National Weather Service Raw Text Product

920 
FXUS65 KCYS 150525
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1124 PM MDT SUN JUL 14 2013

.UPDATE...
ISSUED AT 848 PM MDT SUN JUL 14 2013

OVERALL AN UNEVENTFUL EVENING ACROSS THE CWA...DESPITE THE SURFACE
DEWPOINTS IN THE 60S AND PRECIPITABLE WATER VALUES THAT ARE
RUNNING 150 TO 200 PERCENT OF NORMAL. THICKER DAYTIME CLOUD COVER
CERTAINLY THWARTED SOME OF THE INSTABILITY. BUT THE PRIMARY
HINDRANCE HAS BEEN THE LACK OF A TRIGGER. THE ORIGINAL THOUGHT WAS
THAT OROGRAPHIC ASCENT WOULD BE SUFFICIENT IN CONVECTIVE
DEVELOPMENT...WHICH OBVIOUSLY HAS NOT BEEN THE CASE. OUTSIDE OF
A FEW ISOLATED THUNDERSTORMS...MUCH OF THE CWFA HAS REMAINED DRY.
INITIAL LOOK AT 00Z GUIDANCE SHOWS ANY HOPE OF CONVECTION FADING
THROUGH THE OVERNIGHT HOURS AS RIBBON OF MOISTURE THINS AS IT
BACKS TO THE WEST THROUGH THE CWA. COULD STILL SEE SOME SHOWERS
AND EVEN EMBEDDED THUNDER DEVELOP THRU THE NIGHT...BUT ANY HOPE IS
QUICKLY FADING. SO...IN AN EARLIER UPDATE BEGAN SCALING BACK
PRECIPITATION CHANCES ACROSS THE ENTIRE AREA TONIGHT. THE OTHER
CONCERN IS THE POTENTIAL FOR FOG DEVELOPMENT AFTER MIDNIGHT GIVEN
THE VERY MOIST LLVLS. BOTH THE SREF AND HRRR ARE POINTING TO ITS
DEVELOPMENT ALONG THE LARAMIE RANGE AND ADJACENT EASTERN
FOOTHILLS. GIVEN ESE LLVL FLOW...THIS SEEMS TO BE PLAUSIBLE. SO
HAVE ADDED AREAS OF FOG ACROSS MOST OF THE EASTERN PLAINS FOR LATE
TONIGHT AND EARLY MONDAY. 

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 350 PM MDT SUN JUL 14 2013

VERY MOIST AIRMASS IS CURRENTLY OVER THE CWA WITH MANY AREAS TO
THE EAST OF THE LARAMIE RANGE SEEING 60S DEWPOINTS. THE EXTENSIVE
LOW AND MIDLEVEL CLOUD COVER THAT HAS OCCURRED THROUGH THE EARLY
AFTERNOON HAS LIMITED SFC HEATING AND INSTABILITY. HOWEVER...VISIBLE
IMAGERY SHOWS THE PLAINS STARTING TO CLEAR AND LAPS ANALYSIS
INDICATES WIDESPREAD 500-1000 J/KG OF CAPE. BELIEVE THERE COULD BE
AN UPTICK IN CONVECTIVE ACTIVITY DURING THE EARLY EVENING OVER THE
SOUTHERN ZONES DESPITE THE LATE START. THE SFC TROUGH AND
ASSOCIATED HIGHEST DEWPOINT/PW VALUES IS JUST TO THE EAST OF THE
CWA AND IS PROGGED TO CONTINUE MOVING WESTWARD THROUGH THE NIGHT.
THE MOST IMPRESSIVE CONVECTION IS CURRENTLY IN THE CONVERGENCE
ALONG THAT TROUGH...OUTFLOW FROM THIS CONVECTION SHOULD BE ABLE TO
INITIATE CONVECTION IN THE SOUTHERN PANHANDLE DURING THE EVENING.
STILL HAVE HEAVY RAIN IN THE GRIDS THROUGH THE NIGHT WITH PW
VALUES AROUND 1.3 INCHES AND SLOW STEERING FLOW (700-300MB FLOW IS
AROUND 5-10 KTS). AREAS IN SCOTTS BLUFF COUNTY PICKED UP AROUND 2
INCHES OF RAINFALL IN A FEW HOURS EARLIER THIS AFTERNOON...A
TESTAMENT TO THE HEAVY RAIN POTENTIAL. THE PW RIDGE AXIS IS IN
EXTREME SOUTHEAST WY BY MONDAY MORNING SO CONTINUED THE THREAT OF
SHOWERS THROUGH THE NIGHT ACROSS MUCH OF THE PLAINS.

