031 
FXUS63 KFSD 100831
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
331 AM CDT Wed May 10 2017

.SHORT TERM...(Today and Tonight)
Issued at 331 AM CDT Wed May 10 2017

A broad area of showers and isolated thunderstorms are currently 
lifting through central and eastern NE early this morning in 
association with a shortwave tracking through the region. Also 
seeing showers over western/central SD supported by upper level 
divergence with a jet streak sliding across northwestern SD. These 
two areas of precipitation will essentially merge over our area 
during the morning hours, becoming focused in areas south of 
Interstate 90 with increasing mid level frontogenesis/upper level 
support provided by the aforementioned jet streak which will track 
across northern SD into the afternoon. Elevated instability will be 
confined to our lower IA zones early, so kept isolated thunder there 
through the morning hours. Some uncertainty on the northern extent 
of the precipitation shield through the morning as it will be 
fighting dry low level air in a northeasterly flow. Showers will 
then taper off from west to east during the afternoon as forcing 
pulls off into MN. Temperatures are also rather tricky today 
dependent on where rain occurs and where clouds hang on the longest. 
At this point anticipating highs into the upper 60s and lower 70s 
through the Chamberlain/Huron/Brookings/Marshall corridor where 
there is more chance of breaks in the clouds, while to the south of 
this area highs will probably only make it into the lower 60s.

Any rain will have ended by early this evening with clouds 
decreasing overnight. With winds becoming light it will be a cooler 
night with lows in the 40s across the entire area.


.LONG TERM...(Thursday through Tuesday)
Issued at 331 AM CDT Wed May 10 2017

Cooler and drier air will settle into the area on Thursday providing 
a sunny day with north winds about 10 to 15 mph. High should be in 
the mid 60s to lower 70s.

Thursday night into Friday will see surface ridging move through 
with southerly flow developing on Friday. Thursday night lows may 
fall a little lower than forecast if winds go calm overnight. Friday 
should prove to be a very nice day with south winds only gradually 
increasing and highs in the 70s.

Upper level ridging will move across the area on Saturday into 
Sunday which should bring dry conditions. This will allow for a 
couple of nice, warm days with highs in the 70s to lower 80s. While 
it should not be windy, south winds should average about 15 to 25 
mph on Saturday and 10 to 20 mph on Sunday.

A fairly weak wave scrapes by to the northwest of the area Sunday 
night into Monday and will bring a small chance for showers and 
thunderstorms. At this time not banking on too good of a chance. 
However this should keep a pretty mild pattern in place so lows will 
be from the mid 50s to lower 60s. 

The best chance for showers and thunderstorms will come Monday night 
into Tuesday morning as the models are fairly agreeable that a 
stronger piece of energy will eject into the northern and central 
Plains. Suspect that if we can get storms going a few of them might 
become severe.

Tuesday night into Wednesday hinting that while upper level support 
will not be as good, the low level boundary might linger around the 
area and could provide an increasing threat for showers and 
thunderstorms on Wednesday.


&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1024 PM CDT Tue May 9 2017

Convection beginning to blossom over Nebraska, Kansas, and
Colorado this evening will continue northward overnight, likely to
arrive at the terminals at or just after daybreak. Meanwhile
secondary energy dropping southeast out of Montana will drive a
separate area of showers southeast gradually merging with the
southern cluster of showers/thunderstorms Wednesday morning. 

Generally VFR conditions are expected as rain moves through, with
minimal or brief visibility restrictions. Sioux City may be
impacted by a bit of MVFR ceilings around mid-day as initial band
of rain slides just north. However, skies will gradually improve
through the afternoon and into the evening as dry air pushes into
the area from the northwest. 


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...JM
LONG TERM...08
AVIATION...Dux