Area Forecast Discussion
Issued by NWS Cheyenne, WY

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000
FXUS65 KCYS 231746
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1146 AM MDT SAT MAY 23 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 400 AM MDT SAT MAY 23 2015

TODAY...AREAS OF FOG CONTINUE ACROSS MANY LOCATIONS VIA OBSERVATIONS
AND LOOKING AT WEBCAMS...SO HAVE CONTINUED THROUGH 9 AM. VISIBILITIES
MAY BE SLOWLY IMPROVING OVER THE I-80 SUMMIT LOOKING AT WEBCAMS.

CHANCES FOR SHOWERS INCREASE THIS MORNING...AND ESPECIALLY THIS
AFTERNOON AS THE NEXT SHORTWAVE TROUGH MOVES OVERHEAD NEAR PEAK
HEATING.

FOR THIS AFTERNOON...IMPRESSIVE 850 MB THETA-E RIDGE AXIS EXTENDS
FROM NORTHEAST COLORADO AND SOUTHEAST WYOMING. THE COMBINATION OF
DECENT SHEAR AND MODERATE INSTABILITY ALONG WITH ADEQUATE MOISTURE
TO FUEL THE THUNDERSTORMS. ALTHOUGH SPC HAS A SLIGHT RISK OF SEVERE
THUNDERSTORMS OVER NORTHEAST COLORADO...WE MAY SEE A FEW STRONG TO
SEVERE STORMS OVER OUR SOUTHEAST COUNTIES...IF THERE ARE A FEW BREAKS
IN THE LOW CLOUD STRATUS.

TONIGHT...UPPER TROUGH ALOFT AND A WAVE MOVE ACROSS OUR COUNTIES...
SPARKING ANOTHER WIDESPREAD SHOWER EVENT ALONG WITH AREAS OF FOG.

SUNDAY...MORE SHOWERS AND A FEW THUNDERSTORMS ON TAP AS THE UPPER
TROUGH MOVES OVERHEAD AND INSTABILITY SHOWERS BECOME EVEN MORE
PRONOUNCED. SHEAR AND INSTABILITY WILL LESSEN...THEN WITH NEIGHBORLY
AGREEMENT...PRESENTING A LESSENING OF STRONG THUNDERSTORMS IN THE
AFTERNOON.

SUNDAY NIGHT/MONDAY...FLOW ALOFT BECOMES NORTHWEST AND WITH ADEQUATE
LOW AND MID LEVEL MOISTURE PER PROGS...DAYTIME HEATING...WILL SEE
SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS IN THE
AFTERNOON. STORM STRENGTH SHOULD BE MINIMAL BASED ON CONVECTIVE
PARAMETERS.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 400 AM MDT SAT MAY 23 2015

ONLY SUBTLE DIFFERENCES WERE GLEANED FROM THE MEDIUM RANGE MODELS
COMPARED TO PREVIOUS RUNS. TROUGH RESPONSIBLE FOR THIS WEEKENDS
INCLEMENT WEATHER EXITS TOWARD THE UPPER MIDWEST...REPLACED BY A
SHORT WAVE RIDGE TUESDAY. SHOWER COVERAGE WILL DECREASE MONDAY
NIGHT...WITH A RETURN TO A MORE DIURNAL CONVECTIVE PATTERN TUESDAY
AS TEMPERATURES WARM. RIDGE BROADENS OVER THE GREAT PLAINS WITH A
TROUGH EJECTING EAST FROM CA TOWARD THE FOUR CORNERS BY THE END OF
THE WEEK. SURFACE PRESSURE PATTERN WILL BE WEAK WITH MAINLY LIGHT
AND VARIABLE WINDS. SHOWER/TSTORM COVERAGE FOR THE REMAINDER OF
THE WEEK WILL PRIMARILY BE SCATTERED DURING THE DAY AND ISOLATED
AT NIGHT. NOT LOOKING AT APPRECIABLE QPF BY ANY STRETCH. TEMPERATURES
WILL AVERAGE CLOSER TO SEASONAL NORMALS MID WEEK THEN COOL SOMEWHAT
FOR THE END OF THE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1138 AM MDT SAT MAY 23 2015

WYOMING TERMINALS...SHOWERS AND THUNDERSTORMS WILL BECOME MORE
WIDESPREAD THIS AFTERNOON WITH MVFR CIGS PREVAILING. BRIEF IFR
VSBYS COULD OCCUR BENEATH HEAVIER PCPN CORES ALONG WITH GUSTY
WINDS. STRATIFORM RAIN IS EXPECTED AFTER 02Z TONIGHT. IFR/LIFR
CONDITIONS ARE LIKELY THROUGH 12-15Z SUN.

NEBRASKA TERMINALS...WIDESPREAD IFR/LIFR CIGS/VSBYS WILL PERSIST
THROUGH MUCH OF THE TAF PERIOD. CONDITIONS COULD IMPROVE BRIEFLY
BY MID TO LATE AFTERNOON...BUT SHOWERS AND STRATIFORM RAIN WILL
EXPAND IN COVERAGE DURING THE LATE AFTN AND EVE. THE POOR FLYING
CONDITIONS ARE EXPECTED TO PERSIST THROUGH 12-15Z SUN.

&&

.FIRE WEATHER...
ISSUED AT 243 AM MDT SAT MAY 23 2015

MINIMAL ISSUES DUE TO WET GROUND AND PROGGED HUMIDITIES AND WINDS.

&&

.HYDROLOGY...
ISSUED AT 300 AM MDT SAT MAY 23 2015

WATER RELEASES FROM UPSTREAM GRAYROCKS RESERVOIR AND RUNOFF FROM
RAINFALL WILL KEEP THE LARAMIE RIVER NEAR FORT LARAMIE AROUND 7.5
FEET THROUGH THE WEEKEND. HIGH WATER LEVELS WILL CONTINUE AT
LARAMIE...CRESTING JUST BELOW FLOOD STAGE EARLY NEXT WEEK. SHOWER
COVERAGE WILL DECREASE NEXT WEEK...RETURNING TO A TYPICAL SCATTERED
DIURNAL PATTERN.

&&

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

$$

SHORT TERM...RUBIN
LONG TERM...JAMSKI
AVIATION...CLH
FIRE WEATHER...RUBIN
HYDROLOGY...JAMSKI



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