Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 152032

Area Forecast Discussion
National Weather Service Aberdeen SD
332 PM CDT Fri Jun 15 2018

.SHORT TERM...(This Evening through Saturday Afternoon)
Issued at 332 PM CDT Fri Jun 15 2018

Late this afternoon, a surface frontal boundary was extending from
northeast SD and then southwest into central Nebraska. There was a
weak surface low pressure area on this boundary in northeast SD. The
issue tonight will be if the lift from a short wave trough moving in
from the southwest will be enough to overcome the warmer mid level
temperatures. Some of the models indicate this will occur with
showers and storms developing with good qpf like the gfs and hrrr
while the nam and rap13 showed little if any qpf. At any rate, there
will be plenty of instability and moisture available to the storms
if they can get going. Have in chance pops tonight/early Saturday
morning. Otherwise, there looks to be a break for Saturday morning
into the early afternoon for much of the cwa before another short
wave trough makes its way into the region for the late afternoon.
With surface heating and continued good instability, deep layer wind
shear, and cooler mid level temperatures, thunderstorms are expected
to develop. With precipitable waters getting up to close to 2 inches
with the help of the moisture from tropical system Bud, heavy
rainfall could occur with these storms.

.LONG TERM...(Saturday Evening through Friday)
Issued at 332 PM CDT Fri Jun 15 2018

The threat for heavy rainfall, as well as severe storms, Saturday
night through Sunday night will be the main concerns in the long
term. The period begins with an upper level ridge over the Ohio
Valley with southwesterly flow over this region. Remnants from
Hurricane Bud will likely bring record to near record PWATS,
especially 0Z Sunday. Both the NAM/GFS show PWATS of 1.90 inches,
which would rank in the top ten highest values for June. While not
outside the climatological mean, NAEFS return interval does indicate
the high PWATS occur once every 5 to 10 years. A possible rare
rainfall record is at stake. Remnants from Hurricane Lester in
August, 1992 produced 3.29 inches of rain in southeast SD. The 3.29
inches is the most SD has seen from a tropical cyclone since 1950.
It is possible this record could be broken Saturday through Sunday.

With a 40 to 50 knot LLJ, gradient of instability, severe storms
will be possible Saturday night into early Sunday morning.
Instability quickly wanes on Sunday with the severe threat best
south of this CWA. Conditions should dry out early next week before
pcpn chances move back into the region late next week.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1254 PM CDT Fri Jun 15 2018

VFR conditions are expected through tonight and Saturday morning for
all airports. Expect some VFR sct layer surface heating clouds
today. Otherwise, as an upper level low pressure trough moves in
from the southwest tonight, expect scattered showers and storms to
develop and may affect the airports at or in the vicinity into
Saturday morning.




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