Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 251003
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
403 AM MDT MON MAY 25 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 400 AM MDT MON MAY 25 2015

PER WATER VAPOR/RADAR TRENDS...THE UPPER LOW CENTER HAS MOVED FROM
NORTHERN TO NORTHEAST CO IN THE PAST 6 HOURS. MORE INTENSE CONVECTION
ACCOMPANIED THE MAIN VORTICITY CENTER MOVING INTO CENTRAL KS. REGIONAL
RADARS SHOWED SCATTERED TO NUMEROUS RAIN SHOWERS ROTATING CYCLONICALLY
OVER THE HIGH PLAINS. RAINFALL THUS FAR HAS BEEN LIGHT TO MODERATE
INTENSITY. SURFACE FEATURES INCLUDED A STATIONARY FRONT FROM THE
SOUTHERN GREAT LAKES WESTWARD TO A LOW CENTER OVER WEST CENTRAL NE
THEN SOUTH INTO WEST TX. A WEAK INVERTED TROUGH EXTENDED NORTHWEST
FROM THE LOW INTO EAST CENTRAL WY.

UPPER LOW AND ASSOCIATED TROUGH WILL SLOWLY LIFT EAST-NORTHEAST ACROSS
TOWARD THE MID-UPPER MS VALLEY...WITH A TRANSITORY LOW AMPLITUDE
RIDGE MOVING ACROSS THE ROCKY MOUNTAIN FRONT RANGE AND HIGH PLAINS.
MOISTURE ROTATING AROUND THE DEPARTING UPPER LOW COMBINED WITH COOL
AIR ALOFT WILL KEEP CONDITIONS UNSTABLE ENOUGH FOR SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS TODAY. HIGH TEMPERATURES TODAY WILL AVERAGE
5-10 DEGREES BELOW NORMAL. SHOWER COVERAGE WILL DECREASE LATER THIS
EVENING AND FOCUS OVER THE MOUNTAINS.

WITH WEAK RIDGING ALOFT...UPSLOPE AND LOW LEVEL CONVERGENCE ALONG A
SURFACE TROUGH OVER THE HIGH PLAINS...EXPECT A MORE TYPICAL LATE
SPRINGTIME PATTERN OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
BOTH TUESDAY AND WEDNESDAY. HEIGHT FALLS ASSOCIATED WITH AN APPROACHING
UPPER TROUGH...INCREASING LOW LEVEL EAST-SOUTHEAST FLOW AND MORE
UNSTABLE ENVIRONMENT OVER THE HIGH PLAINS WILL FAVOR STRONGER CONVECTION
WEDNESDAY AFTERNOON. THE STORM PREDICTION CENTER FORECASTS A MARGINAL
RISK FOR SEVERE THUNDERSTORMS PRODUCING LARGE HAIL AND DAMAGING WINDS
FOR THE NE PANHANDLE. TEMPERATURES WILL FINALLY WARM TO SEASONAL
NORMALS WEDNESDAY.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM MDT MON MAY 25 2015

WET WEATHER CONTINUES IN THE LONG TERM...AT LEAST THROUGH THE REST
OF THE WORK WEEK...WITH DRY WEATHER RETURNING FOR THE WEEKEND.

STARTING OFF WEDNESDAY NIGHT...BOTH THE GFS AND ECMWF SHOW AN
UPPER SHORTWAVE MOVING THROUGH SOUTHEAST WYOMING INTO WESTERN
NEBRASKA. SHOULD SEE SHOWERS AND THUNDERSTORMS AT LEAST THROUGH
THE EVENING HOURS BEFORE DISSIPATING OVERNIGHT.

UPPER LEVEL DISTURBANCES CONTINUE TO MOVE THROUGH THE AREA ON AN
ALMOST DAILY BASIS THAT WILL KICK OFF CONVECTION DURING THE
AFTERNOON AND EARLY EVENING HOURS THURSDAY AND FRIDAY.

