Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 180924

Area Forecast Discussion
National Weather Service North Platte NE
424 AM CDT Mon Oct 18 2021

.SHORT TERM...(Today through Tuesday)
Issued at 411 AM CDT Mon Oct 18 2021

Upper level ridging will gradually shift eastward today across the
Mississippi River Valley, meanwhile a potent shortwave trough will
be moving eastward from the west coast toward the Rockies. Flow
aloft across our region will become southwesterly ahead of this
feature. Expect some increase in high level cloudiness today as
upper level moisture begins to increase within the southwest flow.
Dry air in the lower levels remains in place and again have sided
with the warmer guidance for highs temperatures today. In fact,
highs have been averaging near the 90th percentile the last few
days. There could be some minor impact on temperatures from the
periods of Cirrus clouds expected to cross the area, and boundary
layer mixing is a little less compared to the last several days, but
still mid to upper 70s should be realized at most locations.

Surface cyclogenesis will be underway in the vicinity of southeast
Wyoming tonight as the shortwave trough begins to approach the area.
Low-level southerly flow will increase in response across the
Central and Southern plains. This will draw somewhat more moist air
northward into the region, with dew points rising into the lower 40s
across the southeast half of the forecast area overnight into
Tuesday morning. The increase in moisture will help keep lows warmer
than the past several days.

As the shortwave moves into Colorado and Wyoming Tuesday, a compact
closed circulation at H5 will be located near the Wyoming Colorado
border with the H7 low offset a bit to the east. Meanwhile the
surface low will begin to eject eastward into the Sandhills of
western Nebraska. Low-level warm moist conveyor will continue to
advect northward to the east of the surface low, and begins to
wrap back to the west into northwest Nebraska north of the surface
low by late Tuesday afternoon. A cold moist conveyor also
strengthens across South Dakota into northwest Nebraska as the
closed circulation moves into the Panhandle by late afternoon.
Isentropic upglide increases as this occurs and is maximized
Tuesday night across far northwest Nebraska into western South
Dakota. This coincides with a decent area of negative EPV and
supports the potential for heavy banded precipitation within the
deformation axis. The axis appears to be centered across Sheridan
into northwest Cherry county and on up into southwest South Dakota
immediately northwest of the closed mid level circulation that
will be moving into the Sandhills during this time. Sounding
profiles from this area indicate a mix of rain and snow mid
evening then changing to all snow late evening through the early
morning hours Wednesday. Confidence is increasing in some snow
accumulation potential and have increased amounts to around 2"
across northern Sheridan county especially in the Pine Ridge. Will
have to watch this closely and monitor trends for potential heavy
banded precipitation leading to more snow accumulation.

.LONG TERM...(Tuesday night through Sunday)
Issued at 411 AM CDT Mon Oct 18 2021

Wrap around lingering light rain or snow will continue Wednesday
morning across northern Nebraska as the system quickly moves east
into Iowa by Wednesday afternoon. Breezy to locally windy conditions
are expected though the day Wednesday. H85 wind speeds are 25-35 kts
on the backside of the system, and bufkit sounding data indicates
sustained speeds of 20-25 mph with gusts to around 35 mph are
likely. Otherwise a below normal temperature day with strong CAA.
Subtle upper level ridging across the Rockies late in the week will
amplify as it spreads eastward across the central CONUS during the
weekend. Near or slightly above normal temperatures will return as
this occurs.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1120 PM CDT Sun Oct 17 2021

VFR conditions expected to prevail through tomorrow night. Winds
will be gusty from the south tomorrow afternoon across central and
north central Nebraska, with gusts around 15 to 25kts anticipated.
Southwesterly LLWS will develop tomorrow night across south
central Nebraska, though is expected to remain southeast of KLBF.


Issued at 411 AM CDT Mon Oct 18 2021

Seasonably warm, dry, and breezy conditions continue today,
resulting in elevated to near critical fire weather across the
forecast area. The main concern in the panhandle and western
Sandhills revolves around very dry air with humidity values near or
below 20 percent. Across central Nebraska, generally east of Hwy 83,
wind is the main concern as southerly winds gust to 30 mph at times.
As of now, the overlap between the lowest humidity and strongest
winds appears large enough to preclude any serious concerns.
However, any first start may be capable of spreading rapidly,
especially east of Hwy 83.

A strong cold front passes through tomorrow, bringing rapidly
strengthening west/northwest winds regionwide through the day.
Significant moisture totals are possible for northwest Nebraska, but
enough dry air remains in southwest Nebraska to limit overall
precipitation potential. For areas south of I-80, humidity values
may be low enough to warrant another elevated to near critical fire
weather day.




LONG TERM...Taylor
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