Area Forecast Discussion
Issued by NWS Cheyenne, WY

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189
FXUS65 KCYS 260932
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
332 AM MDT MON SEP 26 2016

.SHORT TERM...(Today through Wednesday)
Issued at 311 AM MDT Mon Sep 26 2016

Today...Perfect early autumn days on tap for the next several days.
Northwest flow aloft weakens today as the heights increase with the
ridge moving closer. Based on thicknesses and 700 mb temperatures
near 6 Celsius, will stick close and compromise with the NAM and GFS
MOS high temperatures.

Tonight...Not quite as cool as this morning as the airmass begins to
moderate.

Tuesday...Warming trend continues as the 1000-500 mb thicknesses
continue to rise and the 700 mb temperatures warm to near 10
Celsius. Again, guidance temperatures were close and have
compromised between the NAM and GFS MOS highs.

Tuesday night...With the moderating airmass, minimum temperatures
will be a few degrees warmer than those of Monday night.

Wednesday...Ridging aloft keeps it mild and dry. Temperatures
slightly cooler, though still above normal, as thicknesses fall
slightly and 700 mb temperatures cool to near 8 Celsius, and with
surface winds becoming east and southeast.


.LONG TERM...(Wednesday Night through Sunday)
Issued at 311 AM MDT Mon Sep 26 2016

The main concern with this portion of the forecast package is the
timing of the passage of the upper level trof this upcoming
weekend.

A mild and mostly dry pattern is expected through Friday.
However, there is some question on whether a weak impulse will be
able to propagate through the region on Friday. If this does
occur, we may see a few orographic showers develop over the
mountains. However, the moisture will be rather scarce, so any
showers that do develop will not result in much precipitation.
Gusty southwest winds are also expected to develop ahead of the
main trof in the Pacific Northwest mainly west of the Laramie
Range. The next question will be the timing of the shortwaves
moving through the trof in the northwest. The GEFS ensembles are
very similar to the ECMWF in delaying the shortwaves until late
in the weekend. This will most likely result in a slight cool
down, but the bigger cool down appears to be next week as the
upper level trof begin to build southeast.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday evening)
Issued at 800 PM MDT Sun Sep 25 2016

VFR. Light and variable winds increase to 10-15 kt after 16Z Monday.
Gusts up to 20 kt possible for terminals east of the Laramie Range
Monday afternoon.


&&

.FIRE WEATHER...
Issued at 311 AM MDT Mon Sep 26 2016

Minimal concerns based on projected humidities and
winds, staying above critical thresholds.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

$$

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



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