Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 270531

Area Forecast Discussion
National Weather Service Cheyenne WY
1130 PM MDT Sun Mar 26 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 300 PM MDT Sun Mar 26 2017

Unsettled weather in the short term, extending through much of the
week. Forecast challenges deal with timing and possible switch
over to snow. There is a chance for winter weather headlines again
this upcoming week.

Currently...1001mb surface low analyzed over the Texas/Oklahoma
Panhandle region this afternoon with inverted trough extending
from this low up into southeastern Wyoming. Wrap around moisture
from this low causing cloudy skies across the CWFA. Light rain
showing up on mosaic radar along the Laramie Range and across the
southern Panhandle. We have been seeing very light rain on and
off all day today, mainly in the form of sprinkles.

This surface low continues to move east this afternoon and evening
with light rain ending across southeast Wyoming this evening.
Fairly dry day in store for Monday as the area will be under a
transitory shortwave ridge. Fairly warm Monday with highs ranging
from the low 60s east and low 50s west.

Next low pressure system moves into central California Monday
afternoon and just south of the 4 corners area Monday night into
Tuesday. 700mb low pressure forecast to be over central Colorado
by Tuesday afternoon. This is quite a bit further north than
models have indicated the previous couple days and poses the
challenges in precip type. ECMWF forecasting 700mb temperatures of
-4 to -5C over southeast Wyoming Tuesday, while GFS has -1 to -3C.
GFS being the warmer solution showing mostly rain east of the
Laramie Range with snow west for Tuesday.

Both models are showing fairly widespread precipitation Tuesday
into Tuesday night. Question is, what form is going to fall? For
now, went with rain east and snow west. In fact, have significant
snow accumulations for the Snowy Range with Storm Total snow
around 18-20 inches as they do good with this pattern.

Will let later shifts have another look at the latest model runs
before issuing any winter headlines. Think we will need some, but
for now, confidence not high on where.

.LONG TERM...(Wednesday night through Sunday)
Issued at 300 PM MDT Sun Mar 26 2017

Wednesday night/Thursday...Shortwave ridging aloft prevails
Wednesday night, producing a dry overnight. On Thursday, the next
shortwave trough aloft moves into western Wyoming, spreading its`
precipitation shield across western Wyoming with a few afternoon
showers possible over our far western counties. Relatively mild for
the penultimate day of March.

Friday...The closing upper low moves southeast, to the Four Corners
by late in the day. With a saturated airmass overhead, and deep
moist upslope, expected scattered to numerous showers to develop in
our counties.

Saturday...The upper low moves slowly eastward across central New
Mexico, with the precipitation shield across our counties moving
from west to east with precipitation ending across our western
counties in the afternoon.

Sunday...Upper trough lifts slowly northeastward into southeast
Colorado by late in the day, with precipitation ending across our
southeast Counties. Warming trend with more sunshine and less cloud


.AVIATION...(For the 06Z TAFS through Monday evening)

Main aviation concern tonight will be the potential for fog and low
stratus across western Nebraska and around KCYS. Currently seeing
MVFR CIGS at KCYS and KCDR. Waiting for the surface winds to shift
into the southwest at KCYS which should result in disipating low
clouds. Further east, light and variable winds will persist into the
early morning hours along with ample llvl moisture. Kept lower VIS
and CIGS across the area, but expect IFR conditions to mainly impact
KAIA at this time. Low clouds will lift shortly after sunrise
Monday. This will be short-lived as the next Pacific storm will
begin to impact the western terminals (KRWL and KLAR) as early as
mid Monday afternoon.


Issued at 300 PM MDT Sun Mar 26 2017

No fire weather concerns through early next week. Unsettled
weather is going to be the story through much of the upcoming week
with chances for mountains snows and valley rains. Cold to cool
temperatures with light winds and increased chances for wetting
rains will keep fire weather concerns in check. Minimum afternoon
humidity values will stay above 25 percent through Wednesday.





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