Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | 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

138
FXUS63 KUNR 242021
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
221 PM MDT SUN JUL 24 2016

.SHORT TERM...(This Evening Through Monday Night)
Issued at 209 PM MDT Sun Jul 24 2016

Current surface map places high pressure across the western
Dakotas. Isolated showers and thunderstorms decreasing in coverage
this afternoon as shortwave moves into central South Dakota. May
see something redevelop over the Black Hills through the remainder
of the afternoon. Otherwise, dry tonight with clear skies.

On Monday, high pressure slides east with return flow across the
forecast area. Increase in low level moisture through the day,
resulting in around CAPE around 2000 J/kg late afternoon into the
evening. Best chance of storms will be over the Black Hills in the
afternoon. Sufficient shear for a few supercells. Very slow storm
motion for supercells, so locally heavy rain is possible. Storms
will shift east Monday evening into the overnight hours as low
level jet increases east of the Black Hills.

.LONG TERM...(Tuesday Through Sunday)
Issued at 209 PM MDT Sun Jul 24 2016

Main fcst challenge for the extended once again deals with pcpn
chances through the extended. The extended starts off with a
slightly amplified zonal flow with a building west coast 500hpa
ridge with a deepening east coast 500hpa trof. The flow aloft
becomes more nw by the end of the extended...resulting in a drier
but warmer flow.

As for the pcpn...their is potential for stronger tsra and hvy rain
tuesday and wednesday...but difficulties still remain on exactly
where convection will fire across the west. Feel that Tuesday
morning will be a "reset the mechanism" type period with overnight
convection moving east...resulting in post tsra stable atmos. Also
noticed that models are in decent agreement on showing 850hpa and
700hpa theta-e downglide during the 12z-18z time period which should
also work to keep any tsra from firing. have pushed off pops for
much of the western cwa Tuesday until the aftn period when better
moisture and forcing returns. by 00z Wednesday pwats across parts of
wrn SD climb over 1.50"...with 850hpa-700hpa spec humidities 8+ g/kg
which should set the stage for potential heavy rain. Wednesday isn`t
as moist...but still can`t rule it out. Unsettled pattern pretty
much remains in place until Saturday when building wrn CONUS trof
finally begins to nudge back into the region helping to dry things
out.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 209 PM MDT Sun Jul 24 2016

Scattered showers and thunderstorms will continue
through the afternoon before dissipating by early evening. Expect
VFR cigs/vis through the period.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...7
LONG TERM...Hintz
AVIATION...Hintz



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