Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 221139

Area Forecast Discussion
National Weather Service North Platte NE
539 AM CST Wed Nov 22 2017

.SHORT TERM...(Today and tonight)
Issued at 336 AM CST Wed Nov 22 2017

Warm air returns to the Plains today as the upper ridge anchored
near the Baja of Mexico ridges north and builds east across the
Intercontential Divide. Forecast challenge is temperatures as
readings will be some 20 degrees or more warmer than felt on Tuesday
in the west.

Overnight temperatures rose across western Nebraska as surface winds
shifted more westerly. That warming trend will continue today with
readings to reach into the low to middle 60s across the west by 3 pm
CT or 2 pm MT. How far east those warmer temperatures are felt is
the big question. For now the models are in good agreement with the
surface high centered over the east central Plains to move south and
east, while the next surface low pressure center develops east
across the northern Plains. As the low center and associated surface
trough moves east the warm air spreads east. The models show some
differences in how far east the surface trough will extend southwest
with a slight shift eastward could result in temperatures some five
degrees warmer in locations east of a line from Butte, Taylor and
Broken Bow this afternoon. For now the far eastern north central
counties (Boyd, Holt and Wheeler)are forecast to be cooler with
readings to trend down to near 50 east to include the Ewing and
Bartlett areas this afternoon. Otherwise, some high clouds today and
light winds.

Tonight dry, mild with lows dropping into the mid to upper 30s and
few clouds.

.LONG TERM...(Thursday through Tuesday)
Issued at 336 AM CST Wed Nov 22 2017

The dry northwest flow continues through at least early next week
with high pressure in the mid and upper levels anchored over the
southwest.  There is a sharp trough that does break down the ridge
early next week and may provide for some light precipitation across
northern portions of the CWA Tuesday.  Temperatures through the
extended look to remain largely above average and in some cases well
above average.

A sfc trough off the lee of the Rockies will provide for southwest
downsloping flow, this will result in highs in the upper 60s to
lower 70s across west central Nebraska.  Climatologically speaking,
highs in the upper 60s and lower 70s are some 20-25 degrees above
average for this time of year.  Record high temperature at North
Platte and Valentine for Thursday are 72 and 70 respectively, we are
forecasting 68.

Will be monitoring the progression of a strong clipper/cold front on
Friday.  CAA behind the front will cool temperatures slightly, 24
hour trend is down 5-10 degrees, but the main story will be the
windy conditions.  H85 winds late morning are advertised by the
various models to reach 40-50kts, mixing and the approaching surface
high will result in wind gusts in excess of 30 mph across west
central Nebraska.  The strongest momentum looks to be across north
central Nebraska where 40+ mph will be possible.  The system has
virtually no moisture to work with when atop the central plains, so
no needed moisture.  We will be monitoring  the grassland fire risk
with the front.  At this point, temperatures and dew points support
RH values in the upper 20s and lower 30s.  Also, we`re at about 9:50
of low angle sunlight and when considering the potential of mid or
high clouds, any substantial shading of the fuels will shut down
large fire spread potential, even with 30+ mph winds.  Will
continue to monitor, but no fire headlines are planned.

Temperatures rebound this weekend as the ridge remains to the west
and dry northwest flow continues.  The next lee trough develops and
provides for southwest downsloping flow on Sunday.  Temperatures
warm back to near 70 across southwest Neb, 60s elsewhere.  The
mid/upper ridge shifts east late weekend with the axis overhead
early Monday, another warm day is expected.

Models are advertising a pattern change to southwest flow early next
week with a trough and upper level jet digging across the west.
Another strong front is likely with gusty conditions possible early
Tuesday.  The models do show some light QPF for our northern zone
early Tuesday as well, but available moisture is less than ideal,
so confidence is not too high in anything more than sprinkles.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 537 AM CST Wed Nov 22 2017

Visual Flight Rules over western and north central Nebraska in the
next 24 hours. Models are in good agreement with some high level
cloudiness to spread downstream with light winds.

Issued at 336 AM CST Wed Nov 22 2017

A strong "cool" front is expected on Friday.  Behind the front
temperatures will cool some 5-10 degrees, but wind speeds will be
gusty.  Wind gusts in excess of 30 mph appear likely in open areas
with the potential of 40 mph across north central Nebraska.  Enough
cold air advection behind the front will help keep minimum relative
humidity values largely at 25% or higher.  A strong front with wind
is a watch out as fuels are fully cured, but with such a low sun
angle, some clouds expected, and non critical relative humidity, it
will be difficult to get those fuels to actively support extreme
fire growth.  We do not anticipate any fire headlines unless those
RH values trend noticeably drier.




LONG TERM...Jacobs
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