Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus65 kcys 232031 
afdcys

Area forecast discussion
National Weather Service Cheyenne Wyoming
231 PM MDT Tue Jul 23 2019

Short term...(late this afternoon through Wednesday night)
issued at 230 PM MDT Tue Jul 23 2019

Early afternoon WV/visible imagery and surface obs showed a sprawling
north-South Ridge of high pressure over the eastern Great Plains
and MO River Valley. A high amplitude upper ridge was centered
over the Rocky Mountains. Subsidence beneath this ridge has kept
a lid on most convection. Isolated showers/weak T-storms were
developing over the Laramie, snowy and Sierra Madre ranges, and
moving to the south. Latest convective allowing models continued
to show convection forming mid-late afternoon from the southern
Laramie range east toward Cheyenne. With weak shear/winds aloft
and MUCAPES less than 1000 j/kg, main threats from stronger
convection would be locally heavy rain, small hail and gusty
outflow winds to 40 mph. Convection will dissipate early this
evening.

Short range models/ensembles agree that the upper ridge flattens
as a potent shortwave trough tracks east along the international
border Wednesday. Subtropical moisture will be pulled north and
east across the cwfa, along with weak energy aloft. Convective
coverage will be more scattered over southeast Wyoming during the
afternoon, and into the western NE Panhandle Wednesday evening.
Winds aloft will be stronger closer to the Lee trough and forcing
from eastern Montana into northeast Wyoming and the western Dakotas. The
Storm Prediction Center day2 outlook shows the southern extent of a marginal risk for
severe T-storms to near a Lusk to Alliance line. A couple of
stronger cells may produce marginally severe hail and wind gusts
during the late afternoon/early evening. It will be warmer
Wednesday with high temperatures from the mid 80s to mid 90s.
Southwesterly winds will be breezy Wednesday afternoon along
and west of the Laramie range.

Long term...(thursday through tuesday)
issued at 230 PM MDT Tue Jul 23 2019

Center of upper ridge along the Arizona-nm border retrogrades westward
to the southern Great Basin late this weekend, then eastward into
The Four Corners early next week. The more significant shortwave
activity will reside near the Canadian-U.S. Border, with weaker
waves embedded within the quasi-zonal flow aloft across the County warning forecast area.
Timing/location of these waves will determine overall convective
strength. Most of the convection will occur during the afternoons
and evenings. The severe threat will be low owing to weak shear/winds
aloft, however stronger convection may produce some locally heavy
rain, small hail and gusty winds. Convective coverage will range
from isolated to scattered, with the highest pops Thursday and
Saturday over the southeast Wyoming mountains. Temperatures will average
slightly above seasonal normals for late July.

&&

Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1119 am MDT Tue Jul 23 2019

VFR conditions are prevailing for all sites currently. Some
thunderstorms are possible early this afternoon at klar and kcys
but chances will drop off quickly as we move into the evening. VFR
conditions will then remain through the end of the period.

&&

Fire weather...
issued at 147 PM MDT Tue Jul 23 2019

Fire weather concerns will be negligible for the next several days.
Minimum humidities will fall to 15 to 20 percent over lower elevations
of Carbon County. Fuels in these areas are green. There will be
isolated to scattered afternoon and evening showers and thunderstorms
each day. Wind speeds will remain below 25 mph, except erratic and
gusty near thunderstorms.

&&

Cys watches/warnings/advisories...
Wyoming...none.
NE...none.
&&

$$

National Weather Service Glossary of Abbreviations