Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 221805
AFDGLD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
1205 PM MDT FRI AUG 22 2014

.UPDATE...
ISSUED AT 1158 AM MDT FRI AUG 22 2014

OBSERVATIONAL AND MODEL DATA SUPPORT HAVING NORTHWARD MOVING FRONT
FURTHER SOUTH. SURFACE LOW OVER SOUTHEAST COLORADO HAS MOVED MUCH
AND GOING BY THE WINDS TO THE NORTH OF THE FRONT...THE LOW HAS
INTENSIFIED. OUTFLOW FROM THUNDERSTORMS HAS ALSO HELPED IN KEEPING
THIS BOUNDARY FURTHER SOUTH. MODELS NOT REALLY DEVELOPING ANYTHING
ALONG THE FRONT. THEY WANT TO INCREASE THE ACTIVITY THAT HAS BEEN
OVER EASTERN COLORADO ALL DAY AND BRING IT WEST.

COMBINATION OF THE PERSISTENT AREA OF COLORADO
CONVECTION...POSITION OF OUTFLOW BOUNDARY...AND CURRENT FRONTAL
POSITION LED ME TO INCREASE POPS MORE/FURTHER SOUTH. WITH CURRENT
DEVELOPMENT MAY NEED TO INCREASE MORE. NAM...RAP AND ECMWF APPEAR
TO BE CATCHING THE POSITION OF THE BOUNDARY THE BEST. MADE OTHER
ADJUSTMENTS TO HOURLY GRIDS BASED ON LATEST TRENDS.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 355 AM MDT FRI AUG 22 2014

THE MAIN FORECAST CONCERN IN THE SHORT TERM IS THE POSSIBILITY OF
SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS
REGION LATE THIS AFTERNOON AND EVENING.

THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN OF
COLORADO AND MOVE EASTWARD DURING THE AFTERNOON MAINLY ALONG AND
NORTH OF A STATIONARY SURFACE BOUNDARY THAT LIFTS NORTHWARD
THROUGH THE FORECAST AREA AS AN UPPER LEVEL SHORT WAVE TROUGH
LIFTS THROUGH THE 4-CORNERS REGION AND A SURFACE LOW CENTER
DEEPENS OVER THE SOUTHEAST COLORADO/SOUTHWEST KANSAS BORDER AREA
BY 00Z AND LIFTS NORTH INTO NORTHWEST TO NORTHCENTRAL KANSAS BY
06Z. BY 00Z THIS BOUNDARY IS EXPECTED TO STRETCH FROM LIMON
COLORADO TO ATWOOD AND NORTON KANSAS AND WILL CONTINUE TO LIFT
NORTHWARD OVERNIGHT. SOME OF THE STORMS ARE EXPECTED TO BECOME
SEVERE WITH AN UNSTABLE AIRMASS AND FAVORABLE SHEAR PROFILES
INDICATING THE DEVELOPMENT OF SUPERCELL STORMS WITH LARGE HAIL AND
A FEW TORNADOES POSSIBLE IN THE VICINITY OF THE KANSAS/NEBRASKA
BORDER AREA.

ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED ACROSS THE CENTRAL HIGH
PLAINS REGION ON SATURDAY AFTERNOON AND EVENING AS A SECONDARY
UPPER LOW CENTER ROTATES THROUGH THE MAIN UPPER TROUGH OVER THE
WESTERN UNITED STATES AND ANOTHER SURFACE LOW LIFTS NORTHEASTWARD
ACROSS THE FORECAST AREA OVERNIGHT SATURDAY NIGHT.

TEMPERATURES WILL BE SOMEWHAT COOLER ON SUNDAY WITH NORTHERLY
SURFACE FLOW ON THE BACK SIDE OF THE SURFACE TROUGH EXITING THE
REGION. ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN
SUNDAY AFTERNOON AND EVENING AS ADDITIONAL WEAK DISTURBANCES LIFT
OUT ACROSS THE CENTRAL HIGH PLAINS REGION IN THE SOUTHWEST FLOW
ALOFT.

.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 355 AM MDT FRI AUG 22 2014

FOR THE LAST WEEK OF AUGUST THE OVERALL PATTERN WILL SUPPORT A FEW
CHANCES FOR RAIN WITH NEAR TO SLIGHT BELOW NORMAL TEMPERATURES. ON
THE SYNOPTIC SCALE AN UPPER HIGH ACROSS THE LOWER MISSISSIPPI AND
TENNESSEE VALLEY REGIONS WILL PERSIST THROUGH THE EARLY PART OF THE
WEEK WHILE A LONGWAVE TROUGH MOVES EAST ACROSS THE GREAT BASIN
REGION OF WESTERN CONUS. MODEL SPREAD IS FAIRLY LARGE TO START THE
EXTENDED PERIOD....AND WHILE THE SET UP DEFINITELY LOOKS FAVORABLE
FOR A NUMBER PRECIP EVENTS...THE DIFFERENCES THIS FAR OUT MAKE IT
DIFFICULT TO PIN DOWN TIMING.