UPPER LOW AND ITS ASSOCIATED MIDLEVEL MOISTURE PLUME CONTINUE TO
MOVE WESTWARD ON MONDAY. PW VALUES ARE HIGHEST (AROUND 1 INCH)
ACROSS SOUTHEAST WY WITH A CONSIDERABLE DROP IN THE PANHANDLE.
HAVE CHANCE POPS MAINLY ALONG AND WEST OF THE LARAMIE RANGE DURING
THE AFTN AND EVENING...NOT EXPECTING MUCH FURTHER EAST. STEERING
FLOW CONTINUES TO BE WEAK SO THE HEAVY RAIN THREAT WILL BE
THERE...ESPECIALLY IN THE HIGHER TERRAIN WHERE COVERAGE OF STORMS
WILL BE BEST. TEMPS WARM AROUND 5 DEGREES ON MONDAY WITH LESS
CLOUD COVER...ESPECIALLY IN NEBRASKA. THE DRYING TREND THAT HAS
BEEN PROGGED FOR TUESDAY CONTINUES TO LOOK ON TRACK. WITH PW
VALUES AT 0.5-0.75 INCHES AND LI VALUES ON THE GFS STRUGGLING TO
GET NEGATIVE...STORM POTENTIAL WILL REALLY DROP OFF. SLIGHT CHANCE
POPS ARE CONFINED TO THE SIERRA MADRE AND SNOWY RANGES. 

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 PM MDT SUN JUL 14 2013

TUESDAY NIGHT...EVENING THUNDERSTORMS ACROSS THE SIERRA MADRE RANGE 
IN UPSLOPE...OTHERWISE DRY. 

WEDNESDAY...UPPER RIDGE AXIS OVER OUR COUNTIES. SURFACE LOW AND LOW 
LEVEL CONVERGENCE AXIS OVER OUR SNOWY AND SIERRA MADRE RANGES...
WHERE SCATTERED AFTERNOON THUNDERSTORMS ON TAP...DRY ELSEWHERE WITH 
SUBSIDENCE AND CONVECTIVE INHIBITION.

THURSDAY...RIDGE ALOFT WEAKENS SLIGHTLY AND WITH SLIGHTLY MORE LOW 
AND MID LEVEL MOISTURE...EXPECT SCATTERED AFTERNOON THUNDERSTORMS 
OVER THE NORTHERN...SNOWY AND SIERRA MADRE RANGES...DRY ELSEWHERE.

FRIDAY...MONSOONAL MOISTURE TAP RETURNS OVER OUR COUNTIES AND WITH 
LOW LEVEL UPSLOPE WINDS AND PLENTY OF LOW AND MID LEVEL MOISTURE...
WILL SEE SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS...MOST 
NUMEROUS OVER THE MOUNTAINS.

SATURDAY...DEEPER MONSOONAL MOISTURE FEED TRANSLATES SOUTH ACROSS 
COLORADO...THOUGH STILL ENOUGH MOISTURE FOR ISOLATED TO SCATTERED 
LATE DAY THUNDERSTORMS FOCUSED NEAR THE MOUNTAINS.

SUNDAY...DRIER AIRMASS ADVECTS IN ON NORTHWEST FLOW ALOFT...THUS 
ONLY ISOLATED LATE DAY THUNDERSTORMS ON TAP OVER THE MOUNTAINS...DRY 
ELSEWHERE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 1124 PM MDT SUN JUL 14 2013 

FAIRLY WIDESPREAD IFR/LIFR CIGS EXPECTED ACROSS MUCH OF THE NEB 
PANHANDLE INTO FAR ERN WYOMING INTO MONDAY MORNING IN MOIST UPSLOPE 
FLOW.  AREAS OF FOG AS WELL LOWERING VSBYS TO LESS THAN 3 MILES IN 
SOME SPOTS.  CONDITIONS SHOULD IMPROVE SLOWLY AFTER SUNRISE.  
ISOLATED SHOWERS AND A FEW TSTRMS POSSIBLE MONDAY AFTERNOON INTO 
MONDAY EVENING MAINLY OVER AND EAST OF THE MTNS.

&&

.FIRE WEATHER...
ISSUED AT 350 PM MDT SUN JUL 14 2013

NO FIRE WEATHER CONCERNS THROUGH EARLY NEXT WEEK. A VERY MOIST
AIRMASS IS CURRENTLY AFFECTING THE REGION WITH SCATTERED SHOWERS
AND THUNDERSTORMS POSSIBLE THROUGH THE EARLY NIGHT. THIS MOIST
AIRMASS WILL CONTINUE MOVING WESTWARD WITH ANOTHER CHANCE OF
SHOWERS AND THUNDERSTORMS ON MONDAY AFTERNOON AND EVENING...MAINLY
ALONG AND WEST OF THE LARAMIE RANGE. STORM CHANCES WILL REALLY
DROP BY TUESDAY AS MIDLEVEL MOISTURE PUSHES OUT OF THE REGION.
WINDS WILL GENERALLY BE BELOW 20 MPH THROUGH TUESDAY...EXCEPT IN
THE VICINITY OF STORMS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&

$$

UPDATE...HAHN
SHORT TERM...FINCH
LONG TERM...RUBIN
AVIATION...RE
FIRE WEATHER...FINCH