Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 251741
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1141 AM MDT SAT JUL 25 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 315 AM MDT SAT JUL 25 2015

WATER VAPOR IMAGERY SHOWED A STATIONARY UPPER RIDGE OVER THE
SOUTH CENTRAL CONUS WITH ACTIVE WESTERLY FLOW OVER THE NORTH
CENTRAL CONUS. SUBTROPICAL MOISTURE AND WEAK WAVES CIRCULATING
CLOCKWISE AROUND THE UPPER HIGH AIDED IN SEVERAL CLUSTERS OF
DEEP CONVECTION FROM THE CENTRAL PLAINS INTO THE LOWER/MID MS
VALLEY. A COMPLEX OF TSTORMS DEVELOPED ACROSS NORTHEAST WY
ASSOCIATED WITH THE LEFT FRONT QUADRANT OF UPPER JET STREAK.
THIS COMPLEX WILL CONTINUE TO TRACK EAST-NORTHEAST ACROSS
NORTHWEST SD OVERNIGHT. SURFACE ANALYSIS DEPICTED A WAVY FRONT
FROM A LOW IN NORTH CENTRAL IA ACROSS SOUTHERN NE...NORTHWEST KS
AND EAST CENTRAL CO THEN CURVING NORTHWEST INTO EASTERN WY. BACK
EDGE OF CIRRUS WAS MOVING THROUGH WESTERN NE LEAVING MOSTLY CLEAR
SKIES TO THE WEST.

THE LARGE SCALE PATTERN WE`VE BEEN ACCUSTOMED TO THE PAST SEVERAL
DAYS WILL CONTINUE WITH A CENTRAL CONUS RIDGE FLANKED BY TROUGHS
TO THE WEST AND EAST. ISOLATED CONVECTION DEVELOPED OVER THE
PLAINS LATE FRIDAY ALONG A INSTABILITY GRADIENT. THE GRADIENT
WILL SHIFT EAST OF THE CWA TODAY...HOWEVER JET ENERGY COMBINED
WITH LINGERING MID LEVEL MOISTURE MAY TRIGGER ISOLATED AFTERNOON
CONVECTION ACROSS THE HIGH PLAINS. THE MAJORITY OF THE MODELS
MAINTAIN DRY CONDITIONS...HOWEVER THE HRRR GENERATES A 20-30
PERCENT COVERAGE OF CONVECTION. NOT TOTALLY BUYING THE HRRR...WITH
10-15 PERCENT POPS FORECAST ATTM. 700MB TEMPERATURES PEAK NEAR 15C
TODAY WITH AFTERNOON HIGHS IN THE UPPER 80S-MID 90S FOR THE
PLAINS. IT WILL BE BREEZY WEST OF THE LARAMIE RANGE WITH SOUTHWEST
WINDS GUSTING TO NEAR 25 MPH.

HIGH TEMPERATURES SUNDAY AND MONDAY WILL BE 3-5 DEGREES WARMER
WITH 700MB TEMPERATURES PEAKING 16-17C. 90S WILL PREVAIL EAST
OF THE LARAMIE RANGE BOTH DAYS. MONDAY AFTERNOON WILL BE WARMEST
OF THE TWO DAYS...WITH A FEW LOCATIONS IN THE WESTERN NE PANHANDLE
TOPPING OUT AT 100 DEGREES. LOW LEVEL THERMAL/INSTABILITY AXIS
WILL RESIDE EAST OF THE CWA...HOWEVER WITH THE POSITION OF THE
RIGHT REAR QUADRANT OF THE UPPER JET OVERHEAD...CANNOT RULE OUT
A FEW AFTERNOON/EARLY EVENING TSTORMS FOR THE HIGH PLAINS SUNDAY
AND MONDAY. THE PRESSURE GRADIENT AND INCREASING SOUTHWEST FLOW
ALOFT AHEAD OF AN APPROACHING TROUGH AND COLD FRONT MONDAY WILL
INDUCE WINDY CONDITIONS WEST OF THE LARAMIE RANGE WITH GUSTS
POSSIBLY EXCEEDING 40 MPH.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 230 AM MDT SAT JUL 25 2015

