Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Riverton Wyoming
206 PM MST Monday Feb 8 2016

Short term...tonight through Tuesday

Imagery shows amplified ridge/trough pattern west to east across the
Continental U.S....with Wyoming under northwest flow. Surface has high p across the Great Basin
into western Wyoming with lowering p to the east supporting a modest p gradient and
some breezy/gusty conditions over the wind corridor. Otherwise...only
a few middle/upper clouds across the forecast area.

Rather static pattern through the short term with mostly dry upper level
ridging remaining in control of the western Continental U.S. And the forecast area remaining
under steep northwest flow. Few to scattered areas of middle/upper cloud ring
the outside of the County Warning Area with little to no cloud over the interior.
However...even these clouds will be on the decrease through the forecast
period. With decent daytime warming melting snow...overnight/early
mornings across the some areas may allow for patchy fog formation if
low upper level flow quiets/lifts enough to keep turbulence aloft from
influencing the surface. Best bests for patchy fog will be in the western
valleys and the Wind River basin...with somewhat lesser chances over
the other basins. Breezy/gusty conditions will be in place across
the northern mountains...portions of the Upper Green basin...and the
wind corridor. highlights are expected as critical
atmospheric conditions for high wind will not be met at this time.
Otherwise...expect warming seasonal highs and lows and no precipitation.

Long term...Tuesday night through Monday

The long term period will continue to be dominated by a warm ridge
with basin and valley inversions holding in most areas but even
gradual warming is expected in these locations. A Pacific cold
front will move across the area Saturday night or Sunday bringing
chances of snow showers to the west and northern mountains. A
ridge of high pressure will rebuild over the area early next week.

The only potential for hazardous weather will be early Wednesday
when gap flow sets up along the absarokas...there could be some 60
miles per hour wind gusts near Clark and west of Cody...not sure it will be
widespread enough for a High Wind Warning but it will be watched
closely nonetheless. As a Lee trough dips east of The Divide...the
wind will also pick up between the Red Desert and Casper. While it
will be will also be warmer...with mild air possibly
mixing down for record or near record highs in the 50s and
possibly 60 near Casper...Cody...Crowheart and Buffalo Wednesday.
There is still quite a bit of snow on the ground at Casper
however...that may hold temperatures down at or below 50 degrees.

A shortwave topping the ridge and diving into the northern plains
on Thursday will provide better mixing across the lower central
basins with increasing northwest flow and cold advection in the
mid-levels. It will not amount to much in the way of precipitation
however it could have a positive affect on basin and valley
inversions...allowing them to erode a it will take a cold
front to warm up the valleys.

The next system of note moves through late in the weekend. There
is still some disagreement on the evolution of this splitting
trough but it is not expected to have much of an impact given its
current track and strength. It will likely just muster some
mountain showers on Sunday and some cooler temperatures and
gusty wind east of The Divide. However...temperatures quickly
rebound on Monday as the ridge builds back into the region.


Aviation.../00z issuance/

VFR conditions to prevail through the forecast period. The main
concern this evening will be marginal low level wind shear near
mountains and mountain turbulence due to the northwest flow aloft.
Some patchy fog/low cloud development will remain a possibility over
the far western valleys...and perhaps over the central/northern Wind
River valley overnight into the morning. Have inserted vcfg into the
kjac and kriw terminal sites for late tonight...but will keep it out
of the Upper Green river basin due to the expected continuation of
breezy northerly winds in that area.


Fire weather...

Fire danger remains low across the forecast area through the work
week...with seasonal temperatures and snow covering many surfaces.
Winds...however...will be on the breezy side today through Tuesday
across the usual wind prone area of central Wyoming.
Wednesday...areas in and adjacent to the Absaroka Mountains could
see near high wind criteria...especially through the morning hours.
Otherwise...most late mornings and afternoons across Wyoming should
see good smoke dispersion through the end of the week.


Riw watches/warnings/advisories...


Short term...Braun
long term...Allen
fire weather...Braun

National Weather Service Glossary of Abbreviations