Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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691
FXUS63 KFSD 291654
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1154 AM CDT FRI JUL 29 2016

.SHORT TERM...(Today and Tonight)
Issued at 335 AM CDT Fri Jul 29 2016

Seeing scattered showers through our south central SD zones very
early this morning as a subtle pv anomaly slides from central SD
into eastern NE. This feature will to continue to shift off to the
south and east with short term models indicating this activity
waning across our area through the morning hours. Otherwise, the
remainder of the day looks to be mainly dry over our area with
temperatures remaining just below normal. Highs will range from mid
70s over a good portion of northwestern IA and southwestern MN to
the lower 80s through the James River Valley/MO River Valley.

Tonight, the rain threat will increase once again over south central
SD later in the night - with increasing theta e advection as a weak
low level jet develops over the central part of the state. With a
weak southeasterly low level flow developing across the area
overnight, some guidance is suggesting stratus formation east of
Interstate 29 toward Saturday morning. Low temperatures will again
run from the upper 50s to lower 60s.

.LONG TERM...(Saturday through Thursday)
Issued at 335 AM CDT Fri Jul 29 2016

Expect any early morning convection west of the James River Saturday
to diminish during the morning as subtle wave exits. Modest increase
in instability Saturday afternoon, but additional forcing appears to
hold off east of the Missouri River until Saturday evening. Saturday
night then looks to be best shot at scattered storms through the mid
range portion of the forecast, with modest warm advection/low level
jet ahead of a weak mid level wave. Will carry precip chances again
Sunday night/Monday, mainly north and east, as models are pointing
to another wave/stronger warm advection. Stronger wave seen in some
solutions appears to be convective feedback from afternoon/evening
activity in the western Dakotas, so despite higher QPF output from
some models which develop possible MCS dropping into central SD late
Sunday night, will keep chances on the lower end due to conditional
development and inconsistencies in track of the wave. Saturday will
be the last day in this stretch of cooler/less humid conditions, as
warmer air and higher dew points will begin to work their way into
the region starting Sunday.

Longer range Monday through Thursday begins with little in the way
of organized precip chances as weak waves continue to track over
top of broad and flat upper ridge. Main story early next week will
be the return of heat/humidity, which should push heat index values
near 100 through parts of the James/Missouri River Valleys Monday,
and a few degrees higher on Tuesday. Pattern shift begins midweek as
upper trough pushes across the Rockies and into the High Plains on
Wednesday. This should bring our next chance of at least scattered
storms as associated cold front moves through the region late
Wednesday and Wednesday night. A little better mixing potential
ahead of the front Wednesday should ease humidity levels slightly,
though some locations still likely to see heat indices nearing 100.

Main upper system will continue to move east across the Canadian
Prairies through Thursday, dragging northern end of the cold front
eastward through the Northern Plains. However, southern end of the
front gets hung up over eastern Colorado/western Kansas as strong
upper ridge over southeast CONUS limits progression, and thus the
boundary will linger near northwest Iowa through Thursday. Thus will
hang onto a chance of storms over our southeast, while drier air
works into northwest portions of the area.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1152 AM CDT Fri Jul 29 2016

A scattered CU field will persist into the early evening hours
before dissipating. Otherwise VFR conditions are expected into the
early morning hours of Saturday. As winds turn light and variable
after midnight, we may see light fog develop over northwest Iowa
and advect westward towards KSUX/KFSD. Will introduce a low MVFR
ceiling and visibility through mid-morning, with VFR conditions
prevailing by mid-day.

&&

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

$$

SHORT TERM...JM
LONG TERM...JH
AVIATION...Dux



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