781
FXUS65 KCYS 252006
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
206 PM MDT SAT MAY 25 2013
SHORT TERM
(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 230 PM MDT SAT MAY 25 2013
VISIBLE SATELLITE LOOP SHOWS PARTLY CLOUDY SKIES WITH CONVECTION
JUST STARTING TO INITIATE NEAR THE NEBRASKA BORDER THIS AFTERNOON.
RELATIVELY QUIET RIGHT NOW WITH ONLY SOME VIRGA SHOWING UP ON
RADAR. SURFACE BOUNDARY/DRYLINE FEATURE JUST WENT THROUGH KIMBALL
NEBRASKA INDICATIVE OF THE SURFACE DEWPOINT DROP BY 7C IN ONLY A
HALF AN HOUR AND WINDS SHIFTED INTO THE SOUTHWEST. THIS BOUNDARY
IS LOCATED NEAR KIMBALL AND EXTENDS NORTHWEST TO NEAR GUERNSEY
WYOMING...AND FURTHER NORTH TO AROUND THE DOUGLAS AREA. THIS
BOUNDARY WILL CONTINUE TO MOVE SLOWLY EAST THIS AFTERNOON.
DEWPOINTS AHEAD OF THIS BOUNDARY ARE IN THE 50S TO NEAR 60 INTO
WESTERN NEBRASKA WITH DEWPOINTS IN THE TEENS AND 20S WEST OF THE
BOUNDARY. PRETTY GOOD CONVERGENCE ALONG THIS BOUNDARY...AND WITH
AMPLE MOISTURE AHEAD OF IT...THERE IS CONCERN FOR SEVERE
THUNDERSTORMS EAST OF A LINE FROM LUSK WYOMING TO SIDNEY NEBRASKA.
MODEL SOUNDINGS CONTINUE TO INDICATE LOW LI/S DOWN TO AROUND -7C
AND CAPE VALUES AROUND 2000 TO 2500 J/KG IN THESE AREAS WITH 30 TO
50 KNOTS OF SHEAR...ESPECIALLY OVER THE NORTHERN NEBRASKA
PANHANDLE. WILL CONTINUE TO MONITOR AND EVALUATE THE
ENVIRONMENT...WITH THE POTENTIAL OF A SEVERE TSTORM OR TORNADO
WATCH AFTER 3 PM THIS AFTERNOON.
FOR TONIGHT...THE SHORTWAVE RESPONSIBLE FOR THE STRONGER TSTORMS
WILL QUICKLY PUSH EAST OF THE FORECAST AREA LATE THIS EVENING.
THINK THE POTENTIAL FOR FOG IS A BIT LESS TONIGHT...BUT ADDED
PATCHY FOG TO LOCATIONS WHICH ARE MORE LIKELY TO SEE SOME RAINFALL
THIS EVENING. OTHERWISE...TEMPERATURES WILL REMAIN MILD TONIGHT.
FOR SUNDAY AND MONDAY...POTENTIAL FOR TSTORMS WILL SHIFT A BIT
FURTHER WEST DURING THE DAY AS ANOTHER SHORTWAVE TROUGH PUSHES
ACROSS SOUTHEAST WYOMING LATE IN THE DAY. HOWEVER...ANY SEVERE
WEATHER THREAT SHOULD SHIFT A LITTLE FURTHER NORTHEAST OVER
CENTRAL NEBRASKA AND SOUTHERN SOUTH DAKOTA. SIMILAR CONDITIONS ARE
EXPECTED ON MONDAY AS ANOTHER SHORTWAVE ALOFT TAKES A VERY SIMILAR
TRACK COMPARED TO SUNDAY...BUT THE SEVERE WEATHER THREAT WILL BE
EVEN LESS WITH DRIER NORTHWEST WINDS. TEMPERATURES WILL REMAIN
ABOVE NORMAL...BUT WILL LOWER A FEW DEGREES ON MONDAY.
LONG TERM
(TUESDAY THROUGH SATURDAY)
ISSUED AT 111 PM MDT SAT MAY 25 2013
TUESDAY...SIMILAR SOUTHWEST FLOW PATTERN ALOFT CONTINUES WITH WEAK
SHORTWAVES ROTATING NORTHEAST ACROSS OUR COUNTIES. SURFACE TROUGH
FORMS FROM CENTRAL WYOMING SOUTHEAST TO EASTERN COLORADO...ACTING AS
A FOCUS FOR ISOLATED TO SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS...SOME STRONG TO POSSIBLY SEVERE.
WEDNESDAY...INITIAL NEGATIVELY TILTED SHORTWAVE TROUGH ALOFT ROTATES
ACROSS OUR COUNTIES AND WITH ADEQUATE LOW AND MID LEVEL
MOISTURE...EXPECT SCATTERED AFTERNOON AND EVENING THUNDERSTORMS
ALONG ITS ASSOCIATED SURFACE TROUGH AXIS.
THURSDAY...SLOW MOVING STACKED UPPER TROUGH LIES ACROSS WYOMING
PRODUCING WEST AND SOUTHWEST WINDS OVER OUR COUNTIES. OUR NORTHERN
AND WESTERN COUNTIES WILL BE CLOSE ENOUGH TO THE UPPER CIRCULATION
FOR SCATTERED LATE DAY SHOWERS AND THUNDERSTORMS...WHILE DOWNSLOPING
WINDS WILL LIMIT AREAL COVERAGE FROM WHEATLAND SOUTH TO COLORADO.
FRIDAY...WINDY AND COOL DAY AS THE MAIN SHORTWAVE TROUGH ALOFT
ROTATES TO OUR EAST...PRODUCING SCATTERED LATE DAY SHOWERS AND
THUNDERSTORMS NORTH OF A DOUGLAS TO SCOTTSBLUFF LINE...WITH
DOWNSLOPING WINDS PRODUCING A RAIN SHADOW EFFECT FURTHER SOUTH.
SATURDAY...LESSER AFTERNOON AND EVENING THUNDERSTORM COVERAGE AS A
WEAK SHORTWAVE RIDGE ALOFT PREVAILS...AND LOW AND MID LEVEL MOISTURE
WANES.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 1125 AM MDT SAT MAY 25 2013
THROUGH 02Z...ISOLATED TO SCATTERED THUNDERSTORMS PRODUCING MVFR
EAST OF A LUSK TO KIMBALL LINE...OTHERWISE VFR.
07Z TO 15Z...AREAS OF IFR IN LOW CLOUDS AND FOG AT CHADRON AND
ALLIANCE...OTHERWISE VFR.
FIRE WEATHER
ISSUED AT 135 PM MDT SAT MAY 25 2013
A SURFACE BOUNDARY SEPARATING MOIST UNSTABLE AIR TO THE EAST AND
DRY STABLE AIR TO THE WEST WILL EXTEND FROM NORTHEAST WYOMING TO
THE NEBRASKA PANHANDLE. THIS BOUNDARY WILL BE THE FOCUS FOR
THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING...AND AGAIN
SUNDAY AFTERNOON. DRY CONDITIONS AND GUSTY WINDS WILL CONTINUE
ACROSS MAINLY CARBON AND ALBANY COUNTIES THIS WEEKEND...AND INTO
FAR EASTERN WYOMING BY MONDAY. TEMPERATURES WILL BE 10 TO 15
DEGREES ABOVE NORMAL THROUGH EARLY NEXT WEEK. DUE TO GREEN
FUELS...FIRE WEATHER CONCERNS REMAIN LOW.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...TJT
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...TJT
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