Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 291722
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1222 PM CDT MON AUG 29 2016

.SHORT TERM...(Today and tonight)
Issued at 355 AM CDT Mon Aug 29 2016

The main concerns in the short term period are rain showers and
thunderstorms, and possible locally heavy rainfall. Otherwise, no
severe thunderstorms with respect to winds or hail are expected
this period. A cooler day will prevail compared to yesterday
across western and north central NE. High temperatures today will
range from near their seasonal normal values along and south of
Interstate 80 (low to mid 80s) to readings 5 to 8 degrees above
normal across portions of the northern-third of the forecast area
(upper 80s). This will be attributable in part to increasing
cloudiness across central NE while a bit more insolation is
expected across parts of western NE and far north central NE with
less cloud cover. Lows overnight will be warmer than normal with
upper 50s to lower 60s expected.

Weak to neutral height rises will persist over western and north
central NE today with little change in the overall mid-level
pattern. A broad 500 hPa ridge positioned across the lower/middle
Mississippi Valley from the Middle Atlantic extends into the
central Plains while ridging persists across California into the
Central Great Basin/Intermountain West; meanwhile, a upper low
that`s currently near the southern Rockies/four corners region
will be filling in and weakening today. While there will be weak
large scale ascent associated with a disturbance moving northward
into the forecast area associated with the aforementioned low,
it`s difficult to place finer details in terms of coverage. This
is largely attributable to this complicated pattern. Models are
having a difficult time with precipitation when comparing
guidance QPF and their placement. Models suggest increased chances
and increased coverage of thunderstorms/rain showers beginning
mainly in the afternoon through tonight, with the best chances
across the southeast-third of the forecast area.

Current thinking is convection will be largely unorganized to
weak multi-cell organization given the vertical wind shear,
generally around 15 kts at best, that then diminishes some in the
evening/early tonight. Current thinking remains that the main
concern would be local brief heavy rain. Today, central NE will
have precipitable water values approaching 1.4-1.5 inches, though
the NAM has a bit more moist of a column compared to the GFS
across north central NE. The former brings PW 150% of normal into
much of the forecast area this evening. Of note, the 00Z sounding
at North Platte and Omaha had 0.9 and 1.63 of precipitable
water, respectively. It is expected with decent moisture
transport that more of this moist air will push west into the
forecast area today. This combined with favorable anticipated
storm motion, generally about 5 kts or less, and thermodynamic
profiles suggest decent rainfall potential. However, in general,
a flash flooding threat is not expected given the flash flood
guidance and anticipated coverage but will continue to monitor.

.LONG TERM...(Tuesday through Sunday)
Issued at 355 AM CDT Mon Aug 29 2016

Models continue to struggle with the plume of moisture and
location of showers and thunderstorms for mid week across the
CWA. There is good agreement for areas of western Kansas into S
central Nebraska to see a chance for showers, however we are on
the NW side of the activity. This NW extent of the activity
varies between the differing models and a blend gives me a good
starting point to a low confidence forecast for precipitation.
Models show plenty of moisture just to the SE with pwats of over
1.5 inches which tapers to less than 1 inch across NW Nebraska.
Some concern for slow movement of storms and locally moderate to
heavy rainfall in the far SE. Recently the area has been dry with
the exception to ongoing rain over central Frontier county so
ground should be able to absorb a decent amount with low threat
for flooding at this time. As for temperatures the clouds will
put a damper on things despite decent thickness due to a broad
ridge across the southern CONUS. Forecast highs are actually
close to seasonal averages in the upper 70s to lower 80s. Lows
however will be on the mild side thanks to high dew pts. This
will also play a concern for possible fog. A few MOS guidance
points suggests fog with shref probs generally only 30 percent of
lower than 1 mile. Will include patchy fog, although some concern
the clouds/showers may limit development in the east to more
stratus than fog.

Trough digs across the west over the latter part of the week with
a upper low to slide across southern canada for the weekend as
ridge gets pushed/amplifies to the east. Southwest flow develops
and moisture increases through the column across the entire CWA.
This will result in pops across the area for the weekend, however
not looking to be wash but this far out tough to time subtle
waves. Temps dependent on cloud cover but generally seasonal
highs and mild lows continue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1222 PM CDT Mon Aug 29 2016

A disturbance moving northeast across the central plains will
spark off additional showers and thunderstorms across southwest
Nebraska this afternoon/evening. None of the storms are expected
to be severe, but the available guidance suggests some heavy rain
potential, leading to reduced visibility. The guidance holds the
majority of the rain south and east of the klbf, but close enough
to the terminal for at least a 30% mention in the forecast.
Otherwise there`s a fog signal setting up late tonight and early
tomorrow. At this point, mvfr ceiling and visibility looks
possible at klbf and other southwest Nebraska terminals.

&&

.LBF Watches/Warnings/Advisories...
None.
&&

$$

SHORT TERM...ET
LONG TERM...Masek
AVIATION...Jacobs



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