000
FXUS65 KCYS 132332
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
532 PM MDT THU JUN 13 2013

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 311 PM MDT THU JUN 13 2013

MAIN FORECAST CHALLENGE AND CONCERN IN THE SHORT TERM IS THE
POTENTIAL FOR THUNDERSTORMS THE REMAINDER OF THIS AFTERNOON AND
EVENING. ISOLATED THUNDERSTORMS HAVE DEVELOPED OVER CARBON COUNTY
THIS AFTERNOON AS EXPECTED. THESE STORMS SHOULD SPREAD NORTHEAST
INTO CONVERSE COUNTY BY LATE THIS AFTERNOON. GENERALLY NOT
EXPECTING SEVERE WEATHER WITH THESE STORMS GIVEN A LACK OF CAPE
BUT GIVEN THEY WILL BE MOVING AT 40 KTS AND INVERTED V
SOUNDINGS...GUST 50 TO 60 MPH ARE A GOOD POSSIBILITY WITH
MICRO BURST NOT OUT OF THE QUESTION.

FARTHER TO THE EAST THE QUESTION IS WHETHER OR NOT STORMS WILL
EVEN BE ABLE TO FORM. SOUTH TO SOUTHEAST FLOW IN THE LOW LEVELS
AND RATHER SUBSTANTIAL MID LEVEL CLOUDS CUT BACK ON EXPECTED SURFACE
HEATING...SUCH THAT THE SURFACE CAP MAY VERY WELL HOLD EAST OF THE
LARAMIE RANGE. WILL HAVE TO KEEP CLOSE WATCH THE REST OF THE
AFTERNOON AS A HIGH SUN ANGLE THIS TIME OF YEAR CAN QUICKLY WARM
THINGS UP AND THERE IS A DECENT AREA OF LOW LEVEL CONVERCENCE
ALONG THE LARAMIE RANGE...BUT MOST LIKELY THE CAP EAST OF THE
LARAMIE RANGE WILL HOLD. OF COURSE SHOULD STORMS DEVELOP AND
BECOMING ROOTED INTO THE BOUNDARY LAYER...SEVERE THUNDERSTORMS
WITH LARGE HAIL AND DAMAGING WINDS WOULD BE LIKELY.

ANOTHER AREA OF CONCERN IS WITH THE CONVECTION FORMING OVER THE
HIGHER TERRAIN IN COLORADO. THIS CONVECTION IS EXPECTED TO SHIFT
NORTHEAST INTO THE PLAINS LATER THIS AFTERNOON. STORMS THAT MOVE
INTO THE PLAINS MAY BE ABLE TO REACH THE SOUTHERN NEBRASKA
PANHANDLE BY THIS EVENING...ALTHOUGH THE BULK OF THE THUNDERSTORM
ACTIVITY SHOULD REMAIN SOUTH OVER NORTHEAST COLORADO. THESE STORMS
COULD BE SEVERE WITH STRONG WINDS AND HAIL...EVEN A TORNADO WOULD
NOT BE OUT OF THE QUESTION. HAIL THREAT WILL BE SOMEWHAT LIMITED
BY 12000 FT AGL FREEZING LEVELS. LOW LEVEL SOUTHEAST FLOW WILL
QUICKLY VEER WITH HEIGHT WITH WESTERLY FLOW ALOFT...SO SHOULD BE
LOOKING AT 50 KTS OF DEEP LAYER SHEAR SUPPORTIVE OF
SUPERCELLS. STORMS SHOULD CONGEAL THIS EVENING...SO MAY BE
DEALING WITH A DEVELOPING MCS WITH EMBEDDED SUPERCELLS FOR
CONVECTIVE MODE.

