Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 211713
AFDGLD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
1113 AM MDT SUN SEP 21 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 232 AM MDT SUN SEP 21 2014

A FEW STORMS DEVELOPED EARLY THIS MORNING IN SOUTHEAST COLORADO.
WAS CONCERNED THAT AN ISOLATED STORM MIGHT DEVELOP IN CHEYENNE
COUNTY COLORADO...BUT LATEST HIGH RESOLUTION MODELS KEEP
CONVECTION SOUTH OF THE AREA. WATER VAPOR SHOWS A GOOD PLUME OF
MOISTURE ACROSS EASTERN COLORADO AND WESTERN KANSAS.

SURFACE HIGH PRESSURE WILL MOVE ACROSS NEBRASKA AND CENTRAL KANSAS
TODAY. THIS WILL RESULT IN WEAK UPSLOPE FLOW ACROSS THE FORECAST
AREA. THE AIR MASS WILL CONTINUE TO DRY AT THE SURFACE TODAY WITH
DEW POINTS DROPPING INTO THE MID 40S. AS 500 MB RIDGE MOVES OVER
EASTERN COLORADO THIS AFTERNOON...WILL CONTINUE WITH A DRY
FORECAST. ALTHOUGH COLD AIR ADVECTION WILL WEAKEN THIS
AFTERNOON...HIGH TEMPERATURES WILL BE ABOUT 10 DEGREES COOLER
THAN YESTERDAY.

500 MB LOW WILL MOVE OVER THE NORTHERN ROCKIES TONIGHT WHICH WILL
FORCE MID LEVEL RIDGE OVER THE FORECAST AREA. CONVECTION WILL
DEVELOP OVER THE COLORADO FRONT RANGE...BUT THE CHANCES THAT STORMS
MOVE EAST ACROSS THE FORECAST AREA ARE LOW GIVEN LACK OF INSTABILITY
ACROSS THE EASTERN PLAINS.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 232 AM MDT SUN SEP 21 2014

MODELS ARE IN FAIR AGREEMENT THAT RAIN CHANCES WILL INCREASE MONDAY
AND MONDAY NIGHT. 500 MB LOW WILL MOVE OVER WYOMING BY MONDAY
AFTERNOON. LEE CYCLOGENESIS IS EXPECTED AFTER 18Z MONDAY WHICH
WILL STRENGTHEN SURFACE WINDS. WARM AIR ADVECTION AND DECENT LOW
LEVEL MOISTURE TRANSPORT WILL OCCUR ON SOUTH TRAJECTORIES.
FORECASTED MIXED LAYER CAPES ACROSS EASTERN COLORADO NEAR THE LEE
SIDE TROUGH WILL BE BETWEEN 500-1000 J/KG. LOW TO MID LAYER
Q-VECTOR CONVERGENCE IMPLIES GOOD UPWARD VERTICAL MOTION. SO WILL
CONTINUE WITH MODERATE TO HIGH POPS DURING THE AFTERNOON AND
EVENING. MODEL SOUNDINGS SHOW PRECIPITABLE WATER VALUES AROUND
1.25 INCHES AT GOODLAND...BUT HIGHER ACROSS EASTERN COLORADO.
NORTH AMERICAN ENSEMBLE FORECAST SYSTEM SHOWS PRECIPITABLE WATER
VALUES ABOUT THREE STANDARD DEVIATIONS HIGHER THAN NORMAL MONDAY
AFTERNOON...SO EXPECT SOME AREAS WILL GET PERIODS OF HEAVY RAIN.
WARM AIR ADVECTION WILL BE TEMPERED BY EXTENSIVE CLOUD COVER.

LOW LEVEL MOISTURE WILL INCREASE MONDAY NIGHT AND TUESDAY RESULTING
IN AN UNSTABLE AIR MASS BY TUESDAY AFTERNOON. MIXED LAYER CAPES BY
TUESDAY AFTERNOON ARE PROGGED TO RANGE FROM 1000 TO 1500 J/KG EAST
OF THE KANSAS/COLORADO BORDER. 500 MB TROUGH AXIS IS EXPECTED TO
MOVE ACROSS THE EASTERN HALF OF THE FORECAST AREA BETWEEN 18Z-00Z.
EXPECT 0-6KM SHEAR TO INCREASE DURING THE DAY REACHING 30-35
KNOTS BY THE AFTERNOON. WOULD NOT BE SURPRISED TO HAVE SOME SEVERE
STORMS TUESDAY AFTERNOON.

THE 500 MB RIDGE WILL BUILD OVER COLORADO LATE TUESDAY NIGHT. MOST
PRECIPITATION WILL ADVECT EAST OF THE AREA AFTER 06Z TUESDAY NIGHT
AS THE UPPER LEVEL TROUGH MOVES EAST.

THE SLOW MOVING UPPER LEVEL SHORTWAVE TROUGH WILL CONTINUE MOVING
EAST ACROSS THE PLAINS WEDNESDAY. MODELS HAVE BEEN FAIRLY
CONSISTENT THE LAST FEW RUNS WITH TIMING...SO FEEL COMFORTABLE
MAINTAINING A SLIGHT/LOW CHANCE POP EARLY WEDNESDAY ACROSS THE FAR
SOUTH AND EAST. CONFIDENCE HAS INCREASED SLIGHTLY FOR THURSDAY AND
FRIDAY WITH MEDIUM RANGE GUIDANCE GAINING MORE CONSISTENCY WITH
EACH RUN. DIFFERENCES IN THE POSITION OF RETROGRADING UPPER LOW
STILL EXIST THOUGH AND THIS HAS IMPLICATIONS FOR PRECIPITATION
CHANCES. THE PERSISTENT THEME FOR THE LAST FEW FORECASTS HAS BEEN
FOR CLIMATOLOGY POPS WHICH ARE SLIGHT CHANCE AT BEST. THIS HAS
BEEN MAINTAINED. PLUME OF DEEPER MOISTURE MOVES WEST WITH
RETROGRADING UPPER LOW AS SEEN IN FORECAST SOUNDINGS...AND THIS WOULD
POTENTIALLY SUPPORT HIGHER POPS ONCE AGREEMENT INCREASES.
PRECIPITABLE WATER STAYS BELOW 2 STANDARD DEVIATIONS BUT IS STILL
ABOVE CLIMATOLOGY. BY SATURDAY...UNCERTAINTY IS ABOVE AVERAGE. GFS
IS MORE PROGRESSIVE WITH WEST COAST TROUGH WHILE ECMWF IS MORE
AMPLIFIED AND CLOSED OFF AND KEEPS IT MUCH FURTHER WEST. EITHER
WAY INFLUENCES TO SENSIBLE WEATHER FROM THIS SYSTEM WOULD LIKELY
COME AFTER THE EXTENDED PERIOD. TEMPERATURES SHOULD BE CLOSE TO
NORMAL FOR MID/LATE SEPTEMBER THROUGH THE ENTIRE EXTENDED PERIOD
WITH NO SIGNIFICANT TEMPERATURE ADVECTION SCENARIOS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1111 AM MDT SUN SEP 21 2014

VFR EXPECTED AT BOTH KGLD AND KMCK THROUGH THE TAF PERIOD. SURFACE
HIGH PRESSURE CENTERED OVER THE NORTHERN PLAINS WILL RESULT IN
LIGHT EAST TO SOUTHEAST WINDS. OCCASIONAL MID AND HIGH CLOUDS
WILL SPILL OVER THE ROCKIES.

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

SHORT TERM...MENTZER
LONG TERM...BRB
AVIATION...024


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