Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 180446 AAB
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1146 PM CDT Sun Sep 17 2017

.SYNOPSIS...
Issued at 350 PM CDT Sun Sep 17 2017

The H5 pattern this morning was highlighted by closed
low pressure over southern Manitoba and another closed low in the
Gulf of Alaska. A broad trough of low pressure was present across
the western CONUS which extended from Idaho south into the
California desert. Further east, high pressure was anchored over the
Gulf of Mexico with a ridge extending north into the Ohio Valley.
Further east, Jose was present off the coast of the Carolinas. Over
the central CONUS, broad west southwesterly flow aloft extended from
southern Nevada into Nebraska and southern South Dakota. Current WV
imagery has a nice tap of Pacific moisture extending from Baja
California through Texas into the Ozarks and western Great Lakes.
Further west, another area of Pacific moisture extended from southern
California into the central and northern Rockies. Within this area
of moisture, a couple of disturbances were noted today. The first
was located over south central Colorado, and a second over western
into northern Wyoming. At the surface, Low pressure was located over
Lake Superior with a cold front extending south, then southwest
across Missouri into the Texas panhandle. the front then turned west
into northeastern New Mexico and north along the front range of
Colorado. A weak upper level disturbance had spread isolated showers
to the sandhills this afternoon, the bulk of which wasn`t hitting
the ground thanks to a dry layer below 12000 FT AGL. Under partly
sunny skies this afternoon, temperatures were in the 60s.

&&

.SHORT TERM...(This evening through Monday)
Issued at 350 PM CDT Sun Sep 17 2017

Tonight and Monday: Over the next 24 hours
precipitation chances mainly tonight is the main forecast concern.
For tonight: A tandem of disturbances will approach western and
north central Nebraska this evening from the west. The first
disturbance will track into northwestern Nebraska and South Dakota
from northern Wyoming. The second disturbance will lift from eastern
Colorado into northwestern Kansas and southern Nebraska. Both
disturbances will be favorable for precipitation tonight across the
forecast area. The tricky part of the forecast lies with
precipitation chances. For precipitation associated with the
northern disturbance, cross sections indicate a fairly dry layer
below 10000 FT AGL this evening which will favor fairly low pops.
Also, current WV imagery seems drier with the streak of mid level
moisture tracking across the central Rockies from California. The
srn stream of Pacific moisture from Baja California, is much more
robust than the northern stream...more on this below. Further south,
the southern disturbance will track into southwestern, then central
and eastern Nebraska overnight. Cross sections taken through the
eastern and southern portion of the forecast area, indicate decent
moisture below 10000 FT AGL. This is co-located with strong low and
mid level lift tonight. With this in mind, will increase pops in the
30 to 40 percent range tonight. Low level instability remains weak
tonight, however elevated instability is decent tonight, so will
leave in a mention of thunderstorms vs. showers. Precipitation will
exit the forecast area on Monday with dry and warmer conditions
expected. Highs will be in the mid 70s in the east to the lower 80s
in the west.

.LONG TERM...(Monday night through Sunday)
Issued at 350 PM CDT Sun Sep 17 2017

An active week ahead as a large upper level trough digs south
through the western portions of the United states. Our region will
remain on the eastern periphery of the upper trough with southwest
flow aloft to dominate for the first half of the week, then a more
south-southwest flow aloft for the second half of the week as the
trough digs farther south into the southwest U.S.

The next chance for rain after tonight enters the picture late
Tuesday afternoon and Tuesday night. This looks most likely to
remain north in the Dakotas, but northern Nebraska will be in close
enough proximity to the upper wave moving across the Dakotas to
continue at least a slight or low chance for thunderstorms. SPC
continues to highlight eastern portions of north central Nebraska
for potential severe during this time. Moisture, instability and
shear look decent, and agree some stronger storms are possible along
the cold front Tuesday night.

The cold front will scour out the moisture for Wednesday through
Thursday night and expect dry conditions during this time. For
Friday into the weekend, rain/thunder chances will increase, as both
quality low level moisture and upper level dynamics become favorable
for precipitation development. Certainly could be some stronger
storms as dew points rise into the 60s and south-southwest flow
aloft increases as the upper trough approaches from the west.

A warm week ahead, with highs ranging from the mid 70s to mid 80s.
May even see upper 80s on both Tuesday and again Thursday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1143 PM CDT Sun Sep 17 2017

Tunderstorms will continue to move outh of the Nebraska Panhandle
into western Nebraska and others will move into south central
Nebraska through the early morning hours. Thunderstorm activity
will become more organized as they move east through the early
morning hours. Some stratus with mvfr cigs will continue between
KOGA and KLBF. Cigs may briefly lower into ifr categories around
sunrise. Skies will clear through the morning with southeast winds
over western Nebraska.


&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Taylor
AVIATION...Power


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