Area Forecast Discussion
Issued by NWS Sioux Falls, SD

Current Version | Previous Version | Text Only | 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 42 43 44 45 46 47 48 49 50

000
FXUS63 KFSD 262316
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
616 PM CDT SUN JUN 26 2016

.SHORT TERM...(This evening through Monday)
Issued at 211 PM CDT Sun Jun 26 2016

Main forecast concern in the next 24 hours is thunderstorm chances.
Both GFS and NAM show an area of frontogenesis developing near the
Nebraska and South Dakota border by this evening. As frontogenesis
intensifies, enough moisture will move north to produce 900 mb LI`s
as low as -4 after sunset. There is not a significant wave to
enhance lift along the boundary but there is also not significant
large scale subsidence so expect the frontal circulation to be
strong enough to overcome the weak cap resulting in convection near
the state border by midnight. There is enough instability present
downstream toward Sioux City to keep convection going through the
night and have a 40 to 50 percent chance in the Missouri Valley west
of Sioux City.  Effective shear is generally less than 30 kts and
lapse rates are less than 7 C/km so instability is not that
significant. Therefore no severe weather is expected.  The second
question is how far north convection will go.  Some high resolution
models, such as the NCAR 3 km ensemble and HRRR are showing
convection as far north as I-90 overnight. With the 925 boundary
closer to the Missouri River the expectation is that storms will
remain south of I-90. With dry air and light winds overnight lows
will be in the 50s north of I90 to the mid 60s with more clouds in
the Missouri Valley.

On Monday, expect that convection will continue but storm
propagation will be southeasterly which should result in convection
moving into Nebraska and west central Iowa by early afternoon. As
the boundary moves south, the chance for thunderstorms will end and
skies will become partly cloudy.  Cooler air will move southward
during the day, especially in the Minnesota River Valley and highs
in southwest Minnesota will be in the mid to upper 70s. Warmest
temperatures will be in the mid 80s in the Missouri Valley.

.LONG TERM...(Monday night through Sunday)
Issued at 211 PM CDT Sun Jun 26 2016

Northwesterly flow aloft will continue to produce slightly cooler
than normal temperatures, along with periodic rain chances into next
week.

Monday night into Tuesday: High pressure will slide southeast
through Minnesota during the overnight hours, however weak
isentropic lift may produce a few showers after midnight across
central portions of South Dakota. Again, quiet weather anticipated
for most locations on Tuesday. Models are hinting at the potential
for an MCS to form well west of the MO river.

Tuesday night and Wednesday: The first large scale precipitation
chance for the CWA falls late Tuesday night into Wednesday as a
shortwave trough moves through the Northern Plains. Models remain
all over the place with individual waves in the progressive NWLY
flow. Favor the ECMWF/GEM over the GFS/NAM, which suggest increasing
rain chances towards midnight as upper support increases and the
LLJ focuses over the western half of the CWA.

Thursday: Some questions on a few diurnal storms late Wednesday
afternoon, with the next best chance for precipitation arriving very
late Wednesday night and continuing through Thursday as a frontal
boundary drops southward through the region. Again, timing issues
remain with this features, making it difficult to focus on a
specific 6 hour period where precipitation would be higher than
other periods.

Friday-Sunday: With upper troughing reinforced over the Great Lakes,
and high pressure dropping southward into the region, there appears
to be more opportunities for dry conditions than wet conditions in
the extended portions of the forecast. Cooler high pressure will
hold temperatures near to slightly below seasonal normals, rather
comfortable for the first days of July.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 613 PM CDT Sun Jun 26 2016

primarily VFR conditions through the TAF period. There is a chance
that scattered thunderstorms will develop through the Missouri
River corridor overnight, possibly affecting KSUX toward 12z on
Monday.

&&

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

$$

SHORT TERM...Schumacher
LONG TERM...Dux
AVIATION...JM


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