Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 190504
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1103 PM MDT Sat Mar 18 2017

.SHORT TERM...(This evening through Monday Night)
Issued at 216 PM MDT Sat Mar 18 2017

Very warm afternoon for mid March with widespread temps in the 70s
to the east of the Laramie Range.  Upper ridge axis is right
overhead currently and is progged to move eastward into Nebraska
overnight.  With deep mixed layer, starting to see some gusts to 20-
30 mph across the southeast WY plains over the past hour. However,
with marginal winds across most sites of FWZ 310 and winds aloft not
increasing through the remainder of the aftn, will hold off issuing
a Red Flag Warning.  Still thinking it is more of an elevated to
near critical fire weather threat.  It will continue to be breezy
along and west of the Laramie Range through sunset.

Ridge aloft will flatten on Sunday with increasingly zonal flow.
Similar to today, went lower than guidance on dewpoints with
downslope llvl flow and deep mixing of dry air aloft.  With
widespread gusts to 25-35 mph and min RH values falling to around 15
percent, the Red Flag Warning for Sunday looks good.  Another weak
front will back into the western Nebraska Panhandle on Sunday night,
hanging up along the WY-NE border by Monday morning.  Highs on
Monday will be 20-25 degrees cooler across the eastern zones behind
the front.  Kept widespread 20-50 percent Pops on late Monday into
Monday night with isentropic lift ahead of a weak upper wave.

.LONG TERM...(Tuesday through Saturday)
Issued at 216 PM MDT Sat Mar 18 2017

A more active period is setting up next week into the late next
weekend. The main questions will be timing of these waves
through, and precipitation type.

Tuesday-Wednesday:
Weak upper level ridging is expected to dominate the area through
early Wednesday which will tend to keep the bulk of the colder
air bottled up in the northern Plains. However, some of this
cooler air may try to spill into the northern Panhandle on
Tuesday morning as a back door cold front moves into that area.
Otherwise, return flow will setup over the area and bring rather
mild temperatures for this time of year with afternoon highs
generally in the 50s and 60s except for the northern Nebraska
panhandle where they will struggle to get out of the 40s on
Tuesday.

Wednesday night-Saturday:
A fairly potent, negatively tilted shortwave is progged to push
through the central Rockies and shift into the plains on Thursday
night and Friday. This system appears as if will undergo
cyclogenesis as it approaches the lee side of the Rockies on
Thursday. As this wave passes through, we are looking at
precipitable water values ranging from 1 to 2 standard deviations
above normal. As a result, it could end up having good
precipitation efficiency which should help mitigate some of the
abnormally dry soils. At this point, it appears like the bulk of
the cold air stays east, but with such strong dynamics with this
wave it may be able to cause the rain to change over to snow
especially Thursday night into Friday. At this point, it appears
like the precipitation may begin on Wednesday night in areas west
of the Laramie Range and then linger across the panhandle until
Friday morning. The next shortwave on the horizon may impact the
area late next weekend into early next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1103 PM MDT Sat Mar 18 2017

VFR with mainly high clouds. Westerly surface winds near 10 kt
overnight will increase by late Sunday morning. Gusts of 25-30 kt
are forecast for southeast Wyoming terminals, and 20-25 kt for
Nebraska panhandle terminals.

&&

.FIRE WEATHER...
Issued at 216 PM MDT Sat Mar 18 2017

Elevated to near critical fire weather conditions will continue
through the remainder of the afternoon over the plains of southeast
WY with RH values around 15 percent and gusts to 20-25 mph.  Another
warm and very dry day is in store for Sunday with breezy west winds
from late morning through the afternoon. Widespread critical fire
weather conditions are expected to develop over areas to the east of
the Laramie Range and a Red Flag Warning is in effect.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning from 11 AM to 7 PM MDT Sunday for WYZ310.

NE...Red Flag Warning from 11 AM to 7 PM MDT Sunday for NEZ311>313.

&&

$$

SHORT TERM...ZF
LONG TERM...REC
AVIATION...MAJ
FIRE WEATHER...ZF



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