Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 232324
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
524 PM MDT TUE SEP 23 2014

.UPDATE...
ISSUED AT 509 PM MDT TUE SEP 23 2014

ADDED A FEW SPRINKLES TO THE FORECAST THROUGH EARLY THIS EVENING
BUT A VAST MAJORITY OF THE AREA WILL STAY DRY. COULD POSSIBLY SEE
A LIGHTNING STRIKE OR TWO IN THE NEXT FEW HOURS...BUT DO NOT
ANTICIPATE ANY FULL FLEDGED THUNDERSTORMS...ONLY SMALL CONVECTIVE
CELLS. ALL CONVECTION WILL QUICKLY WEAKEN AND DIE OFF BY MID
EVENING AS THE REMAINING UPPER LEVEL SUPPORT SHIFTS EAST AND THE
BOUNDARY LAYER QUICKLY STABILIZES AS THE SUN SETS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 251 PM MDT TUE SEP 23 2014

UPPER LOW HAS FINALLY REACHED THE DAKOTAS THIS AFTERNOON LEAVING
BEHIND A MID-LEVEL COLD POOL DRIVEN CU FIELD ACROSS THE CWFA.
REGIONAL RADAR RETURNS ALSO SHOW WK SHOWER DEVELOPMENT OVR THE NRN
NEBRASKA PANHANDLE AND OFF THE ERN SLOPES OF THE BIGHORNS. CU
FIELD COVERAGE WILL LIKELY PEAK AT TIME OF MAX HEATING...WHICH IS
2-3P THIS TIME OF YEAR. OTHERWISE...WILL SEE A RETURN TO DRY
CONDITIONS FOR THE REST OF THE PERIOD TONIGHT THRU THURSDAY NIGHT
AS AN AMPLIFIED LONGWAVE TROUGH OVR THE ERN PACIFIC INDUCES
UNSEASONABLY STRONG RIDGING ACROSS THE INTERMOUNTAIN WEST. H7
TEMPERATURES WILL WARM TO AROUND 12C FOR WEDNESDAY AND 14C ON
THURSDAY. NEAR RECORD HIGH TEMPERATURES ARE EXPECTED ON WEDNESDAY
WITH MOST RECORDS IN JEOPARDY OF BEING SURPASSED ON THURSDAY.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 251 PM MDT TUE SEP 23 2014

A CHALLENGING FCST FOR THE EXTENDED PERIOD. WARM AND DRY CONDITIONS
ARE EXPECTED TO CONTINUE THROUGH THE WEEKEND AS UPPER-LEVEL RIDGING
REMAINS INTACT OVER SOUTHEAST WY AND THE WESTERN PANHANDLE. COLUMN
ALOFT APPEARS QUITE DRY WHICH SHOULD AID IN PLENTY OF SUNSHINE. NO
PCPN IS EXPECTED WITH LARGE SCALE SUBSIDENCE. ANOTHER DAY WITH H7
TEMPS AVERAGING AROUND 12 DEG C SHOULD GIVE WAY TO WIDESPREAD 80S TO
NEAR 90 F FOR HIGHS. BIG QUESTIONS ARISE FOR THE LATTER HALF OF THE
WEEKEND INTO EARLY NEXT WEEK AS GFS AND ECMWF DIFFER SIGNIFICANTLY
IN HANDLING A POTENT STORM SYSTEM MOVING ACROSS THE WESTERN US. GFS
IS MORE MOIST WITH MORE OF A CLOSED LOW BEING KICKED NORTHEAST BY A
NORTHERN STREAM WAVE OVER BC. THE ELONGATED WAVE SUGGESTED BY THE EC
YIELDS A NOTABLE DRY SLOT OVER THE CWA THROUGH 00Z MON. BOTH MODELS
SUGGEST AN INCREASE IN DEEP MOISTURE AND QG ASCENT AFTER THAT TIME
SO AM CONFIDENT WE WILL SEE AN INCREASE IN PCPN FROM THE W. ECMWF H7
TEMPS ARE SUFFICIENTLY COLD FOR MOUNTAIN SNOW BUT THE FAST MOVEMENT
OF THE SYSTEM SHOULD PREVENT SIGNIFICANT ACCUMULATIONS. LOWERED OR
REMOVED POPS ENTIRELY FOR THE PANHANDLE FOR SUN AND MON AS THE BEST
FORCING STAYS WEST AND GUIDANCE SHOWS LITTLE IN THE WAY OF QPF. DID
NOT MAKE ANY MAJOR CHANGES TO THE GRIDS GIVEN THE LATEST
MODEL-TO-MODEL AND RUN-TO-RUN INCONSISTENCIES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY AFTERNOON)
ISSUED AT 509 PM MDT TUE SEP 23 2014

A FEW WEAK CONVECTIVE CELLS WILL BE FOUND OVER FAR SOUTHEAST
WYOMING AND INTO THE NEBRASKA PANHANDLE THROUGH EARLY THIS
EVENING...OTHERWISE CLEAR SKIES WILL PREVAIL ACROSS THE REGION FOR
TONIGHT AS UPPER LEVEL LOW PRESSURE PUSHES EAST ACROSS THE PLAINS.
LIGHT WINDS WILL BE IN PLACE THROUGH THE TAF PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 251 PM MDT TUE SEP 23 2014

A DRY PERIOD SHAPING UP ACROSS THE DISTRICT THROUGH THE END OF THE
WEEK AS A RIDGE OF HIGH PRESSURE TAKES HOLD. HIGH TEMPERATURES WILL
LIKELY THREATEN RECORDS ON WEDNESDAY AND ESPECIALLY ON THURSDAY.
WINDS DONT LOOK ESPECIALLY STRONG WED-FRI...BUT MINIMUM RELATIVE
HUMIDITIES WILL FALL TO NR CRITICAL LEVELS ESPECIALLY THURSDAY AND
FRIDAY.

&&

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

&&

$$

UPDATE...SML
SHORT TERM...HAHN
LONG TERM...HAMMER
AVIATION...SML
FIRE WEATHER...HAHN





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