<message to="mfannin2@nwws-oi.weather.gov/jaxl#a20cc823625d586c32d7eedaf70a07b1" type="groupchat" from="nwws@conference.nwws-oi.weather.gov/nwws-oi"><body>KCYS issues Area Forecast Discussion (AFD) valid 2024-06-01T02:11:00Z</body><html xmlns="http://jabber.org/protocol/xhtml-im"><body xmlns="http://www.w3.org/1999/xhtml">KCYS issues Area Forecast Discussion (AFD) valid 2024-06-01T02:11:00Z</body></html><x xmlns="nwws-oi" id="nwws_processor.3611" issue="2024-06-01T02:11:00Z" ttaaii="FXUS65" cccc="KCYS" awipsid="AFDCYS"><![CDATA[

208

FXUS65 KCYS 010211

AFDCYS



Area Forecast Discussion

National Weather Service Cheyenne WY

811 PM MDT Fri May 31 2024



.UPDATE...

Issued at 800 PM MDT Fri May 31 2024



Frontal boundary currently stationary across the Laramie Range this

evening with westerly winds at Laramie and south to southeast

winds reported about 10 miles east of the highest foothills of

the Laramie Range. Do not expect this front to eject eastward

until early Saturday morning. With increasing east to southeast

winds over the high plains and current obs showing increasing

dewpoints (moisture advection), added patchy fog to the

forecast. Do not think the fog will be dense, but ceiling of 300

to 800 feet is close enough for fog...especially along the

elevated ridges. Fog or low stratus is forecast to dissipate

quickly Saturday morning as the front lifts northeast as a warm

front...this will set the stage for isolated or widely scattered

severe thunderstorms east of I-25 Saturday afternoon and evening.





&&



.KEY MESSAGES...



- Daily chances for isolated to scattered showers and  thunderstorms 

continue through the weekend. A few storms may  have the potential 

to become strong to severe each day.



- Warm and dry weather is expected most of next week, aside from  an 

uncertain potential for a cold front which could bring some 

shower/storm activity on Tuesday or Wednesday.



&&





.SHORT TERM /THROUGH SUNDAY NIGHT/...

Issued at 150 PM MDT Fri May 31 2024



Surface high pressure located over southwest South Dakota this

afternoon creating an easterly surface wind component over the

eastern half of the CWA. Stratus this morning east of the 

Laramie Range has been persistent and slow to break up in 

southeast low level upslope flow. 1PM temperatures remain quite 

cool with upper 50s in the Panhandle and southeast Wyoming 

plains east of the Laramie Range. Cheyenne finally broke out 

maybe an hour or so ago. Latest SPC Mesoanalyst page showing

quite a bit on CIN across the Panhandle into southeast Wyoming

in these southeast winds and stratus. Where skies are 

clearing...current SBCAPE has risen to 500-1000 J/KG across 

western Laramie County into southern Platte County. Lack of 

surface heating from the low clouds shows SBCAPE not rising too 

much through the afternoon with low level CIN returning by 00Z.



Given the persistent stratus...do not think we will see much

this afternoon convection wise. Another late night show possible

as a dry cold front drops into the southeast Wyoming plains as 

parent upper shortwave tracks across eastern Montana and western

SOuth Dakota. HRRR and RAP simulated radar showing convection

developing across the northern Nebraska Panhandle towards 06Z

tonight that could become strong to severe for a time through

11Z. 



Really questionable on severe convection Saturday as GFS showing

really dry air pushing into the Panhandle. Dryline on the GFS 

pushes through the Panhandle by 21Z Saturday. So its not 

matching up well with peak heating. Confidence not high on 

severe convection Saturday afternoon/evening and the SPC Slight

Risk area. Guess it depends on timing of the dryline moving 

eastward. A slower timing would improve severe convection 

chances. Later shifts will need to watch the timing of the 

dryline push. 



As for Sunday...it all depends on the timing of the dryline 

push on Saturday. Could see a dry forecast for Sunday...but for

now...kept chance PoPs (30-40 percent) for Sunday afternoon.



&&



.LONG TERM /MONDAY THROUGH FRIDAY/...

Issued at 150 PM MDT Fri May 31 2024



The long term looks relatively uneventful with mostly dry and mild 

conditions expected throughout next week. Quasi-zonal flow for the 

first half of the work week will lead to breezy and windy conditions 

across much of the CWA. A strong shortwave trough passing just to 

the north of the CWA on Tuesday will lead to the greatest potential 

for high winds across the southeast Wyoming wind prones. The GFS has 

700 mb wind speeds of 50 to 60 kts, and elevated CAG to CPR 700 mb 

height gradients. In-house guidance is also pinging the potential 

for high winds around the wind prones. Cannot rule out some slight 

precipitation chances with the passage of this shortwave either. 

Cooler temperatures can also be expected on Tuesday as the shortwave 

ushers in slightly cooler 700 mb air. By Wednesday, ridging begins 

to build over western CONUS, leading to a warmer and drier airmass 

infiltrating the CWA. Temperatures through Friday will gradually 

increase, with most locations seeing highs in the 80s by Friday. 

Minimal precipitation chances are expected during this time frame as 

subsidence keeps conditions dry.



&&



.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...

Issued at 505 PM MDT Fri May 31 2024



Another round of showers and thunderstorms are possible near the

KCDR terminal, but the primary aviation concern will be low

ceilings and potentially some fog across the Nebraska terminals

and KCYS. Could see MVFR to near-IFR conditions at KCYS, with

similar conditions at KBFF, KCDR, and KSNY. KAIA looks to drop

into the IFR to near-LIFR conditions overnight as ceilings crash

to 700ft and visibility is reduced to 2SM. Fog and low stratus

should move out of the terminals by 14Z and VFR conditions will

return. Some sites could see an oscillation between SCT010 and

BKN010 leading to frequent changes between good conditions and 

poor conditions.



&&



.CYS WATCHES/WARNINGS/ADVISORIES...

WY...None.

NE...None.



&&



$$



UPDATE...TJT

SHORT TERM...GCC

LONG TERM...SF

AVIATION...AM

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