Area Forecast Discussion
Issued by NWS Goodland, KS

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000
FXUS63 KGLD 050009
AFDGLD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
609 PM MDT MON MAY 4 2015

.UPDATE...
ISSUED AT 555 PM MDT MON MAY 4 2015

CURRENT RADAR SHOWS THE TWO SEPERATE WAVES OF RAINFALL MERGING
INTO ONE AS OUTFLOW BOUNDARIES FROM THE SOUTHERN WAVE OVER
SOUTHWEST KANSAS MERGE WITH THE NEARLY STATIONARY STORMS OVER THE
FRONT. CURRENT FORECAST SEEMS TO HAVE THE GENERAL TREND OF STORM
DEVELOPMENT TONIGHT HANDLED FAIRLY WELL. GENERALLY LOOKS LIKE
LOCATIONS WEST OF HIGHWAY 25 WILL HAVE THE BEST SHOT AT PROLONGED
RAINFALL TONIGHT AS TWO DIFFERENT WAVES MOVE OVER THAT PART OF THE
AREA. DUE TO THE SLOW MOVEMENT OF THE STORMS...LESS THAN 20
MPH...FLASH FLOODING WILL BE A CONCERN THROUGH THE NIGHT.

REGARDING SEVERE WEATHER...INSTABILITY DECLINES DURING THE
EARLY EVENING BUT THEN RETURNS OVERNIGHT EAST OF HIGHWAY 83. THERE
STRONG TO POSSIBLY SEVERE STORMS ARE POSSIBLE...ALTHOUGH DEEP
LAYER SHEAR IS ONLY 25KTS WHICH IS BARELY ENOUGH TO SUPPORT
SUPERCELLS.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 220 PM MDT MON MAY 4 2015

EARLY AFTERNOON WV IMAGERY AND RAP UPPER LEVEL ANALYSIS SHOW
DEEPENING TROUGH OVER SOUTHERN CALIFORNIA WITH SW FLOW FROM THE GULF
OF ALASKA AND ACROSS THE CENTRAL/HIGH PLAINS. MOIST PLUME EXTENDS
FROM THE GREAT BASIN ACROSS THE OHIO RIVER VALLEY WITH ADDITIONAL
MOISTURE FEEDING IN THE PLAINS FROM THE GULF OF MEXICO. AT THE
SURFACE A STATIONARY FRONT EXTENDS FROM NORTHEAST KANSAS TO
SOUTHEAST COLORADO AND LIES JUST SOUTHEAST OF OUR CWA...WITH
BAROCLINIC ZONE EXTENDING NORTH INTO THE SE PART OF OUR CWA.
THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG THIS FRONTAL ZONE
TOWARDS THE SOUTHEAST PART OF OUR CWA.

THIS AFTERNOON-EVENING...ALONG THIS FRONTAL ZONE ANALYSIS INDICATES
ML CAPE VALUES RANGING FROM 1500 J/KG IN THE WARM SECTOR TO 500
J/KG IN OUR SE CWA. BULK SHEER IS APPROXIMATELY 30-35KT...SO
DEPENDING ON POSITION OF FRONT (CURRENTLY ADVERTISED TO SLIDE NORTH
INTO OUR SOUTHEAST)...THERE IS THE POTENTIAL FOR A FEW STRONGER
THUNDERSTORMS...POSSIBLY SEVERE WITH LARGE HAIL/DAMAGING WINDS MAIN
THREAT. IF FRONT WERE TO LIFT NORTH AS WARM FRONT WE COULD SEE
BETTER SB/ML CAPE AND THE POSSIBILITY FOR A FEW MORE ORGANIZED CELLS
IN THE SOUTHEAST. ANALYSIS ALSO INDICATES PWAT VALUES ALREADY IN
EXCESS OF 1" OVER OUR EAST. STORM MOTIONS WILL BE ROUGHLY
TANGENTIAL/PARALLEL THIS AFTERNOON BECOMING PERPENDICULAR TO FRONTAL
ZONE THIS EVENING. AS THIS TRANSITION OCCURS THERE IS THE
FOR BACKBUILDING OR TRAINING AS VERY MOIST/UNSTABLE AIR IN THE WARM
SECTOR FEEDS NORTH. THERE COULD BE A THREAT FOR FLASH FLOODING IF
THIS SCENARIO PLAYS OUT. EITHER WAY WITH VERY MOIST AIR MASS AND
INCREASING ELEVATED INSTABILITY...THUNDERSTORMS COULD BE VERY
EFFICIENT RAINFALL PRODUCERS.

TONIGHT-TUESDAY...UPSTREAM AREAS OF MID LEVEL VORTICITY WILL ROTATE
INTO THE CWA WITH INCREASING LIFT LATE THIS EVENING INTO THE
OVERNIGHT. AS TROUGH CONTINUES TO DEEPEN OVER THE SW US AND MOVE
EAST WE WILL CONTINUE TO SEE VERY GOOD FORCING/MOISTURE ROTATES
THROUGH THE REGION. LARGE SCALE Q VECTOR FIELDS INDICATED FORCING
INCREASING THROUGH THE NIGHT AND  OMEGA/MOISTURE
CONVERGENCE FIELDS SHOW SUPPORT FOR INCREASING COVERAGE/COMPLEX OF
SHOWERS THUNDERSTORMS. ELEVATED INSTABILITY TRANSITIONS NORTHWARD
AND WEAKENS...HOWEVER THERE IS ENOUGH TO KEEP THUNDER MENTION IN
PLACE THROUGH TUESDAY AFTERNOON. WHILE GUIDANCE IS IN AGREEMENT ON
GENERAL LARGE SCALE PATTERN THE MAIN DIFFERENCES ARE ON TIMING OF
POTENTIAL PERIODS OF HEAVIER PRECIP...WITH BEST PRECIP SIGNAL AND
MOISTURE PROFILES OVERLAPPING TUESDAY MORNING THROUGH TUESDAY
AFTERNOON ACROSS THE WESTERN 2/3 OF THE CWA (THOUGH ECMWF MIGHT BE A
LITTLE EAST). THERE WILL BE MODERATE/ELEVATED INSTABILITY IN PLACE
THROUGH THE DAY TUESDAY...SO STRONG TO SEVERE THUNDERSTORMS WILL
STILL BE POSSIBLE AGAIN...THOUGH SEVERE POTENTIAL MIGHT NOT BE AS
GOOD AS TODAY WITH WIDESPREAD SHOWERS AND STRATUS LIMITING SURFACE
BASED PARCELS AND ANY ACTIVITY LIKELY EMBEDDED WITH OTHER SHOWER
CLUSTERS.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 124 PM MDT MON MAY 4 2015

