Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 060450
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1150 PM CDT SUN JUL 5 2015

...UPDATE TO AVIATION FORECAST DISCUSSION...

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 325 PM CDT SUN JUL 5 2015

AT 3 PM ON SUNDAY...TEMPERATURES HAVE WARMED INTO THE UPPER 80S TO
UPPER 90S WHILE DEWPOINTS HAVE HELD IN THE UPPER 60S TO LOWER
70S. THIS HAS LED TO HEAT INDEX READINGS IN THE 95 TO 105 RANGE
AND ARE EXPECTED TO HOLD IN THIS RANGE AS ANY FURTHER SIGNIFICANT
INCREASE IN TEMPERATURE WOULD LIKELY BE ACCOMPANIED BY A DECREASE
IN DEWPOINT. THESE SURFACE CONDITIONS HAVE ALSO COMBINED WITH
MODEST LAPSE RATES TO ESTABLISH SURFACE BASED CAPE OF 2000+ J/KG
ACROSS THE AREA. WHILE SOME EARLY AFTERNOON STORMS HAVE LONG SINCE
WEAKENED, THERE REMAINS A FEW AREAS OF WEAK CONVERGENCE ACROSS THE
FORECAST AREA AND ALSO SOME WEAK REMNANT OUTFLOW BOUNDARIES. ONE
OUTFLOW OVER MORRIS COUNTY HAS HAD SOME CUMULUS DEVELOPMENT ALONG
IT BUT FAILED TO SUSTAIN. WILL NEED TO MONITOR CONVECTIVE
CONDITIONS THROUGH SUNSET AS THERE IS A SLIGHT CHANCE FOR ISOLATED
DEVELOPMENT...AND ANY SUCH DEVELOPMENT WOULD HAVE POTENTIAL TO
PRODUCE LOCALLY DAMAGING DOWNBURST WINDS AND POSSIBLY SEVERE HAIL.
ANY STORMS WOULD DISSIPATE AFTER SUNSET.

WIDESPREAD STORMS WILL DEVELOP ACROSS NEBRASKA AND THE DAKOTAS
OVERNIGHT BUT THE FORCING FOR THIS ACTIVITY WILL STAY WELL NORTH
OF THE AREA. HOWEVER...BY MORNING IT IS LIKELY THAT OUTFLOW WILL
APPROACH NORTHERN PARTS OF THE FORECAST AREA AND AS THE UPPER VORT
MAX ALSO APPROACHES TO INTERACT WITH INCREASING INSTABILITY AND
CONVERGENCE...EXPECT THUNDERSTORMS TO DEVELOP INTO NORTHER KANSAS.
THIS MAY BE ONGOING AT SUNRISE BUT SEEMS MORE LIKELY TO WAIT UNTIL
LATE MORNING FOR STORMS TO BECOME MORE WIDESPREAD. THERE WILL BE
AMPLE INSTABILITY AHEAD OF THE FRONT THROUGH THE AFTERNOON AND
EVENING BUT DEEP LAYER WIND SHEAR WILL BE MEAGER. THIS SHOULD
LIMIT OVERALL SEVERE POTENTIAL BUT WITH SUCH STRONG FORCING AND
INSTABILITY...ALONG WITH A VERY MOIST AIRMASS AND HOT TEMPS AHEAD
OF THE FRONT...COULD SEE POTENTIAL FOR STRONG DOWNBURSTS WITHIN
THE HEAVIER STORMS AND POSSIBLY SOME SEVERE HAIL. PWAT VALUES ARE
LIKELY TO APPROACH OR EVEN EXCEED 2 INCHES AHEAD OF THE CONVECTION
AND WILL RESULT IN VERY HIGH RAINFALL RATES WITH THE STRONGER
CONVECTION. THUS...ANY TRAINING OR SLOWING OF THE FRONTAL
PROGRESSION COULD QUICKLY RESULT IN SOME FLASH FLOODING. THE MOST
LIKELY AREA FOR THIS CURRENTLY APPEARS TO BE SOUTH OF A
MINNEAPOLIS TO MANHATTAN TO SENECA LINE BETWEEN 3 PM AND 3 AM AS
THE FRONT SLOWS AND THE LLJ ASSISTS WITH MOISTURE TRANSPORT.