WEATHER CONDITIONS WILL REMAIN ON THE DRIER SIDE THROUGH THE
LONGER TERM FORECAST PERIOD. MONDAY NIGHT STARTS OFF WITH AN
UPPER LEVEL TROUGH OVER THE NORTHERN ROCKIES. DEPENDING ON THE
EXACT TRACK OF THE UPPER LEVEL LOW COULD SEE A FEW THUNDERSTORMS
OVER FAR NORTHERN AND/OR EASTERN PORTIONS OF THE FORECAST AREA
MONDAY EVENING. CURRENTLY THE GFS AND ECMWF KEEP THE MAIN ENERGY
NORTH OF THE FORECAST AREA.

A REINFORCING PUSH OF COOLER AIR EXPECTED TUESDAY AS THE MAIN
UPPER LEVEL TROUGH PUSHES EAST INTO THE PLAINS. TIMING OF THE COOL
PUSH SHOULD KEEP CHANCES FOR PRECIPITATION AT A MINIMUM OVER THE
FORECAST AREA WITH THUNDERSTORM ACTIVITY LIKELY DEVELOPING WELL
EAST INTO CENTRAL NEBRASKA AND SOUTH INTO COLORADO. HIGH
TEMPERATURES TUESDAY SHOULD RANGE FROM THE LOWER 70S WEST TO
LOW-MID 80S INTO THE PLAINS.

MILD TEMPERATURES SHOULD CONTINUE WEDNESDAY WITH SOUTHEAST LOW
LEVEL FLOW IN PLACE OVER THE PLAINS. WEDNESDAY ALSO LOOKS TO BE ON
THE DRY SIDE WITH VERY MINIMAL CHANCES FOR PRECIPITATION...
ESPECIALLY WITH THE FORECAST AREA UNDER THE SUBSIDENCE SIDE OF THE
REAR UPPER LEVEL JET. ALSO LOOKING AT WESTERLY FLOW ALOFT
DEVELOPING WITH ZONAL FLOW IN PLACE OVER THE WESTERN CONUS.

WARMING TREND FOR LATTER PORTIONS OF NEXT WEEK WITH RIDGING OVER
THE WESTERN CONUS AND WEST TO NORTHWEST FLOW OVER THE FORECAST
AREA. HIGH TEMPERATURES SHOULD WARM INTO THE LOW 80S WEST TO
AROUND 90 INTO THE PLAINS THURSDAY AND SLIGHTLY WARMER FRIDAY.
EXPECTING VERY ISOLATED AFTERNOON THUNDERSTORMS ACTIVITY BUT
OVERALL CHANCES FOR WETTING RAIN WILL BE VERY LOW WITH
THUNDERSTORM COVERAGE LIKELY LESS THAN 10 PERCENT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1139 AM MDT SAT JUL 25 2015

VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD. WIDESPREAD
GUSTY WINDS WILL DEVELOP ALONG AND WEST OF THE LARAMIE RANGE BY
18Z SUN.

&&

.FIRE WEATHER...
ISSUED AT 222 AM MDT SAT JUL 25 2015

WARM AND MAINLY DRY CONDITIONS WILL CONTINUE FOR THE DISTRICTS
THROUGH MONDAY BEFORE THE PASSAGE OF A COLD FRONT TUESDAY. NEAR-
CRITICAL WINDS AND HUMIDITIES FOR PORTIONS OF EAST CENTRAL AND
SOUTH CENTRAL WYOMING CAN BE EXPECTED THIS WEEKEND. THE BEST
CHANCE FOR WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS WILL BEGIN
MONDAY MORNING AS WINDS ALOFT INCREASE FOLLOWING POOR OVERNIGHT
HUMIDITY RECOVERIES. SOUTHWEST WINDS MAY GUST OVER 40 MPH WEST OF
THE LARAMIE RANGE MONDAY WITH AFTERNOON HUMIDITIES FALLING INTO
THE SINGLE DIGITS TO LOW TEENS PERCENT. COOLER TEMPERATURES AND
SLIGHTLY HIGHER HUMIDITIES WILL PREVAIL TUESDAY.

&&

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

$$

SHORT TERM...MAJ
LONG TERM...SML
AVIATION...CLH
FIRE WEATHER...MAJ



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