Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 171145
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
645 AM CDT Wed May 17 2017

.SYNOPSIS...
Issued at 328 AM CDT Wed May 17 2017

H5 analysis from earlier this evening had a closed low
over southern Colorado with a couple of lead shortwaves noted in
northwestern Kansas and the Nebraska panhandle. Up stream of this
feature, closed low pressure was noted over central Washington,
while a ridge extended downstream of the central plains and was
located from the sern states into Michigan. Overnight, the low over
southern Colorado had moved east northeast into east central
Colorado. Showers and thunderstorms from earlier this evening had
begun to wind down across southwestern Nebraska and as of 3 AM CDT
were located mainly over north central into eastern Nebraska.
Additional activity was located over eastern Colorado on the western
periphery of the upper level low. Under mostly cloudy skies
overnight, readings were in middle 50s.

&&

.SHORT TERM...(Today and tonight)
Issued at 328 AM CDT Wed May 17 2017

Today and Tonight...Over the next 24 hours,
precipitation chances are the main forecast concern. For today:
Upper level low pressure will track from western Kansas into far
eastern Nebraska. After a brief reprieve in precipitation, early
this morning, showers will develop once again across the forecast
area. Isentropic lift will increase on the northern and western
periphery of the low this morning across western and central
portions of the forecast area, and will transition east later this
afternoon into the early evening hours. Will continue to mention
thunder today in the weather grids as surface based and elevated
instability remains across the forecast area with negative LI`s
noted. Light precipitation will continue to wrap around the upper
level low into northeastern portions of the forecast area this
evening. This activity will push east of the area by late evening
with dry conditions expected overnight. Further west, precipitation
chances will continue to increase across the eastern panhandle and
western sandhills overnight. Increased lift will push into the area
from the west in advance of the next upper level low. This feature
is expected to reside over northern Utah by 12z Thursday.

.LONG TERM...(Thursday through Tuesday)
Issued at 328 AM CDT Wed May 17 2017

Upper level low centered near the four corners will lift northeast
and swing a trough across the plains on Thursday.  In advance of the
system, transitory shortwave ridging with strong southerly flow will
help force a warm front north across Kansas.  Severe convection is
expected across the southern plains along the warm front and a sharp
dryline over the western high plains.  The Kansas convection will
lift north late afternoon and evening as additional storms develop
across western Nebraska with the approach of the upper low.  The cwa
will be in the cool section with limited instability, thus
widespread severe convection is not anticipated, but elevated
convection with heavy rainfall is most certainly possible.  The
shortwave trough/low takes on a negative tilt and lingers over
eastern Colorado through Friday and into Saturday setting the stage
for easterly upslope and a prolonged period of precipitation for
west central Nebraska. Enough cool air is drawn into the system to
promote a rain/snow mix or a complete change over to snow across our
far northwestern zones Friday evening and early Saturday.  The GFS
is the most progressive in ejecting the system to the northeast with
the other guidance and most ensembles slower. Will keep a mention of
qpf within the CWA through at least 00z Sunday to account for the
slower solutions. Cool temperatures are in store for Saturday and
Sunday as the system lifts leaving northwest flow aloft.  Frost is
possible Saturday morning over northwest Nebraska.

Additional precipitation chances arrive early next week with a
shortwave trough arriving down from the Canadian Rockies.  The
models are not in the best agreement with the early week system, so
will keep qpf potential at chance or less. The northerly flow will
keep temperatures seasonal or below average through the extended.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 645 AM CDT Wed May 17 2017

For the KLBF terminal: Expect MVFR CIGS through mid afternoon with
a threat for rain showers through 19z. Visibilities may fall as
low as 4sm with any moderate showers. After 22z, expect broken
cigs around 6000 ft agl to persist through the overnight with MVFR
cigs developing after 10z Thursday. For the KVTN terminal: MVFR
cigs are expected over the next 24 hours with a threat for rain
through 21z this afternoon. Visbys may fall as low as 4sm with any
moderate showers. The threat for rain will end after 21z with
overcast cigs around 1500 ft agl expected through 12z Thursday.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Jacobs
AVIATION...Buttler



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