MAIN TROUGH AXIS WILL LIFT NORTHEAST ACROSS THE AREA TUESDAY NIGHT
WITH GOOD CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUING. AFTER
MIDNIGHT...GENERAL TREND WILL BE FOR A WEST TO EAST END OF THE
PRECIPITATION AS DRY SLOT WORKS IN BEHIND THE TROUGH. AFTER A LULL
WEDNESDAY MORNING...WRAPAROUND PRECIPITATION WILL MOVE IN FROM
COLORADO WEDNESDAY AFTERNOON AND BECOME WIDESPREAD WEDNESDAY
NIGHT. A COLD FRONT WILL ALSO MOVE THROUGH WEDNESDAY NIGHT WHICH
WILL PROVIDE A FOCUS FOR THUNDERSTORMS IN THE EVENING...BUT THE
POST FRONTAL ENVIRONMENT HAS ONLY LIMITED ELEVATED INSTABILITY AND
EXPECT ONLY ISOLATED THUNDERSTORMS THROUGH THURSDAY MORNING.
HOWEVER BY THURSDAY AFTERNOON SBCAPE INCREASES ONCE AGAIN AND A
COMBINATION OF MOIST LOW LEVEL UPSLOPE AND ANOTHER SHORTWAVE
TROUGH IN THE SOUTHWESTERLY FLOW ALOFT WILL RESULT IN THUNDERSTORM
DEVELOPMENT IN EASTERN COLORADO WHICH WILL MOVE INTO NORTHWEST
KANSAS AND SOUTHWEST NEBRASKA THURSDAY EVENING. SEVERE THREAT WILL
DEPEND ON HOW MUCH INSTABILITY CAN DEVELOP AFTER A CLOUDY
MORNING...BUT DEEP LAYER SHEAR WOULD BE SUPPORTIVE OF ORGANIZED
UPDRAFTS THROUGH EARLY EVENING BEFORE BOUNDARY LAYER DECOUPLES
WITH NOCTURNAL COOLING.

OVERALL PATTERN CHANGES LITTLE ON FRIDAY ALTHOUGH MODELS SHOWING
ONLY MINIMAL SBCAPE AVAILABLE SO SEVERE THREAT MAY NOT BE AS
GREAT. ANOTHER STRONG UPPER LOW WILL KICK OUT OF THE DESERT
SOUTHWEST ON SATURDAY WITH A NEGATIVE TILT AND PROVIDE THE
SYNOPTIC SCALE FORCING FOR THUNDERSTORMS. THE PATTERN SUGGESTS A
SEVERE THREAT WITH MODELS SHOWING DEEP LAYER SHEAR OF OVER 50KTS
AND SUFFICIENT INSTABILITY FOR SUPERCELLS. IF CURRENT TIMING
TRENDS CONTINUE WOULD EXPECT TO SEE A DRY SLOT SATURDAY NIGHT
FOLLOWED BY WRAPAROUND PRECIPITATION CHANCES ON SUNDAY.

THE PATTERN FINALLY CHANGES BY EARLY NEXT WEEK WITH SUBTLE
SHORTWAVE RIDGING IN A ZONAL FLOW WHICH WOULD TRANSLATE TO DRY
CONDITIONS AND SEASONABLE TEMPERATURES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 555 PM MDT MON MAY 4 2015

VFR TO LIFR CONDITIONS FOR THE TAFS. CHALLENGING SET OF TAFS DUE
TO TIMING OF THE DIFFERENT WAVES OF RAINFALL...THE CEILING
HEIGHTS AND VISIBILITY. IN GENERAL LOOKS LIKE KGLD WILL HAVE A
BETTER CHANCE FOR RECEIVING RAINFALL THAN KMCK...ESPECIALLY
PROLONGED RAINFALL. BASED TIMING OF THE STORMS FOR BOTH SITES BY
TRACKING THE SPEED OF THE CURRENT STORMS. IF STORM MOVEMENT
CHANGES THAT WILL AFFECT THE TIMING IN THE TAFS.  BASED ON
OBSERVATIONS AND MODEL SOUNDINGS...LOOKS LIKE THE SECOND WAVE OF
STORMS WILL CAUSE CIELINGS TO FALL. OVERNIGHT VISIBILITIES WILL
DECLINE SOME BUT THEN IMPROVE BY MID MORNING. HAVE VC FOR KMCK DUE
TO UNCERTAINTY THERE WILL STILL BE RAINFALL AT THE SITE DURING THE
MORNING.

&&

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

$$

UPDATE...JTL
SHORT TERM...DR
LONG TERM...024
AVIATION...JTL



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