SHOWER AND THUNDERSTORM THREAT SHOULD END BY MIDNIGHT WITH THE
MAIN UPPER LEVEL LOW WELL NORTH INTO CENTRAL MONTANA...WHILE
CONVECTION OVER THE PLAINS SHIFTS WELL TO THE EAST. THE WAVE OVER
MONTANA WILL DRIVE A COLD FRONT SOUTH AND EAST TONIGHT PUSHING
COOLER STABLE AIR INTO THE FORECAST AREA. THIS WILL GENERALLY SHUT
DOWN THUNDERSTORM CHANCES FRIDAY...ALTHOUGH THE NAM AND GFS
SUGGESTING RETURN FLOW AND ISENTROPIC FORCING NEAR THE COLORADO
BOARD BY FRIDAY EVENING. AN ELEVATED WARM FRONT COULD SPREAD A
FEW SHOWERS AND THUNDERSTORMS NORTH OVER FAR EASTERN WYOMING AND
THE NEBRASKA PANHANDLE FRIDAY EVENING. COULD AGAIN SEE SOME
THUNDERSTORM ACTIVITY IN THE PLAINS SATURDAY.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 300 PM MDT THU JUN 13 2013

UPPER RIDGE AXIS WILL HOLD TO THE WEST OF THE CWA THROUGH EARLY
NEXT WEEK WITH SEVERAL UPPER IMPULSES LIKELY TO PASS THROUGH THE
RIDGE AND ACROSS THE REGION. THESE SHOULD COMBINE WITH SOME
INSTABILITY TO PRODUCE WIDELY SCATTERED MAINLY LATE DAY SHOWERS
AND STORMS OVER THE PLAINS THROUGH TUESDAY. UPPER RIDGE AXIS WILL
PASS ACROSS MONDAY WITH SW FLOW ALOFT COMING OVER THE AREA BY
WEDNESDAY AND CONTINUING INTO THURSDAY. SFC BOUNDARY SHOULD SHIFT
EAST OVER THE HIGH PLAINS WEDS BRINGING IN SOME DRIER AIR THUS
PCPN CHANCES SHOULD DROP OFF AT THAT TIME. TEMPERATURES SHOULD BE
SEASONAL FOR THE PERIOD.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY AFTERNOON)
ISSUED AT 529 PM MDT THU JUN 13 2013

VFR CONDITIONS EXPECTED. SOME CONCERN FOR THE KSNY AIRPORT AS
LATEST RADAR LOOP SHOWING FAIRLY STRONG TSTMS NEAR AKRON COLORADO
MOVING TOWARDS THE NORTHEAST. ON PRESENT TRACK...TSTMS SHOULD PASS
JUST SOUTH OF KSNY...SO CONTINUED VCTS WORDING IN THEIR FORECAST.
CONVECTION WEST OF THE LARAMIE RANGE SHOULD DIE OFF AT SUNSET WITH
LACK OF DAYTIME HEATING.

&&

.FIRE WEATHER...
ISSUED AT 134 PM MDT THU JUN 13 2013

A FEW THUNDERSTORMS POSSIBLE THROUGH THIS EVENING THEN DRY THROUGH
FRIDAY AFTERNOON. A FEW MORE THUNDERSTORMS POSSIBLE FRIDAY EVENING
OVER FAR SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE BUT CHANCES
FOR WETTING RAIN MINIMAL.

COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT. THIS WILL PUSH COOLER
DRIER AIR OVER SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE.
HUMIDITIES WILL AGAIN PLUMMET WEST OF THE LARAMIE RANGE WITH SINGLE
DIGIT MINIMUMS INTO LOWER ELEVATIONS FRIDAY AFTERNOON. TEENS FOR
MINIMUM RELATIVELY HUMIDITY EAST OF THE LARAMIE RANGE IN SOUTHEAST
WYOMING. LOW HUMIDITY VALUES WILL BE ACCOMPANIED BY GUSTS OF 20 TO
30 MPH FRIDAY AFTERNOON WITH THE STRONGEST WINDS OVER HIGHER
ELEVATIONS. FUELS MAY NOT BE SUPPORTIVE OF EXPLOSIVE FIRE GROWTH
QUITE YET...BUT RECENT WARM DRY WEATHER MAY PUSH CONDITIONS CLOSE
TO CRITICAL. DRY CONDITIONS WILL PERSIST WEST OF THE LARAMIE RANGE
THROUGH THE FORESEEABLE FUTURE WHILE EASTERN AREAS MAY SEE HIGHER
HUMIDITIES AND THUNDERSTORMS SOME DAYS.

&&

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

$$

SHORT TERM...LIEBL
LONG TERM...RE
AVIATION...CLAYCOMB
FIRE WEATHER...LIEBL