 2017

VFR conditions expected through the TAF period. There could be
some patchy fog development late tonight over portions of east
central SD, southwestern MN, and northwestern IA, though is not
expected to affect TAF sites.




AVIATION...JM is the U.S. government's official web portal to all federal, state and local government web resources and services.