Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KCYS 312249
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
449 PM MDT SUN MAY 31 2015

.UPDATE...
ISSUED AT 445 PM MDT SUN MAY 31 2015

WE ARE SENDING OUT A QUICK UPDATE TO LOWER POPS DURING THE
REMAINDER OF THE AFTERNOON AND EVENING ACROSS AREAS EAST OF THE
LARAMIE RANGE. DRIER AIR HAS LIMITED THE CONVECTION CHANCES ALONG
AND EAST OF THE LARAMIE RANGE THIS AFTERNOON. WE ARE CONTINUING TO
GET A ISOLATED SHOWERS AND THUNDERSTORMS FESTER IN THE SNOWY RANGE
AND SOME POINTS EAST. OTHERWISE...CONVECTION CHANCES LOOK TO BE
FAIRLY SLIM THIS EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 220 PM MDT SUN MAY 31 2015

LATEST RADAR LOOP WAS SHOWING THE BULK OF THE SCATTERED SHOWERS
AND THUNDERSTORMS DEVELOPING IN AREAS JUST EAST/SOUTHEAST OF THE
SNOWY AND SOUTHERN LARAMIE RANGES. HOWEVER...WE ARE ALSO WATCHING
THE NORTHERN LARAMIE RANGE. LATEST VISIBLE IMAGERY WAS SHOWING THE
CUMULUS FIELD STARTING TO FESTER IN THIS REGION DURING THE LAST
HOUR. PLATTE AND GOSHEN COUNTIES ARE CURRENTLY SHOWING DEWPOINTS
IN THE UPPER 40S WHICH IS A BIT DRIER THAN EARLIER IN THE DAY.
THIS STILL MAY BE ENOUGH TO KICK OFF THUNDERSTORMS IN THIS AREA
DURING THE NEXT HOUR OR SO. IF THESE STORMS MOVE SOUTHEAST TOWARDS
THE NEBRASKA PANHANDLE...THEY MAY HAVE A BETTER SHOT AT BECOMING
STRONGER DUE TO BETTER INSTABILITY. FOR NOW...WE WILL KEEP THE
HIGHEST CHANCES OF THUNDERSTORMS BETWEEN TORRINGTON AND KIMBALL
DURING THE REMAINDER OF THE AFTERNOON. ALTHOUGH...IF THE STORMS DO
NOT GET GOING THEN THE CO/WY BORDER WILL BE THE MAIN FOCUS. THESE
CLUSTERS OF SHOWERS AND STORMS SHOULD BEGIN TO DISSIPATE AROUND
SUNSET DUE TO LIMITED SHEAR TO KEEP THEM GOING. OTHERWISE...CLEAR
TO PARTLY CLOUDY SKIES WILL BE THE RULE.

MONDAY-MONDAY NIGHT:
LATEST WATER VAPOR LOOP WAS SHOWING A FAIRLY INTENSE UPPER LEVEL
TROF BEGINNING TO APPROACH NORTHERN CALIFORNIA WITH THE AIRCRAFT
DATA NOW SHOWING AN 80KT JET STREAK ROTATING THROUGH THE BASE.
THIS UPPER LEVEL TROF IS PROGGED TO SHIFT NORTHEAST INTO THE
PACIFIC NORTHWEST BY MONDAY EVENING. THIS WILL ALLOW THE UPPER
LEVEL JET AND POTENTIAL VORTICITY ANOMALIES TO KICK OUT INTO THE
NORTHERN ROCKIES. MEANWHILE...OUR REGION WILL BE UNDER THE
INFLUENCE OF THE UPPER LEVEL RIDGE THROUGH THE MORNING...BUT THIS
RIDGE AXIS IS EXPECTED TO SHIFT EAST TOWARD THE NEBRASKA PANHANDLE
DURING THE AFTERNOON. THIS WILL SET THE STAGE FOR UPPER LEVEL
DIFFLUENCE ACROSS THE MOUNTAIN RANGES DURING THE EARLY AFTERNOON
WITH THIS CONVECTION SPREADING EAST INTO THE PLAINS AND THE
NEBRASKA PANHANDLE DURING THE REMAINDER OF THE AFTERNOON INTO THE
EVENING. SOME OF THE STORMS MAY BECOME STRONG ESPECIALLY IN THE
NEBRASKA PANHANDLE WHERE THE INSTABILITY WILL BE THE GREATEST.
HOWEVER...THE 0-6KM SHEAR WILL BE QUITE MARGINAL TO SUPPORT ANY
SEVERE CONVECTION.

WE DID KEEP A SMALL CHANCE OF CONVECTION GOING IN THE NORTHEAST
PORTION OF THE FORECAST LATE (CHADRON AND LUSK) MONDAY NIGHT AS
A JET STREAK LIFTS NORTHEAST INTO NORTHERN WYOMING. THE MODELS ARE
SHOWING SOME ISENTROPIC LIFT IN THAT REGION WHICH MAY SPARK A FEW
SHOWERS AND THUNDERSTORMS.

