526 
FXUS63 KFSD 092028
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
328 PM CDT Tue May 9 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 327 PM CDT Tue May 9 2017

Weak wave moving across central SD this afternoon, with scattering 
of light showers from south central into southeast SD.  Dry air at 
lower levels has been advecting into much of the area on northerly 
winds, which has somewhat neutered initial edge of precipitation to 
a few sprinkles.  CAMS a little more aggressive with coverage and
persistence of precipitation across the northern CWA and additional 
development along the vort tail back toward northeastern NE, but 
even some of the lower resolution solutions follow generally along 
the path.  As this weak wave shifts east of the area this evening 
and takes with it the threat for scattered light showers, there 
appears to be a large scale lack of lift forcing for a considerable 
period overnight, until late night when frontogenetic support from 
northern jet streak begins to encroach on the CWA. Additional threat 
for storms closer to the 925-850 hPa frontal boundary toward I-80 
earlier in the night is usually a strong signal to keep chances 
down, at least for a while and until more northern stream forcing 
moves into the region. 

Thunder threat remains generally focused with better elevated 
instability signals mainly south of a Pickstown to Spencer line 
where median instability may reach 200-400 J/kg. While there may be 
up to a couple hundred J/kg up toward I-90, signal is far from 
consistent the further north one progresses, and will keep thunder 
only in the far southern areas, to south of stronger frontogenetic 
banding. 

Still enough inconsistency in solutions to keep from hoisting 
widespread categorical pops for many area on Wednesday despite the 
strong frontogenetic forcing in well-defined jet entrance, 
especially with considerable north/south variations and complexity 
of the lower level dry air.  With the abundance of clouds and wet 
bulb process with rainfall, temps may not reach 60 degrees for some 
areas south of I-90, with warmest readings into the mid 60s along 
the far northern fringes around KHON/KMML.


.LONG TERM...(Wednesday night through Tuesday)
Issued at 327 PM CDT Tue May 9 2017

Relatively quiet pattern Thursday into the weekend as upper level 
low moves from the Central Plains into the mid-Mississippi Valley 
and upper level ridge builds into the Northern Plains.  Southerly 
winds are expected to increase through the weekend, and have raised 
winds and forecast highs both Saturday into Sunday.  

As southwest flow develops aloft early next week, could see a more 
unsettled pattern as a series of waves move from southwest to 
northeast. Cold front is expected to work through the area on 
Monday, but still some timing differences between the various 
solutions.  For now, left pops next Monday as is, with the highest 
pops through the overnight hours Monday night into Tuesday morning.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 101 PM CDT Tue May 9 2017

VFR conditions will accompany rainfall which will progress 
east/northeast across the area this afternoon and early evening, 
with generally VFR conditions accompanying the main precipitation
band expected to develop later tonight through midday Wednesday,
mainly near and south of Interstate 90. The exception will be for
ceilings to fall into the MVFR range south of I-90 during the
morning, as well as some brief periods of MVFR visibility.


&&

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

$$

SHORT TERM...Chapman
LONG TERM...BT
AVIATION...Chapman