Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 020828
AFDGLD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
228 AM MDT SAT MAY 2 2015

.UPDATE...
ISSUED AT 540 PM MDT FRI MAY 1 2015

UPDATE TO GOING FORECAST TO ACCOUNT FOR VEIL OF MID/HIGH CLOUDS
CURRENTLY OVER THE AREA. ALL ACTIVITY EMANATING FROM CONVECTION
OFF OVER CENTRAL COLORADO. TREND IS TO CONTINUE EASTWARD THRU THE
EVENING HOURS BEFORE DECREASING AFTER MIDNIGHT. HAVE GONE WITH
CLOUDY BECOMING PARTLY CLOUDY LATE FOR THE CWA. REST OF FORECAST
IS ON TRACK AT THIS TIME. CONVECTION OVER CENTRAL COLORADO IS
FINALLY EDGING INTO PORTIONS OF EASTERN COLORADO...SO WILL LEAVE
CURRENT POPS FOR TRW/RW IN PLACE.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH SATURDAY)
ISSUED AT 150 PM MDT FRI MAY 1 2015

EARLY AFTERNOON WV IMAGERY AND RAP H5 ANALYSIS SHOWS BROAD RIDGE IN
PLACE ACROSS THE SOUTHERN PLAINS WITH WESTERLY FLOW EXTENDING
FROM THE GREAT BASIN ACROSS THE CENTRAL ROCKIES AND INTO THE
CENTRAL PLAINS. A WEAK SHORTWAVE H5/H7 TROUGH IS IN THE PROCESS OF
ROTATING THROUGH THE MEAN FLOW ACROSS THE CENTRAL ROCKIES WITH
SHOWER/THUNDERSTORM DEVELOPMENT APPARENT ON UPSTREAM RADARS MOVING
EAST OFF THE HIGHER TERRAIN. AT THE SURFACE LOW PRESSURE IS IN
PLACE ACROSS THE CWA WITH A STATIONARY FRONT ALONG THE
SOUTHEASTERN CORNER OF THE CWA EXTENDING SOUTH IN SOUTHEAST
COLORADO.

THIS AFTERNOON-TONIGHT...FOCUS CONTINUES TO BE ON POTENTIAL FOR
THUNDERSTORMS DEVELOPING OVER THE CWA OR SPREADING EAST INTO THE
CWA AS SHORTWAVE MOVES THROUGH THE REGION. WITH FRONT IN PLACE AND
AIR MASS DESTABILIZING THERE IS SOME CONCERN THAT ISOLATED
THUNDERSTORMS COULD DEVELOP AHEAD OF MAIN SHORTWAVE. HIGH CINH
VALUES CURRENTLY IN PLACE ARE INHIBITING CONVECTION CURRENTLY OVER
THE CWA DESPITE INCREASING INSTABILITY. AS SHORTWAVE MOVES EAST
IT APPEARS THE CAP SHOULD WEAKEN ALLOWING FOR INCREASING CHANCES
FROM THE WEST TO THE EAST. BEST PRECIP SIGNAL FROM RAP/HRRR
CONTINUES TO BE IN THE SOUTHWEST PART OF THE CWA. 12Z GUIDANCE WAS
RUNNING HIGH REGARDING CAPE VALUES MOST OF THE DAY...THOUGH AS
SKIES HAVE CLEARED THE LATEST RAP ANALYSIS DOES SHOW 500-1000 KG/J
ML CAPE DEVELOPING OVER THE REGION. SHEER IS NOT PARTICULARLY
IMPRESSIVE AND AT THIS POINT SEVERE THREAT SEEMS TO BE LIMITED.
ANY SHOWER/THUNDERSTORM ACTIVITY SHOULD QUICKLY DISSIPATE OR
TRANSITION EAST OF THE CWA THROUGH LATE THIS EVENING AS A SHARP
AREA OF SUBSIDENCE MOVES IN BEHIND EXITING SHORTWAVE.

SATURDAY...VERY GOOD WAA IS ADVERTISED AND WITH CLEARING SKIES
DURING THE FIRST PART OF THE DAY HIGHS SHOULD REACH THE 80S ACROSS
THE CWA...POSSIBLY IN THE MID/UPPER 80S IN THE EAST. THE NEXT
SHORTWAVE IS SHOWN TO APPROACH THE REGION FROM THE CENTRAL ROCKIES
LATE AFTERNOON WITH THUNDERSTORM INITIATION NEAR SURFACE TROUGH
ALONG CO/KS BORDER POSSIBLE AFTER 21Z...OTHERWISE BETTER CHANCES
ARRIVE LATER IN THE EVENING. MODELS ARE SHOWING VERY UNSTABLE AIR
BUILDING OVER THE REGION WITH NAM ADVERTISING 1500-2500 J/KG OF ML
CAPE BY LATE AFTERNOON. SHEER IS A LITTLE BETTER THAN TODAY WITH
EFFECTIVE SHEER IN EXCESS OF 35KT. WITH THIS IN MIND ANY
THUNDERSTORMS THAT DEVELOP LATE TUESDAY AFTERNOON COULD
POTENTIALLY ORGANIZE AND BECOME SEVERE. WITH MINIMAL LOW LEVEL
SHEER LARGE HAIL/DAMAGING WIND CONTINUE TO BE MAIN CONCERNS.