TUESDAY-TUESDAY NIGHT:
THE SURFACE LOW IS EXPECTED TO LIFT INTO THE NORTHERN PLAINS ON
TUESDAY WHICH WILL ALLOW FOR DOWNSLOPE FLOW TO PREVAIL OVER THE
REGION. THIS SHOULD ALSO ALLOW FOR THE INSTABILITY AXIS TO SHIFT
EAST INTO THE FAR EASTERN SECTIONS OF THE PANHANDLE TUESDAY
AFTERNOON. THIS DOWNSLOPE FLOW WILL YIELD IN A DRY AND VERY WARM
DAY ACROSS MUCH OF THE AREA WITH A SMALL CHANCE OF STRONG TO
SEVERE STORMS MAINLY IN THE FAR EAST PORTIONS OF THE PANHANDLE.
THIS CHANCE OF STORMS MAY LINGER IN THE EASTERN PORTIONS OF THE
PANHANDLE DURING THE EARLY EVENING...BUT THINGS SHOULD BEGIN TO
SHIFT OUT OF THE AREA BY MIDNIGHT.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 300 PM MDT SUN MAY 31 2015

THE MEDIUM-RANGE MODEL GUIDANCE OVERALL IS IN DECENT AGREEMENT WITH
THE LARGE SCALE PATTERN. LOW AMPLITUDE RIDGE OVER THE CENTRAL AND
SOUTHERN PLAINS WILL AMPLIFY LATE IN THE WEEK AS THE NEXT EASTERN
PACIFIC TROUGH DEEPENS OVER THE WEST. THIS WILL INCREASE THE SOUTHWEST
FLOW ALOFT WITH A SERIES OF SHORT WAVES EJECTING NORTHEAST FROM THE
FOUR CORNERS ACROSS THE CENTRAL ROCKIES AND HIGH PLAINS. THESE WAVES
WILL PROVIDE LIFT FOR CONVECTION WEDNESDAY AND FRIDAY. A SURFACE TROUGH
ORIENTED NORTH TO SOUTH EAST OF THE FRONT RANGE WILL PROVIDE ADDITIONAL
LOW LEVEL CONVERGENCE FOCUS FOR CONVECTION. TSTORM DEVELOPMENT WILL
BE FAVORED DURING THE AFTERNOON AND EVENING PERIODS WITH SHOWERS AT
NIGHT. BEST CHANCES FOR STRONGER CONVECTION WILL BE OVER THE HIGH
PLAINS WITH SBCAPES OF 1000-2000 J/KG AND MARGINAL SHEAR. TEMPERATURES
WILL GRADUALLY COOL FROM SEASONAL NORMALS WEDNESDAY TO BELOW SEASONAL
NORMALS FOR THE REMAINDER OF THE LONG TERM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1142 AM MDT SUN MAY 31 2015

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER
SOUTHEAST WY AND WESTERN NE PANHANDLE BETWEEN 18Z AND 03Z. THE
STRONGER STORMS MAY PRODUCE GUSTY AND ERRATIC WINDS...SMALL HAIL
AND HEAVY RAIN WITH BRIEF MVFR VISIBILITY AND CEILING RESTRICTIONS.
OTHERWISE...VFR CONDITIONS WILL PREVAIL.


&&

.FIRE WEATHER...
ISSUED AT 220 PM MDT SUN MAY 31 2015

GREEN-UP CONDITIONS ARE EXPECTED TO PERSIST DURING THE REMAINDER
OF THE WEEK. THERE WILL SCATTERED AREAS OF AFTERNOON AND EVENING
SHOWERS AND THUNDERSTORMS...ESPECIALLY ALONG AND EAST OF THE
LARAMIE RANGE THROUGH THE WEEK. THE EXCEPTION WILL BE ON TUESDAY
WHEN DRY AND WARMER CONDITIONS ARE EXPECTED WITH AFTERNOON HIGHS
IN THE 80S EAST OF THE LARAMIE RANGE DURING THE AFTERNOON.

&&

.HYDROLOGY...
ISSUED AT 204 PM MDT SUN MAY 31 2015

NO SIGNIFICANT CHANGES TO THIS MORNING`S FLOOD FORECASTS FOR THE
LOWER NORTH PLATTE RIVER. HENRY NE WILL HOLD STEADY NEAR 5.5 FEET
FOR THE NEXT FEW DAYS BEFORE FALLING BELOW FLOOD STAGE. MITCHELL
NE WILL REMAIN STEADY NEAR 8.7 FEET FOR THE NEXT FEW DAYS BEFORE
FALLING TO MINOR FLOOD STAGE. MINATARE NE WAS ESTIMATED NEAR 7.5
FEET DUE TO A GAGE PROBLEM AND WILL SLOWLY FALL BELOW FLOOD STAGE
BY MONDAY MORNING.

ALONG THE LARAMIE RIVER...LARAMIE`S STAGE WILL ABOVE FLOOD STAGE
OF 8 FEET WEDNESDAY MORNING AND WILL CREST NEAR 8.9 FEET FRIDAY
AS SNOWMELT RUNOFF EMPTIES INTO THE HEADWATERS OF THE RIVER. NEAR
FORT LARAMIE...THE STAGE WILL REMAIN STEADY NEAR 7.8 FEET THROUGH
MONDAY MORNING THEN FALL BELOW FLOOD STAGE SATURDAY.

ONGOING SNOWMELT ABOVE 9000 FT WITH HIGH TEMPERATURES IN THE MID
50S TO MID 60S WILL RESULT IN RISES TO BANKFULL ALONG THE UPPER
NORTH PLATTE AT SARATOGA.

ADDITIONAL RUNOFF FROM AFTERNOON AND EVENING CONVECTION MAY RESULT
IN MINOR RISES ALONG THE LARAMIE AND LOWER NORTH PLATTE RIVERS
THIS WEEK.

&&

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

$$

UPDATE...REC
SHORT TERM...REC
LONG TERM...MAJ
AVIATION...MAJ/CLH
FIRE WEATHER...REC
HYDROLOGY...MAJ



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.