Scientific Forecaster Discussion
fxus63 klbf 222103
Area forecast discussion
National Weather Service North Platte NE
403 PM CDT Tue Oct 22 2019
Short term...(this evening through Wednesday night)
issued at 325 PM CDT Tue Oct 22 2019
Impacts/highlights and confidence: low-moderate confidence in
chances for precip, generally light rain-sprinkles, across
sandhills and northern Nebraska towards south central Nebraska tonight.
Additional chances late tomorrow-early tomorrow night. Moderate-
high confidence for breezy conditions tomorrow with peak gusts as
high as 40 mph, highest gusts across the eastern Panhandle and
Discussion: latest satellite imagery shows cu outside the eastern
Panhandle and extreme western Nebraska with more stratocu across the
Panhandle and greater sky cover upstream associated with the next
impulse. Latest water vapor imagery shows a weak short wave
trough moving into northeast WY, however, a bigger disturbance
upstream is entering the northern High Plains/western Montana. These
disturbances will track southeastward over the next 24 hrs in the
northwest flow and prompt low-end chances across northern Nebraska and
parts of the sandhills tonight and late tomorrow. Meanwhile, a
weak cold front will move through the area tonight. Breezy Post-
frontal winds are expected tomorrow given mean mixed-layer winds
per BUFKIT soundings showing potential for peak gusts up to 35 kts
that could be realized given upper-level winds to mix
Long term...(thursday through tuesday)
issued at 325 PM CDT Tue Oct 22 2019
Impacts/highlights and confidence: fair and dry weather through
Saturday with a warming trend Friday-Saturday with highs peaking
Saturday about 5-10 degrees above seasonable values. There will be
heightened fire weather concerns attributable to low afternoon
humidity across the southeast Panhandle and southwestern neb,
however, winds could be a limiting factor. That said, a cold front
is expected Saturday that will provide breezy winds and a wind
shift thus will continue to monitor the situation. Thereafter,
cold conditions for the season are expected Sunday-Tuesday with
highs Monday and Tuesday forecast to be 15-25 degrees below
seasonable normals. Wind chills less than 10 above are possible
towards mid next week, below climo for this time of year, per CPC
guidance. Confidence, moderate presently, is growing in colder
than normal temperatures Sunday and beyond.
Discussion: large scale pattern early Thursday will be
characterized by cyclonic flow affecting the central and eastern
Continental U.S. With an amplified positive tilted trough over the central
Continental U.S. And a basal shortwave trough over southern Colorado/northern nm.
Meanwhile, a mid-level ridge will be off the West Coast. This
ridge will build east out of the eastern North Pacific Thursday
with mid- level height rises spreading across the area Friday as
the ridge then extends from California across the northern plains.
Meanwhile, the aforementioned shortwave trough will track east
into the Southern Plains by late Thursday night/early Friday.
Although there is some uncertainty with guidance in whether it
becomes a closed low or stays as an open wave as the positive pv
anomaly crosses the Southern Plains and into the lower Mississippi
Valley Friday- Saturday. Meantime, broad surface high pressure
will be in place across the Central Plains Thursday. Under
northwest flow aloft cold air in place will be supported another
day Thursday. High pressure thereafter evolves southward into the
Southern Plains and lower Missouri Valley by Friday.
The ridge will then breakdown Friday night-Saturday with a cold
front associated with the next upper trough expected to advance
across the area Saturday. This will promote unsettled conditions
with chances for precipitation generally Sunday-Monday night.
Meanwhile, ensemble forecast systems all support much cooler air
impacting the region. Starting Sunday, both naefs and European model (ecmwf)
ensemble forecast systems show colder than normal air
overspreading the western and central Nebraska. While anomalies are not
appreciable large, both naefs and European model (ecmwf) mean 700 and 850 hpa
temperatures are reaching the 2.5th and 10th percentiles,
respectively with coldest temperatures expected on Monday-Tuesday.
This seems reasonable given the large scale pattern in this time
and the anticipated reinforcing shots of cold air as upper
troughing prevails Sunday-Tuesday.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1235 PM CDT Tue Oct 22 2019
Main aviation concerns will be the development of low level wind shear up to 45kt
09z-14z Wednesday, to mainly affect the kvtn terminal. Stronger
winds off the surface will move into western Nebraska late tonight
as a cold front move in. At the surface, northwest winds will peak near
32019g32kt at kvtn near the end of the taf period.