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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
1140 am MDT sun may 24 2015

Update...
issued at 950 am MDT sun may 24 2015

Regional radar mosaic shows a broad band of rain arcing from
north central Nebraska...across the Black Hills and into central
Wyoming. Upslope enhancement is producing the highest rain totals
over southwestern South Dakota and along the eastern slopes of the
Black Hills. The rain band is expected to push farther northward
as the day progresses. The widespread rain is ending over far
southwestern South Dakota at this time and it looks like the
widespread rain will end from south to north over the Black Hills
between 100 PM MDT and 400 PM MDT. Even after the widespread rain
ends...scattered showers are still expected through the afternoon
and into the evening. More widespread rain may develop over the
Black Hills area again on Monday.

&&

Short term...today through Monday night
issued at 300 am MDT sun may 24 2015

Water vapor shows large complex upper trough over the western Continental U.S. With
abundant moisture transport through the plains. An upper low was
noted over eastern Utah/western Colorado with jet streak lifting northward through far
eastern Colorado. At the surface...low was deepening over far northern Colorado/southeastern Wyoming.

Today...jet streak will nose into western South Dakota this morning with rain
becoming more widespread and heavier from northestern Wyoming through southwestern South Dakota.
This band of heavier precipitation will slowly lift northward through the
day...heaviest across our western two/thirds zones. Deep convection
will be limited today due to abundant low cloud cover...but if any
clearing takes place in our far southern zones near the Nebraska border a
few stronger storms could develop in the afternoon hours. In
general...expecting 0.50-0.75 inches in northestern Wyoming and western South Dakota...and
around 0.25 in our eastern zones today.

Tonight...better chances for widespread precipitation in our northern zones tonight
as upper low shifts into eastern Wyoming/western South Dakota...with some dry slotting
limiting precipitation somewhat in our southern zones.

Monday...upper low/trough slowly shifts into the eastern Dakotas with precipitation
chances gradually ending from west to east by Monday night.
Chances for deep convection on Monday again look rather slim given
expected widespread low clouds across the County warning forecast area.

Long term...Tuesday through Saturday
issued at 300 am MDT sun may 24 2015

Upper level flow will be from the west to southwest for
the upcoming week. This will keep the active weather pattern in
place...with daily chances for showers and thunderstorms. The better
chances for rainfall at this point looks to be Wednesday through
Friday...with some stronger thunderstorms possible during that time.
Temperatures will return to near average levels in most areas for
Tuesday through the rest of the week.

&&

Aviation...for the 18z tafs through 18z Monday
issued at 1128 am MDT sun may 24 2015

Widespread IFR ceilings with area of rain over much of southwestern South Dakota into
northestern Wyoming will continue through Monday morning. Upslope easterly flow is producing LIFR
ceilings over the Black Hills. Gradual improvement in conditions as
inverted surface trough moves into eastern NE-Dakotas and winds shift from NE
to northwest.

&&

Hydrology...
issued at 300 am MDT sun may 24 2015

Large band of rain is producing rainfall rates of 0.1-0.3 inches
per hour. Streams across the Black Hills are rising...with a few
locations above flood stage. Another inch of precipitation...with
localized heavier amounts...are possible. Rivers and creeks are
running high from the recent storms... especially across the Black
Hills and southwestern South Dakota. This additional rainfall may
cause more flooding.

&&

Unr watches/warnings/advisories...
South Dakota...Flood Watch through Monday afternoon for sdz024>031-041-042-
072>074.

Wyoming...Flood Watch through Monday afternoon for wyz055-057.

&&

$$

Update...10
short term...Johnson
long term...15
aviation...55
hydrology...55

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