BRIEFLY ON THE MODEL DIFFERENCES...THE GFS SOLUTION IS FAIRLY
PROGRESSIVE BRINGING THE LONGWAVE TROUGH ACROSS THE CENTRAL HIGH
PLAINS LATE TUESDAY...WITH NORTHWESTERLY FLOW LINGERING ON THROUGH
THE END OF THE WEEK. THE GEFS ENSEMBLE MEAN IS A BIT
SLOWER...DELAYING THE TROUGH UNTIL WEDNESDAY OR SO. ECMWF IS MUCH
SLOWER...TAKING TIME TO DEVELOP A DEEPER RIDGE AXIS OVER THE
SOUTHWEST AND INTO THE FOUR CORNERS REGION BY LATE WEDNESDAY. WHILE
DELAYING THE TROUGH...THIS PATTERN IS ACTUALLY VERY FAVORABLE FOR A
FEW DAYS OF GOOD RAINFALL AS THIS WOULD ALLOW A NUMBER OF WEAK
SHORTWAVE IMPULSES TO MOVE UP ACROSS THE SOUTHERN AND CENTRAL HIGH
PLAINS AS WELL AS VERY MOIST AIR. FINALLY...THE CANADIAN IS SIMILAR
TO THE ECMWF BUT EVEN SLOWER...WITH THE BEST SET-UP FOR RAINFALL
LATE TUESDAY INTO WEDNESDAY.

MONDAY...TYPICAL AUGUST DAY WITH SCATTERED AFTERNOON CONVECTION.
GUIDANCE SUPPORTS 1000-1500 J/KG SBCAPE WITH GOOD LARGE-SCALE
LIFTING IN PLACE AND AN EAST-WEST ORIENTED STATIONARY FRONT ACROSS
NORTHWEST KANSAS AND NORTHEAST COLORADO. WIND PROFILES SUPPORT
SUPERCELL DEVELOPMENT WITH 35-45 KTS OF 0-6KM SHEAR...SO WOULD
EXPECT SOME STRONG TO SEVERE THUNDERSTORMS PRODUCING LARGE
HAIL...DAMAGING WINDS...AND POSSIBLY A TORNADO. TEMPS IN THE MID TO
UPPER 80S.

TUESDAY/WEDNESDAY...AS DISCUSSED IN THE PARAGRAPH ABOUT MODEL
DIFFERENCES THERE APPEARS TO BE A GOOD SET UP FOR HEAVY RAIN
SOMETIME DURING THIS TIME PERIOD. AM FAIRLY CERTAIN THE ENTIRE CWA
WILL SEE RAINFALL DURING THIS PERIOD...WITH MANY RECEIVING OVER A
HALF INCH OVER THE COURSE OF THE EVENT. AT THIS POINT THE LATEST
GUIDANCE IS AGREEING ON LATE TUESDAY INTO EARLY WEDNESDAY FOR THE
BEST CHANCE. TEMPS WILL BE COOLER AS STATIONARY FRONT FROM MONDAY
TRANSITIONS TO A COLD FRONT AND MOVES SOUTH AS A COOLER AIRMASS
MOVES IN FROM THE NORTH...HIGHS IN THE LOW 80S.

THURSDAY AND BEYOND...WHILE MAJOR MODEL DIFFERENCES EXIST AT THIS
TIME FRAME BELIEVE PRECIP CHANCES WILL BE LOW AND TEMPS SEASONABLE
/MID TO UPPER 80S/ LATE IN THE WEEK AS AN UPPER LEVEL RIDGE
EVENTUALLY MOVES ACROSS THE REGION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1158 AM MDT FRI AUG 22 2014

THUNDERSTORMS ARE EXPECTED TO AFFECT BOTH TAF SITES WITH DEVELOPMENT
ALREADY UNDERWAY. STORMS SHOULD AFFECT KGLD FIRST. MVFR AND
POSSIBLY IFR CONDITIONS COULD DEVELOP AT BOTH SITES BEFORE
ACTIVITY ENDS AROUND 06Z. DID NOT INCLUDE ANY FOG OR STRATUS AFTER
THE STORMS AT THIS TIME SINCE WESTERLY WINDS TEND TO SCOUR THE
MOISTURE OUT.

&&

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

$$

UPDATE...BULLER
SHORT TERM...LOCKHART
LONG TERM...JJM
AVIATION...BULLER


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