THE FRONT IS FORECAST TO MOVE THROUGH THE AREA BY TUESDAY MORNING
BUT STALL OVER FAR NORTHERN OKLAHOMA. FROM THAT POINT THROUGH
WEDNESDAY NIGHT...ADDITIONAL SHORT WAVE TROUGH ENERGY IS LIKELY TO
INTERACT WITH THE FRONT AND BRING ADDITIONAL ROUNDS OF HEAVY RAIN
TO SOUTHERN AND EAST CENTRAL KANSAS. CURRENT TOTAL RAINFALL
FORECASTS THROUGH LATE WEDNESDAY APPROACH 4 INCHES IN EAST CENTRAL
KANSAS AND COULD SEE A RIVER FLOODING THREAT MATERIALIZE AND
WORSEN WITH TIME IF THIS PLAYS OUT. TEMPERATURES WILL ALSO BE
MARKEDLY COOLER THROUGH THIS PERIOD WITH HIGHS IN THE 70S ALONG
WITH QUITE A BIT OF CLOUD COVER.

.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 325 PM CDT SUN JUL 5 2015

BY WEDNESDAY NIGHT THE CLOSED MID LEVEL LOW PRESSURE OVER THE WEST
COAST CONTINUES TO SPIN AS IT GRADUALLY SLIDES ALONG THE NORTHERN
PERIPHERY OF THE UPPER RIDGE. A FEW SHORTWAVES ARE FORECAST TO BREAK
AWAY FROM THE MAIN LOW AND PROGRESS EASTWARD OVER THE CENTRAL
ROCKIES AND EVENTUALLY THE CENTRAL PLAINS. THE MODELS ARE STRUGGLING
WITH THE TIMING AND EXACT TRACK OF THESE WAVES THEREFORE THERE IS
NOT MUCH CONFIDENCE IN THE MID WEEK TIME FRAME. FOR NOW IT APPEARS A
WAVE MAY PASS OVER THE FORECAST AREA ON THURSDAY BRINGING THE CHANCE
FOR SHOWERS AND STORMS. DEEP LAYER SHEAR IS FAIRLY WEAK ALTHOUGH
SOME INSTABILITY WILL BE PRESENT AND THE DRIVING FACTOR FOR ANY
STRONG STORMS. THE AREA MAY BEGIN TO DRY OUT AFTER THAT AS THE
CLOSED WAVE TRACKS OVER THE NORTHERN US AND ALLOWING THE UPPER RIDGE
TO BUILD WESTWARD OVER THE SOUTHERN US. BY LATE WEEKEND THE CLOSED
WAVE IS FORECAST TO DIG SOUTHEASTWARD OVER THE UPPER MIDWEST, WHICH
WILL BRING A COLD FRONT INTO THE REGION AND POSSIBLY A BETTER CHANCE
FOR PRECIP.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1144 PM CDT SUN JUL 5 2015

FAIRLY TIGHT PRESSURE GRADIENT TONIGHT SHOULD KEEP SOUTHERLY WINDS
UP IN THE 10-15 KT RANGE TONIGHT. COLD FRONT IS FORECAST BY NEW
00Z GUIDANCE TO MOVE THROUGH THE TAF LOCATIONS LATE MONDAY
AFTERNOON. THE BOUNDARY SHOULD ENCOUNTER A VERY MOIST AND UNCAPPED
UNSTABLE AIRMASS OVER NORTHEAST KANSAS. EXPECT MULTICELL THUNDERSTORMS
TO DEVELOP BY MID AFTERNOON AND BECOME LINEAR IN NATURE. BASED ON
00Z MODEL SOUNDINGS...FORECASTED POST FRONTAL MVFR CIGS AND
SHOWERS.

&&

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

$$

SHORT TERM...BARJENBRUCH
LONG TERM...SANDERS
AVIATION...JOHNSON



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