Area Forecast Discussion


808 
FXUS65 KCYS 110003
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
503 PM MST Sun Dec 10 2017
.UPDATE...
Issued at 501 PM MST Sun Dec 10 2017
Reds Flag Warning for fire weather zones 312-313 in western Nebraska
Panhandle was allowed to expire at 5 PM this afternoon. Sustained
northwest winds have decreased to 10-15 mph with humidities expected
to slowly recover as temperatures cool after sunset.
&&
.SHORT TERM...(This evening through Monday)
Issued at 232 PM MST Sun Dec 10 2017
Tranquil weather prevails. A 1040-mb surface high remains over the
Intermountain West this afternoon, contributing to sunny skies and
dry conditions across the entire area. This is also resulting in a
fairly tight pressure gradient, so winds have been fairly gusty so
far today w/ critical to near critical fire weather conditions for
the western NE Panhandle. Inherited Red Flag Warnings have been on
the marginal side, with generally sporadic wind gusts in the range
of 25-30 MPH so far today. RHs are below 10 percent, however. 
Windy again on Monday w/a strong shortwave & associated cold front
progged to push across the Dakotas into Nebraska from late tonight
through Monday. The GFS shows a swath of H7-H8 flow between 50 and
60 knots along/east of a Lusk-Sidney line at 15z Monday, but flows
decrease markedly in the afternoon. A few gusts to 50-55 MPH could
occur, but do not think mixing will be deep enough to warrant high
wind headlines at this time. Concerning RFW conditions, RHs should
remain above the 15 percent threshold over western NE thanks to an
early arrival of the cold front. No precipitation is expected.
.LONG TERM...(Tuesday night through Saturday)
Issued at 247 AM MST Sun Dec 10 2017
Upstream ridge of high pressure will yield northwest flow through
the period. The result will be an above average week for
temperatures along with mainly dry conditions. After a very mild
day on Tuesday, a series of moisture-starved clipper systems will
dive into the northern high plains and upper midwest on Wednesday
and Thursday. The main story with these clippers will be the 
reinforcing shot of cooler (still above normal) temps Wednesday- 
Thursday. Highs will fall into the 40s to near 50 both days. Flow 
deamplifies a tad on Friday, as weak shortwave transitory ridge 
moves through. In addition, low-level gradients should begin to 
kick winds up close to high wind criteria across wind prone 
areas. Medium range guidance is consistent in driving another 
front thru the region Friday night. There may be a period of light
precipitation late Friday night/early Saturday morning, but 
latest models have trended drier. Temperatures will again cool 
slightly behind the front for Saturday. Long range outlook 
suggests another high wind event Sunday afternoon through Monday 
morning.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday afternoon)
Issued at 520 PM MST Sun Dec 10 2017
VFR. A weather disturbance aloft will progress southeastward from
eastern MT and western Dakotas tonight, heralded by a band of SCT to 
BKN cirrus clouds. Westerly surface winds 5-15 KT this evening will 
become northwesterly 15 KT with gusts to 25 KT late tonight east of 
the Laramie Range. Gusts of 25-40 KT are likely after 16Z Monday 
across the high plains.
&&
.FIRE WEATHER...
Issued at 247 AM MST Sun Dec 10 2017
Another critical fire weather day across the Nebraska Panhandle.
Will be a period late morning through mid afternoon where gusty
winds and low humidity combines to create critical fire weather 
conditions. A Red Flag Warning is in effect from 10 AM this 
morning through 5 PM this afternoon for FWZs 312 and 313. Winds 
picking up again Monday as a Clipper system tracks across central 
South Dakota and central Nebraska. Fortunately...humidity Monday 
afternoon is expected to be a little better than today. Windy 
conditions again Wednesday across the Panhandle as yet another 
Clipper system tracks across central Nebraska.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...MAJ
SHORT TERM...CLH
LONG TERM...CAH
AVIATION...MAJ
FIRE WEATHER...GCC