Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Cheyenne Wyoming
243 PM MDT Monday Aug 31 2015

Short term...(this evening through Wednesday night)
issued at 300 PM MDT Monday Aug 31 2015

Forecast challenges deal primarily with fire weather conditions on
Wednesday.

Currently...have a weak frontal boundary over the area this
afternoon. Looks like it just came through southern Wyoming as
cheyennes winds have finally turned north early this afternoon.
Radar showing some scattered thunderstorms developing over the
Snowy Range and moving into central Laramie County at this time.
Current forecast looks on track with best chances for showers and
thunderstorms along and west of the Laramie range. Convection
expected to decrease in coverage after sunset and remain mainly
west of the Laramie range.

Best chances for showers and thunderstorms for Tuesday again west
of the Laramie range. Could see some spillover into the plains of
southeast Wyoming east of the Laramie range Tuesday evening...but
coverage should be isolated to widely scattered at best. Kept
previous forecast for probability of precipitation as this looks pretty good. Attention
turns to Wednesday.

Both the GFS and European model (ecmwf) show a slow moving low pressure system
moving into the Pacific northwest Tuesday night that slowly tracks into
western Montana by late Wednesday. This is a favorable pattern
for increasing winds and dry conditions for southeast Wyoming.
GFS 700mb winds increase to 25-30kts Wednesday at 18z and remain
strong through the evening hours. GFS forecast soundings showing
areas west of the Laramie range and up in Converse County mixing
well above 600mbs Wednesday afternoon...so much of this winds is
expected to mix down to the surface. Dewpoints in the upper
twenties to low 30s should yield afternoon humidities in the low
teens area wide. Decided to issue a Fire Weather Watch for
Wednesday afternoon to give our fire customers as much advance
notice as possible.

Long term...(thursday through monday)
issued at 300 PM MDT Monday Aug 31 2015

Upper pattern will feature SW flow aloft over the County Warning Area through the
period with an upper trough initially digging over the western
Continental U.S. Before lifting northeast late in the week into early next
week. Some monsoonal moisture will be in the area Thursday into
Friday and weak impulses in the upper flow should allow for at
least isolated mainly late day convection on those days. A weak
front may help some Friday as it sinks south across the plains
with a secondary push later on Saturday. Somewhat drier but milder
weather looks to settle over the County Warning Area Sunday and Monday as a
surface high builds east into the area from the northeast Pacific
and shunts better moisture to the southeast of the County Warning Area.

&&

Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1113 am MDT Monday Aug 31 2015

VFR expected through the period. A few afternoon and evening showers
and thunderstorms possible mainly around the southern Wyoming mountains this
afternoon with brief localized MVFR and gusty and erratic wind.

&&

Fire weather...
issued at 300 PM MDT Monday Aug 31 2015

Fire weather concerns minimal today and most of Tuesday as cooler
temperatures and higher humidities remain in place. Winds begin to
increase Tuesday night into Wednesday morning though as another low
pressure system tracks into Montana. With warmer temperatures and
gustier winds...critical fire weather conditions are possible for
those fire zones where fuels are reported receptive to rapid fire
growth. Could be looking at fire headlines each day through the end
of the week as that low in Montana is slow to move through the area.

&&

Cys watches/warnings/advisories...
Wyoming...Fire Weather Watch from late Wednesday morning through
early Wednesday evening for wyz301-302-304-306.

NE...none.
&&

$$

Short term...gcc
long term...re
aviation...re
fire weather...gcc

National Weather Service Glossary of Abbreviations