Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 280419
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1119 PM CDT SAT JUN 27 2015

...UPDATE TO AVIATION FORECAST DISCUSSION...

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 218 PM CDT SAT JUN 27 2015

1930Z WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL RIDGE OVER THE
INTERMOUNTAIN WEST WHILE A WELL DEFINED SHORTWAVE DIGS INTO NORTHERN
MN. THIS LEAVES NORTHWEST FLOW OVER THE FORECAST AREA. AT THE
SURFACE, A WEAKENING RIDGE OF HIGH PRESSURE WAS CENTERED OVER
WESTERN KS.

FOR TONIGHT, THE WEATHER SHOULD REMAIN QUIET AS THE RIDGE AXIS
PASSES FROM WEST TO EAST ACROSS THE STATE. SO WITH NO LIFT AND NO
FORCING NOTED IMMEDIATELY UPSTREAM, HAVE CONTINUED WITH A DRY
FORECAST. LOWS TONIGHT SHOULD FALL BACK INTO THE MID 60. THINK THAT
SURFACE WINDS BECOMING MORE SOUTHERLY AFTER MIDNIGHT MAY HELP KEEP
TEMPS A DEGREE OR TWO WARMER THAN THIS MORNING.

THE SHORTWAVE OVER THE UPPER MIDWEST IS EXPECTED TO PROPAGATE SOUTH
THROUGH MO AND IL DURING THE DAY SUNDAY BRINGING A SURFACE COLD
FRONT THROUGH THE AREA. IT CONTINUES TO LOOK LIKE THE NAM IS
OVERDOING THE SURFACE DEWPOINTS AHEAD OF THE FRONT AND THEREFORE IS
TO HIGH WITH IT`S PROG OF INSTABILITY. NEVERTHELESS THERE MAY BE
ENOUGH INSTABILITY AHEAD OF THE FRONT (GFS SHOWS CAPE AROUND 1500
J/KG) FOR A FEW STORMS TO DEVELOP DURING THE AFTERNOON ACROSS EAST
CENTRAL KS. AT THIS POINT THINK CONVECTION IS PROBABLY GOING TO BE
ISOLATED IN NATURE ACROSS EAST CENTRAL KS DUE TO THE STRONGER
FORCING AFFECTING AREAS WELL EAST OF THE FORECAST AREA. BUT WITH
LITTLE INHIBITION AND THE LIFT OF THE BOUNDARY THERE IS A CHANCE FOR
SOME STORMS. DEEP LAYER SHEAR IS EXPECTED TO BE AROUND 40KTS WHICH
WOULD BE GOOD ENOUGH FOR SOME ORGANIZATION TO THE UPDRAFTS.
THEREFORE COULD SEE SOME LARGE HAIL WITH THE STORMS. IF THE BOUNDARY
LAYER MIXES REALLY WELL AHEAD OF THE FRONT, WE MAY NEED TO WATCH OUT
FOR MICROBURST WINDS AS FORECAST SOUNDINGS SUGGEST AN INVERTED V
PROFILE DURING THE AFTERNOON. HAVE HIGHS IN THE UPPER 80S ALONG THE
NEB STATE LINE THINKING THE FRONT SHOULD MOVE THROUGH EARLIER IN THE
DAY LIMITING MIXING. BETTER MIXING AND WARM AIR ADVECTION AHEAD OF
THE FRONT IS EXPECTED TO WARM TEMPS INTO THE LOWER AND MID 90S ALONG
THE KS RIVER VALLEY AND INTO EAST CENTRAL KS.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 218 PM CDT SAT JUN 27 2015

A LARGE UPPER RIDGE OVER THE WESTERN CONUS WITH A DOWNSTREAM
TROUGH OVER THE EASTERN CONUS IS THE EXPECTED WEATHER PATTERN AT
THE START OF THE LONG TERM. THE 12Z ECMWF/GFS BOTH SLOWLY
RETROGRADE THE UPPER RIDGE WEST TOWARDS THE WEST COAST DURING THE
FORECAST PERIOD AS IT FLATTENS SOME DUE TO SHORTWAVE ENERGY
MOVING OVER THE TOP OF THE RIDGE. UNDER THIS FLOW REGIME...THE
CENTRAL CONUS SHOULD BE IN NORTHWEST FLOW WITH EMBEDDED SHORTWAVE
ENERGY MOVING THROUGH. AFTER A FEW DAYS OF DRY WEATHER EARLY THIS
WEEK...OCCASIONAL SHORTWAVE ENGERY INTERACTING WITH A FRONTAL
BOUNDARY IN THE VICINITY SHOULD RESULT IN THUNDERSTORM CHANCES
FROM WEDNESDAY ONWARD. FORECAST CONFIDENCE IN EXACT TIMING OF
PRECIPITATION CHANCES DECREASES BY LATE IN THE EXTENDED DUE TO
UNCERTAINTIES IN SHORTWAVE ENERGY TIMING AND THE FRONTAL POSITION.
THEREFORE...WILL FORECAST GENERALY LOW POPS IN ANY GIVEN PERIOD.

THE FRONTAL BOUNDARY MOVING THROUGH SUNDAY AFTERNOON AND EVENING
SHOULD BE FOLLOWED BY A WEAK HIGH PRESSURE SYSTEM OVER THE CENTRAL
PLAINS ON MONDAY AND MONDAY NIGHT. RETURN FLOW AND MOISTURE
ADVECTION INTERACTING WITH A FRONTAL BOUNDARY WILL RESULT IN
THE NEXT THUNDERSTORM CHANCES IN NORTHEAST KANSAS ON WEDNESDAY.

THE WARMEST DAY NEXT WEEK SHOULD OCCUR ON TUESDAY DUE TO WARM
ADVECTION AND DRY WEATHER. WITH THE SURFACE FRONT IN THE VICINITY
AND ASSOCIATED CLOUD COVER AND THUNDERSTORM CHANCES...TEMPERATURES
SHOULD BE AT OR BELOW NORMAL IN THE EXTENDED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1115 PM CDT SAT JUN 27 2015

VFR PREVAILS AT TERMINALS WITH HIGH PRESSURE INFLUENCE SHIFTING
SOUTHWARD. FRONTAL PASSAGE VEERS SOUTHWEST WINDS NEAR 10 KTS TO
THE NORTHWEST AFTER 18Z. MODEL GUIDANCE CONTINUES TO DEVELOP TSRA
SOUTH OF TERMINALS NEAR THE FRONTAL BOUNDARY.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...WOLTERS
LONG TERM...JONHSON
AVIATION...BOWEN


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