Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 292327 AAA
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
627 PM CDT Thu Sep 29 2016

.SYNOPSIS...
Issued at 324 PM CDT Thu Sep 29 2016

H5 hand analysis this morning has an amplified pattern
across the CONUS. A cutoff low was located near Louisville KY with a
trough of low pressure extending south from the low into Florida. HT
rises of 70 to 80 meters were located to the north of the low while
some 60 meter ht falls were present on the srn periphery of this
feature. High pressure was located across the big bend of Texas with
a ridge extending nnewd into the eastern Dakotas and western
Minnesota. West of the ridge, a closed low was located off the west
central coast of British Columbia. A trough extended southwest from
the low into the eastern Pacific. South of this feature, a strong
shortwave was noted off the coast of northern Baja California.
Abundant mid and high level moisture in association with the wave
off the coast of Baja California, has pushed northeast into the swrn
CONUS this morning per WV imagery. So far, these clouds have
remained well southwest and west of the forecast area. At the
surface, high pressure was anchored over eastern Nebraska. West of
this feature, southerly winds on the back side of the high have
increased this afternoon and were blowing as high as 10 to 15 KTS
with an occasional gust to 20 KTS.

&&

.SHORT TERM...(This evening through Friday)
Issued at 324 PM CDT Thu Sep 29 2016

Tonight and Friday...Temperatures will be the main
forecast challenge in the near term. For tonight: The cutoff low
over the Ohio Valley will remain stationary over the next 36 to 48
hours. Surface high pressure on the western periphery of this closed
low will remain in place as well. Southerly winds will diminish
around sundown as we quickly decouple east of the panhandle. Under
clear skies and with light winds and dry air in place, lows will
bottom out in the 40s. Lower 40s are expected in the east and upper
40s are forecast in the far west, where southerly winds are not
expected to totally de-couple, and a decent pressure gradient will
remain in place tonight. As for the Platte River Valley, went ahead
and lowered min temps under guidance, as the trend for the min T
trend the last couple of nights has been cooler than guidance. Was
worried about the potential for fog as the NAM12 solution hits the
BL RH field pretty hard tonight in the far east and and eastern
panhandle portions of the forecast area. This notion has no support
form the MAV, GFS and SREF visby and low cloud ensembles. Since we
do not appear to be advecting any appreciable low level moisture
overnight, will leave out the mention of fog attm. For tomorrow:
High pressure will be anchored across the mid Missouri valley. Low
amplitude ridging will begin to weaken Friday, which will allow weak
southwesterly flow aloft to push into the Rockies. The result will
be a deepening surface trough of low pressure along the front ranges
of Colorado and Wyoming. With the surface trough in the west and
high pressure east of the area, the pressure gradient will steepen
across the western forecast area. This will lead to breezy
conditions Friday afternoon. With good mixing in the central and
western forecast area, forecasted highs above guidance for Friday.
This was more in line with forecast soundings Friday afternoon which
were indicative of mid 70s for highs, vs. the lower 70s as guidance
had.

.LONG TERM...(Friday night through Thursday)
Issued at 324 PM CDT Thu Sep 29 2016

A benign weather
pattern will continue through most of the weekend with seasonal
temperatures and dry conditions. There was a slight chance for
precipitation Saturday evening which was in the inherited grids.
This was taken out of the forecast as lift in the latest model runs
is very weak and moisture is confined to the mid and upper levels.
With dew points in the 40s Saturday, felt moisture was meager enough
to not warrant pops attm. Beyond Saturday night, the next threat for
precipitation will begin in the far northwest Sunday night,
transitioning east Monday night into Wednesday. This is in
association with a potent upper level low which will lift across the
western into the central CONUS next week. Both the ECMWF and GFS
solutions do have this closed low depicted in their model solutions
next week. However there are some differences in the track and
strength of the downstream ridge next week. The GFS solution takes
on a negative tilt for Wednesday, which would favor more wrap around
precipitation and a better threat for thunderstorms in the warm
sector for Tuesday. The ECMWF solution is more progressive initially
with the low not taking on a negative tilt until it reaches the
Dakotas on Thursday. With both solutions, the southwestern forecast
area has a good shot at getting dry slotted and pops were lowered
across the far southwestern CWA. Better chances for precipitation
will exist in the central and eastern forecast area where moisture
will be favorable for convection, and in the far northwest where
wrap around precipitation potential will be highest.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 627 PM CDT Thu Sep 29 2016

Low pressure will remain across the Nrn High Plains tonight and
Friday. Return moisture will be limited by dry air recycling north
from high pressure centered over Ontario and Quebec. This high
pressure is ridging south into the Srn Plains blocking moisture
return from the South. This will likely produce VFR conditions
for the next 24 hours.

&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC



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