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 226 AM MDT SAT MAY 2 2015

THE LONG TERM FORECAST PERIODS BEGINS WITH AN UPPER LEVEL SHORTWAVE
TROUGH THAT TAKES A NEGATIVE TILT INTO THE HIGH PLAINS
REGION...WHICH WILL BRING CHANCES FOR SHOWERS AND THUNDERSTORMS
TUESDAY.  ALTHOUGH A NEGATIVE TILT USUALLY SIGNIFIES STEEP LAPSE
RATES ALOFT...IN THIS CASE THE LAPSE RATES ARE NOT TOO IMPRESSIVE
WITH VERY LITTLE CAPE IN THE PROFILE. BETWEEN 200 AND 500 J/KG OF
CAPE IS PRESENT ACROSS THE AREA TUESDAY AFTERNOON AND EVENING...BUT
THAT IS ENOUGH WITH VERY SATURATED FORECAST SOUNDINGS TO PRODUCE
EFFICIENT RAINFALL.  STRONG SOUTHERLY FLOW THROUGHOUT THE ENTIRE
ATMOSPHERIC PROFILE WILL ADVECT MOIST GULF AIR INTO THE REGION WITH
PRECIPITABLE WATER AMOUNTS ACROSS THE AREA GREATER THAN ONE
INCH...WHICH IS IN THE 99TH PERCENTILE BASED ON CLIMATOLOGY.
THEREFORE...INCREASED POP AND QPF VALUES IN THE FORECAST FOR THIS
PERIOD WITH THE EXPECTATION OF WIDESPREAD MODERATE RAINFALL...WITH
LOCALLY HEAVY AMOUNTS.

IN THE EARLY MORNING HOURS WEDNESDAY...GFS SOUNDINGS INDICATE AN
INTRUSION OF DRY MID LEVEL AIR...WHICH WILL INCREASE CAPE VALUES IN
THE PROFILE HEADING INTO WEDNESDAY AFTERNOON BETWEEN 1000 AND 1800
J/KG....WHICH COULD RESULT IN SOME STRONGER THUNDERSTORMS.  SEVERE
POTENTIAL DOES NOT LOOK STRONG AT THIS POINT WITH WEAK SURFACE
FORCING...MARGINAL SPEED AND DIRECTIONAL SHEAR...AND DISAGREEMENT IN
MODEL FORECASTS REGARDING JET POSITION.

ALTHOUGH MODELS DISAGREE SLIGHTLY TO THE UPPER LEVEL TROUGH
POSITION...TIMING AND PATTERN GENERALLY LINE UP ON THURSDAY
AFTERNOON WITH THE UPPER TROUGH GETTING PINCHED OFF FROM THE MAIN
FLOW AND BECOMING CUT OFF OVER THE WESTERN THIRD OF THE CONUS.
BECAUSE THE LOW WILL BECOME REMOVED FROM THE MAIN UPPER JET
FLOW...THE FEATURE WILL SPIN SLOWLY EASTWARD OVER THE HIGH PLAINS
REGION PROVIDING CHANCES FOR SHOWERS AND THUNDERSTORMS THURSDAY
NIGHT THROUGH FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1115 PM MDT FRI MAY 1 2015

KGLD...VFR THROUGH THE PERIOD. SOUTHWEST WINDS 5-10KTS AT TAF
ISSUANCE EXPECTED TO BACK TO THE SOUTH AT SIMILAR SPEEDS AROUND
19Z THEN SOUTHWEST NEAR 10KTS FROM 02Z THROUGH THE REST OF THE TAF
PERIOD. THUNDERSTORMS ARE POSSIBLE AROUND OR OVER THE TERMINAL
AFTER 02Z THUS VCTS WORDING.

KMCK...VFR THROUGH THE PERIOD. LIGHT SOUTHWEST WIND AT TAF
ISSUANCE EXPECTED THROUGH THE TAF PERIOD. MAY SEE A FEW SHOWERS
FROM TAF ISSUANCE THROUGH 07Z AND VARIABLE WINDS GUSTING 20KTS OR
SO POSSIBLE. OTHERWISE...NO PRECIPITATION EXPECTED.


&&

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

$$

UPDATE...JN
SHORT TERM...DR
LONG TERM...MK
AVIATION...99



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