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Area forecast discussion 
National Weather Service North Platte NE
622 PM CDT sun Sep 21 2014

Synopsis...
issued at 308 PM CDT sun Sep 21 2014

At 500 mb ridge over the western Continental U.S. With cutoff low centered over
Nevada. Trough into eastern Continental U.S. With fairly strong wave moving
up eastern Seaboard.

&&

Short term...(this evening through monday)
issued at 308 PM CDT sun Sep 21 2014

Tonight and tomorrow. Cool surface high pressure will
continue to build southeast over the middle-Missouri Valley
overnight...allowing the lower tropospheric wind atop the County Warning Area to
veer to easterly and eventually south. The eastward advancing high
will also allow for the development of a High Plains low level jet
overnight...which will warm lows on Monday a few degrees across the
higher terrain of our west. At this time...the warmest overnight lows are
anticipated across southwest Nebraska where low 50s are forecast.
The coolest readings to remain over our east with lows in the lower
to middle 40 range for locations along and east of the Highway 83
corridor. These values are a result of a general blend of the
previous forecast with available British Columbia/regular numerical guidance and
nudged slightly from there. Monday...transitory shortwave ridge to
give way to a middle/upper level trough with the prospects of
precipitation late in the afternoon. Southerly return flow will
strengthen through the afternoon...with the subsequent increase in
lower level moisture. The shorter range deterministic continue to
forecast a general increase in precipitable waters with most locations above and inch
by middle afternoon. Large scale lift is anticipated to increase with
the approaching trough such that showers and storms are anticipated by
late afternoon across our western zones. The rain chances were
delayed as the models continue to indicate a slower arrival of the
moisture and lift. In addition to slowing the onset of
precipitation...decided to word thunder chances as isolated as bufr
soundings and the deterministic data reveals limited instability.
High temperatures Monday afternoon were nudged up slightly from the
numerical guidance as the onset of clouds and quantitative precipitation forecast will be delayed
somewhat.

Long term...(monday night through sunday)
issued at 308 PM CDT sun Sep 21 2014

Models backing off some with timing and precipitation amounts.
Will generally follow previous forecast as far as timing and
duration. In the middle term upper closed low over northern Wyoming
Monday evening with good height falls ahead of the system. Ongoing
afternoon convection over the Panhandle and far western Nebraska.
30-40kt low level jet across southwest Nebraska into the sandhills
will enhance and expand convection. Surface high to the east with
western Nebraska in the return upglide flow will help to further
enhance lift. Strong moisture advection with southerly flow dew points
increase from 40s into upper 50s with precipitable waters from 0.8 Monday
afternoon through 1.3 Tuesday morning...a couple of Standard
deviations above normal. Lows in the 50s. The upper low will move
east into southwest South Dakota and northwest Nebraska Tuesday
morning with the initial wave and convection shifting east. Second
wave to drive through the bottom of the trough into western
Nebraska Tuesday afternoon with convection firing to the west and
then moving east over night with precipitation ending over the
east on Wednesday as the upper low shears northeast across the
ridge to the east. Highs in the 70s Tuesday with cloud cover and
precipitation and in the 70s and 80s Wednesday as the ridge builds in
behind the upper low and skies continue to clear. An upper trough
approaches from the west Saturday and Sunday with precipitation
spreading east into western Nebraska.

&&

Aviation...(for the 00z tafs through 00z Monday evening)
issued at 620 PM CDT sun Sep 21 2014

Increasing middle clouds on western and southwest Nebraska will
bring ceilings to the area...though they are expected to be at or
above 7000 feet above ground level. Wind is the main challenge to flight
operations after 15z Monday as they become 160-180 at
14-17g24-26kt. Toward late afternoon...ceilings will begin to
lower but they will still be above 3000 feet above ground level.

&&

Lbf watches/warnings/advisories...
none.
&&

$$

Synopsis...power
short term...Jacobs
long term...power
aviation...Springer

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