UPPER TROUGH FINALLY LOOKS TO MOVE EAST INTO CENTRAL KANSAS
SATURDAY. MOST OF THE CWFA SHOULD BE DRY SATURDAY AFTERNOON...BUT
THERE COULD BE SOME CONVECTION ACROSS THE SOUTHERN NEBRASKA
PANHANDLE TO MAYBE CHEYENNE. NICE DAY IN STORE FOR SUNDAY AS AN
UPPER LEVEL RIDGE BUILDS OVER THE AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1142 PM MDT SUN MAY 24 2015

KEPT TREND OF DROPPING VISIBILITIES AND CEILINGS INTO IFR CATEGORY
FOR CHADRON...ALLIANCE AND SIDNEY WHERE WRAP AROUND LOW CLOUDS AND
PATCHY LIGHT RAINS ARE INDICATED TO CONTINUE IN THE HRRR AND NAM
THROUGH MORNING...WITH CEILINGS AND VISIBILITIES DROPPING INTO MVFR
AT SCOTTSBLUFF...CHEYENNE...LARAMIE AND RAWLINS THROUGH MORNING.
FOR CHEYENNE...HRRR SEEMS TO HAVE A DECENT HANDLE ON BATCH OF RAIN
MOVING SOUTHWEST OUT OF THE SCOTTSBLUFF AREA...MOVING IT TO NEAR
CHEYENNE BY DAYBREAK...SO AROUND 10Z WE BROUGHT IN SOME LIGHT RAIN
FOR CHEYENNE BUT DID NOT FEEL CONFIDENT ENOUGH TO GO IFR ON CEILINGS
OR VISIBILITIES AT THIS TIME. OTHERWISE...AS THE LOW CLOUDS START
TO SHOW SOME BREAKS BY EARLY AFTERNOON MONDAY WE EXPECT TO SEE
SCATTERED SHOWERS AND THUNDERSTORMS DEVELOP AND EITHER HAVE VICINITY
THUNDER OR CARRIED THUNDER FOR ALL SITES IN THE MID AFTERNOON HOURS
INTO EARLY EVENING.

&&

.FIRE WEATHER...
ISSUED AT 155 AM MDT MON MAY 25 2015

NON-CRITICAL FIRE WEATHER CONDITIONS ARE FORECAST DUE TO PLENTIFUL
MOISTURE FROM RECENT MODERATE TO HEAVY RAINFALL. WITH THE UPPER
LOW SLOWLY EXITING THE REGION TODAY...THERE WILL STILL BE GOOD
CHANCES FOR SHOWERS AND ISOLATED THUNDERSTORMS. WARMER AND SLIGHTLY
DRIER CONDITIONS WILL RETURN TUESDAY AND LAST THROUGH THE END OF
THE WEEK. HOWEVER...A MOIST SOUTHWEST FLOW ALOFT WITH WEAK DISTURBANCES
AND LOW LEVEL UPSLOPE WILL RESULT IN MAINLY AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS.

&&

.HYDROLOGY...
ISSUED AT 310 AM MDT MON MAY 25 2015

RECENTLY UPDATED THE FLOOD WARNING FOR THE LARAMIE RIVER NEAR FORT
LARAMIE IN GOSHEN COUNTY WY. RUNOFF AND ADDITIONAL WATER RELEASES
FROM THE GRAYROCKS RESERVOIR UPSTREAM PUSHED THE STAGE TO MODERATE
SEVERITY AT 8.2 FEET. THE RIVER IS FORECAST TO CREST AT 8.3 FEET
THIS MORNING. HIGH WATER LEVELS WILL CONTINUE AT LARAMIE THIS WEEK
AS THE RIVER FLUCTUATES BETWEEN 7.5 AND 7.7 FEET.

FORECAST RAINFALL FROM SHOWERS AND ISOLATED THUNDERSTORMS DURING THE
NEXT 24 HOURS WILL RANGE FROM LESS THAN A 0.25 INCH ALONG AND WEST OF
THE LARAMIE RANGE TO AS MUCH AS 0.75 INCH OVER WESTERN NE PANHANDLE.
LOCALLY HEAVIER AMOUNTS WILL BE POSSIBLE WITH SLOWER MOVING THUNDERSTORMS.
MORE SCATTERED DIURNALLY DRIVEN CONVECTION WILL RESUME TUESDAY AS
THE UPPER LOW EXITS THE REGION.

&&

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

$$

SHORT TERM...MAJ
LONG TERM...GCC
AVIATION...JG
FIRE WEATHER...MAJ
HYDROLOGY...MAJ



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