Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 170547

Area Forecast Discussion
National Weather Service North Platte NE
1247 AM CDT Tue May 17 2022

Issued at 327 PM CDT Mon May 16 2022

H5 analysis this morning had a trough of low pressure which
extended form Hudson Bay south into the mid Ohio Valley.
Northwesterly flow extended to the Rockies, where a ridge extended
from Colorado, north into the Canadian Prairie. West of the
ridge, closed low pressure was located over the Gulf of Alaska
with a trough extending south into the eastern Pacific. Within the
ridge, shortwaves were noted over the Four Corners and over
northwestern Wyoming. At the surface, high pressure was anchored
over eastern Kansas into the Ozarks. Southerly winds had increased
this afternoon on the western periphery of the exiting high. Wind
gusts as of 3 PM CT were as high as 41 MPH at Imperial. Under
mostly clear skies temperatures ranged from 79 degrees at O`Neill,
Ainsworth, and Gordon to 87 degrees at Imperial.


.SHORT TERM...(This evening through Tuesday night)
Issued at 327 PM CDT Mon May 16 2022

The main forecast challenge in the near term is thunderstorm
chances and severe potential tonight and Tuesday night. The latest
CAMS suggest storm initiation over the higher terrain of the
Cheyenne late this afternoon. This activity will ride to the east
southeast, where it will approach southwestern Nebraska around 7-9
pm CT. As for severe mode, forecast soundings indicate an
inverted V type with strong to severe thunderstorm wind gusts
being the main threat. Additional support for gusty winds is
indicated in the latest NAM 12 DCAPE forecast which has forecast
DCAPE of 1500 to 1800 J/KG from southwestern Nebraska into the
panhandle at 00z Tuesday. As for storm coverage, meager low level
moisture would suggest isolated coverage of storms this evening.
That being said, will limit pops to the 20 to 30 percent range
this evening. Later this evening as convection crosses the highway
83 corridor, it will encounter a nice low level jet. The nose of
this will be focused over northern Nebraska into South Dakota.
Wouldn`t be surprised if we see some convective development late
tonight in the eastern and northeastern forecast area INVOF this
feature. Inherited forecast had a mention of low pops overnight
and see no reason to remove this ATTM. As for the severe threat
overnight, the threat will decrease markedly after midnight and
further east as deep layer shear falls off to around 20 KTS toward
12z Tuesday. The precipitation forecast for Tuesday
afternoon/night becomes more murky as forecast confidence wanes
significantly with this morning`s runs. A surface frontal boundary
is forecast to stall out from NW Kansas into NE Nebraska on
Tuesday afternoon. The surface boundary should be the focus for
convective development tomorrow afternoon. The latest ECMWF buys
into convective development along the boundary tomorrow afternoon,
while the NAM12, WARW and GFS solns limit convective initiation
to later on over the higher terrain off to the west. This is
problematic and once again will limit pops to slight chances as
location and timing of initiation remain problematic with this
forecast. As for severe mode, the best chances will be INVOF the
surface frontal boundary. Mid level lapse rates are favorable for
large hail in the southwestern forecast area while DCAPES and
forecast soundings, indicate a more limited threat for severe
winds (with respect to what is expected this afternoon and
evening). As for the tornado threat, low level winds are fairly
weak tomorrow and low level helicities are not overly supportive
of a tornado threat in our forecast area. The tornado threat,
albeit minor, appears to be east of the forecast area over eastern
Nebraska. Finally, there is some disagreement as to the
sustainability of convection into the overnight, especially over
SW Nebraska. I went ahead and introduced some low end pops in SW
Nebraska for late Tuesday night. This was more on a hedge to the
NAM12 and WARW solns which did force some storms into far srn
portions of the forecast area overnight. This was largely void in
the EC and GFS solns.

.LONG TERM...(Wednesday through Monday)
Issued at 327 PM CDT Mon May 16 2022

After a fairly quiet Wednesday with highs in the upper 70s to
lower 80s, a strong cold front will approach the forecast area on
Thursday. In advance of the cold front, an inverted trough of low
pressure, will become oriented from SW Nebraska into portions of
north central Nebraska Thursday afternoon. INVOF this feature,
winds will be fairly light, which in light of the expected low RH,
will limit fire weather concerns Thursday. That being said, with
forecast dew points in the 30s and H85 temps in the upper 20s to
lower 30sC highs will reach into the upper 80s to around 90 across
southwestern into central Nebraska. With respect to precipitation
chances along the front the strongest forcing aloft will be
across northeastern Nebraska. That being said, pops will be
limited to post frontal activity Thursday night. Much cooler air
will push into the region on Friday. Cloud cover should keep
Friday mornings temps somewhat "elevated" in the 40s. However,
with clearing skies over northern Nebraska Friday night, locations
in northwestern and western Nebraska have a decent threat for
frost and even freezing temperatures Saturday morning. The latest
NBM has a high probability >70 percent of < 35 degree temperatures
Saturday morning west of highway 61 and north of I80. Will
continue to hammer this in the HWO and have inserted frost and
freeze wording in the grids for Saturday morning. Temps will be
chilly once again on Sunday morning, however surface high pressure
will be east of the forecast area so slightly warmer readings are
expected. We still could see some frost in the NW CWA Sunday
morning, but forecast confidence is lower compared to Saturday.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1243 AM CDT Tue May 17 2022

VFR conditions are expected through the forecast period. Aviation
concerns focus on ongoing convection near LBF and points east with
additional convection possible later in the period. Ongoing
activity affecting LBF will be quick to depart in the period
returning the terminal to high-end VFR conditions. LLWS at VTN
will last until around sunrise before conditions improve. Watching
the potential for isolated to scattered thunderstorms developing
near a surface boundary with some uncertainty regarding precise
location. At this time, confidence is low in direct impacts at LBF
with favored location of this boundary stretching nearer a MCK to
LXN to ONL line and thus south of the terminal. This should be
considered medium confidence at best and adjustments in later
forecasts may be necessary.




SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...NMJ is the U.S. government's official web portal to all federal, state and local government web resources and services.