Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 271719
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1219 PM CDT MON JUL 27 2015

...UPDATE TO AVIATION FORECAST DISCUSSION...

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT MON JUL 27 2015

REGIONAL RADARS SHOW A CLUSTER OF CONVECTION PERSISTING ACROSS
SOUTHWEST KS WHERE THE CONVERGENCE ON THE NOSE OF THE LOW LEVEL JET
APPEARS TO BE FOCUSED PER 88D PROFILER WINDS. THE 00Z TOP RAOB
SHOWED 700MB TEMPS OF ALMOST 13C AND THINK THE WARM TEMPS IN MID
LEVELS AND GOOD INHIBITION IS THE REASON WHY STORMS ARE STRUGGLING
TO MOVE FURTHER EAST INTO THE FORECAST AREA. ALOFT, WATER VAPOR
IMAGERY HAS THE CENTER OF THE UPPER RIDGE OVER THE TX PANHANDLE WITH
A HIGH AMPLITUDE TROUGH MOVING INTO THE NORTHERN ROCKIES. IT IS HARD
TO TELL IF THERE IS A STRONG MCV ASSOCIATED WITH THE CONVECTION OVER
SOUTHWEST KS, SO THE FORECAST ANTICIPATES THE PRECIP CONTINUING TO
DIMINISH AS THE LOW LEVEL JET WEAKENS LATER THIS MORNING. EVEN IF
THERE IS AN MCV, SOUTHWESTERLY FLOW IS LIKELY TO TAKE THE BETTER
VORTICITY ADVECTION NORTH INTO NEB OR SHEAR OUT THE MCV. MEANWHILE
MODELS SHOW 700MB TEMPS WARMING THROUGH THE AFTERNOON WITH NO
OBVIOUS FORCING. THEREFORE THINK THAT ONCE THE MORNING PRECIP ENDS,
THE AFTERNOON IS LIKELY TO REMAIN DRY WITH SKIES BECOMING MOSTLY
SUNNY. HIGHS TODAY ARE EXPECTED TO BE NEAR YESTERDAYS OR POSSIBLY A
DEGREE OR TWO WARMER. BECAUSE OF THIS THINK HEAT INDICES WILL AGAIN
BE AROUND 105 THIS AFTERNOON. THE MAIN UNCERTAINTY IS HOW MUCH WILL
DEWPOINT TEMPS MIX OUT THIS AFTERNOON. THE MODEL CONSENSUS KEEPS
HIGHER DEWPOINTS ACROSS EASTERN KS, AND THE KS RIVER VALLEY
TYPICALLY HAS HIGHER HUMIDITY. THEREFORE HAVE MORE CONFIDENCE IN THE
HIGHER HEAT INDICES OVER THE EASTERN THIRD OF THE FORECAST AREA AND
BACK WEST THROUGH THE KS RIVER VALLEY TO JUNCTION CITY. THIS IS
WHERE A HEAT ADVISORY WILL BE ISSUED FOR THIS AFTERNOON. THINK
BETTER MIXING OF DEWPOINTS MAY LIMIT THE POTENTIAL FOR HEAT INDICES
OF 105.

MODELS BRING A COLD FRONT TOWARDS NORTH CENTRAL KS LATE TONIGHT.
THEREFORE HAVE SOME SLIGHT CHANCE POPS LATE TONIGHT AS THE BOUNDARY
APPROACHES. FORCING AGAIN APPEARS TO BE LIMITED IN THE MODEL PROGS
SO THINK ANY ELEVATED STORMS WOULD BE PRETTY CLOSE TO THE BOUNDARY,
WHICH IS LIKELY TO REMAIN TO THE WEST OF THE FORECAST AREA
TONIGHT. THEREFORE THINK CHANCES AREN`T MUCH BETTER THAN 20
PERCENT. LOWS TONIGHT SHOULD BE VERY WARM AS AN INCREASING
PRESSURE GRADIENT KEEPS A SOUTH AND SOUTHWESTERLY WIND UP THROUGH
THE NIGHT. THINK LOWS WILL BE IN THE MID AND UPPER 70S.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 341 AM CDT MON JUL 27 2015

TUESDAY THROUGH WEDNESDAY...AN UPPER LEVEL TROUGH ACROSS THE
CENTRAL ROCKIES WILL LIFT NORTHEAST INTO THE NORTHERN PLAINS BY
TUESDAY NIGHT...THEN INTO THE UPPER GREAT LAKE STATES BY LATE
WEDNESDAY.

AS THE H5 TROUGH APPROACHES THE NORTHERN PLAINS LOW-LEVEL CAA WILL
HELP PUSH A COLD FRONT SOUTHEAST ACROSS NE INTO NORTH CENTRAL KS BY
LATE TUESDAY. THE 00Z NAM SOLUTION HAS THE FRONT MOVING INTO THE
NORTHWEST COUNTIES OF THE CWA BY 21Z...WHILE THE OTHER MODELS ARE
ABOUT 4 TO 6 HOURS SLOWER. THE BEST CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE CWA WILL PROBABLY OCCUR TUESDAY NIGHT AS A
LINE OF THUNDERSTORMS DEVELOP AHEAD OF THE FRONT FROM EASTERN
NE...SOUTHWEST INTO SOUTHWEST KS. THE LINE OF STORMS WILL MOVE
SOUTHEAST ACROSS THE CWA WEDNESDAY NIGHT. MUCAPE DURING THE NIGHT
MAY RAGE BETWEEN 1500 J/KG TO 2000 J/KG WITH INCREASING 0-6KM
EFFECTIVE SHEAR TO NEAR 30 KTS. THEREFORE SOME OF THE STORMS MAY BE
STRONG TO SEVERE TUESDAY NIGHT WITH THE PRIMARY HAZARD BEING
DAMAGING OUTFLOW WINDS AND HEAVY RAINFALL. ONCE THE FRONT PUSHES
SOUTHEAST OF THE CWA BY 12Z WED...WEAK ISENTROPIC LIFT NORTH OF THE
FRONTAL BOUNDARY COMBINED WITH ASCENT AHEAD OF THE SOUTHERN EDGE OF
THE NORTHERN PLAINS H5 ROUGH MAY ALLOW FOR SCATTERED ELEVATED
SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE CWA INTO WEDNESDAY
AFTERNOON.

HIGHS ON TUESDAY AHEAD OF THE SURFACE FRONT WILL REACH THE MID TO
UPPER 90S ACROSS THE CWA. LOW-LEVEL WINDS MAY VEER TO THE SOUTHWEST
TUESDAY AFTERNOON WHICH WILL ALLOW FOR DEEPER MIXING AND ALLOW
DEWPOINTS TO DROP INTO THE THE MID 60S TO LOWER 70S. THEREFORE, HEAT
INDICES MAY ONLY REACH THE 100 TO 105 DEGREE RANGE.

WEDNESDAY NIGHT...THE NORTHER PLAINS TROUGH WILL MOVE EAST ACROSS
THE GREAT LAKES STATES AND THE BETTER ASCENT WILL SHIFT EAST OF THE
AREA. ALSO WEAK CAA WILL CONTINUE ACROSS THE CENTRAL PLAINS AND
WILL PUSH THE FRONT SOUTHWARD INTO OK AND THE BETTER ZONE OF
ISENTROPIC LIFT NORTH OF THE FRONT WILL SHIFT SOUTH OF THE CWA.

THURSDAY THROUGH SUNDAY...THE TROUGH ACROSS THE GREAT LAKES STATES
WILL AMPLIFY SOUTHWARD ACROSS THE EAST CENTRAL US. THE UPPER LEVEL
RIDGE WILL AMPLIFY ACROSS THE WESTERN US. THE CENTRAL AND SOUTHERN
PLAINS WILL BE IN WEAK NORTHWEST FLOW ALOFT THROUGH THE PERIOD. WEAK
UPPER LEVEL DISTURBANCES MAY PROVIDE CHANCES FOR SHOWERS AND
THUNDERSTORMS FRIDAY THROUGH SUNDAY. AT THIS TIME THE BETTER RAIN
CHANCES LOOKS TO BE ACROSS WESTERN KS...THOUGH SOME THUNDERSTORMS
COMPLEXES THAT DEVELOP ON THE HIGH PLAINS MAY HOLD TOGETHER AS THEY
TRACK SOUTHEAST ACROSS KS. AT THIS TIME IT IS TOO EARLY TO
PINPOINT THUNDERSTORM CHANCES. HIGHS WILL BE SLIGHTLY COOLER WITH
MID 80S TO LOWER 90S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1218 PM CDT MON JUL 27 2015

VFR CONDITIONS EXPECTED THROUGH THE PERIOD. MAY SEE A FEW VCSH FOR
A FEW MORE HOURS THIS AFTERNOON BUT OUTSIDE OF THOSE EXPECT DRY
CONDITIONS AND SOUTH SOUTHEASTERLY WINDS.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ011-012-022>024-
026-036-038>040-054>056-058-059.

&&

$$

SHORT TERM...WOLTERS
LONG TERM...GARGAN
AVIATION...67



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