Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 050440 AAA
AFDTOP

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TOPEKA KS
1140 PM CDT SAT JUL 4 2015

...UPDATE TO AVIATION FORECAST DISCUSSION...

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 312 PM CDT SAT JUL 4 2015

INDEPENDENCE DAY HAS BEEN DRY AND WARM WITH A SOUTHEAST BREEZE...AND
THESE CONDITIONS ARE LIKELY TO CONTINUE THROUGH THE EVENING HOURS AS
A MODERATE CAP SHOULD LIMIT ANY CONVECTIVE DEVELOPMENT...EVEN WITH
INCOMING SHORT WAVE ENERGY. WITH NO PRECIPITATION EXPECTED...AND
SKIES CLEARING OUT THIS EVENING...IT SHOULD BE A BEAUTIFUL FEW HOURS
SURROUNDING SUNSET WITH TEMPERATURES AT 10 PM IN THE MIDDLE TO UPPER
70S WITH CONTINUED LIGHT SOUTHEAST WINDS.

AS THE NIGHT PROGRESSES...EXPECT A WEAKLY ORGANIZED MCS TO MOVE
SOUTH OUT OF CENTRAL AND WESTERN NEBRASKA. AT THE SAME TIME...THE
LOW LEVEL JET WILL INCREASE INTO CENTRAL KANSAS TO PROVIDE MOIST
ADVECTION ALOFT BENEATH MODERATELY STEEP MID LEVEL LAPSE RATES WHICH
SHOULD HELP TO MAINTAIN THE MCS TO SOME DEGREE INTO CENTRAL AND
PERHAPS PARTS OF EASTERN KANSAS. THE MOST LIKELY TIMING FOR THIS
APPEARS TO FALL BETWEEN 3 AM AND 10 AM WITH THE PRIMARY UNCERTAINTY
BEING IN PRECIPITATION COVERAGE WITH EASTWARD EXTENT. MUCAPE MAY BE
ON THE ORDER OF 1500 J/KG DURING THIS PERIOD WITH SOME MODERATE
EFFECTIVE SHEAR BUT BELIEVE THE SEVERE THREAT TO BE LOW WITH
POTENTIAL FOR A FEW MARGINALLY SEVERE HAIL STONES...AND AN OUTSIDE
CHANCE FOR STRONG WINDS...AND LIKELY CONFINED TO THE WESTERN HALF OF
THE FORECAST AREA.

MORNING ACTIVITY SHOULD DISSIPATE AND/OR SHIFT SOUTHEAST ON SUNDAY
WITH A WARM AND MUGGY DAY ENSUING. SO LONG AS SUNSHINE IS NOT
LIMITED BY WIDESPREAD CLOUD COVER...AND IT SHOULD NOT BE BY
AFTERNOON...EXPECT HIGHS IN THE LOWER TO MID 90S WITH DEWPOINTS
CLIMBING TO AROUND 70. THIS SHOULD GENERATE MODERATE TO STRONG
INSTABILITY PARTICULARLY IN EASTERN KANSAS BY THE AFTERNOON WITH
MINIMAL INHIBITION BUT WHAT IS LACKING IS A STRONG FORCING MECHANISM
TO INITIATE THUNDERSTORMS. THERE ARE SUGGESTIONS OF A WEAK
CONVERGENCE ZONE IN EASTERN PARTS OF THE FORECAST AREA AND WILL WANT
TO WATCH ANY OUTFLOW THAT MAY DEVELOP WITH EARLY CONVECTION BUT FOR
NOW ONLY HAVE LOW END CHANCE POPS MAINLY CONFINED TO AREAS EAST OF A
MARYSVILLE TO COUNCIL GROVE LINE. IF A STORM IS ABLE TO DEVELOP...
QUALITY INSTABILITY COMBINED WITH 25-35 KTS OF 0-6 KM SHEAR COULD
SUPPORT A LOCALIZED HAIL OR DAMAGING WIND POTENTIAL.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 312 PM CDT SAT JUL 4 2015

ON SUNDAY NIGHT A SHORTWAVE TROUGH WILL TRACK EAST-NORTHEASTWARD
OVER SD AND NE, WHICH WILL GUIDE A COLD FRONT SOUTHEASTWARD THROUGH
THE REGION. THIS WAVE IS ON TRACK TO GET ABSORBED BY A DECENT
SHORTWAVE DIGGING ACROSS SOUTHERN CANADA AND NORTHERN US. SOME OF
THIS ENERGY APPEARS TO EXTEND SOUTHWARD OVER KS AND MAY PROVIDE
ENOUGH LIFT FOR ELEVATED SHOWERS DURING THE MORNING ACROSS NORTHERN
KS. SOUTHERLY FLOW AHEAD OF THE WAVE WILL ALLOW DEEPER MOISTURE TO
ADVECT INTO THE REGION. THE DEW POINTS WILL STEADILY INCREASE DURING
THE DAY MONDAY AND COULD REACH THE LOWER 70S BEFORE FRONTAL PASSAGE.
A LINE OF STORMS WILL LIKELY DEVELOP ALONG AND BEHIND THIS FRONT AS
IT PROGRESSES SOUTHEASTWARD THROUGH AREA. THERE IS GOOD AGREEMENT
THAT THE MID LEVEL LAPSE RATES WILL NOT BE THAT STEEP, AND THE DEEP
LAYER SHEAR MAY ONLY BE AROUND 20 KTS. INSTABILITY WILL PROBABLY BE
SOMEWHERE BETWEEN 2000-3000 J/KG, WHICH COULD SUPPORT ISOLATED LARGE
HAIL AND DAMAGING WINDS. ALTHOUGH THERE ARE SOME TIMING ISSUES WITH
REGARDS TO THE SPEED OF THE FRONT. THE NAM AND GEM ARE THE SLOWEST
BRINGING THE FRONT THROUGH THE AFTERNOON AND EVENING HOURS, WHILE
THE ECMWF AND GFS ARE ABOUT 3 TO 6 HOURS FASTER. THIS WILL HAVE
IMPLICATIONS ON HOW UNSTABLE THE ENVIRONMENT WILL GET AHEAD OF THE
FRONT, WHICH LOCATIONS SEE THE ORGANIZED STORMS, AND WHEN NORTH
CENTRAL KS WILL DRY OUT. AS FOR NOW THE FASTEST SOLUTIONS WOULD
STILL SUGGEST THE FRONT WILL RUN INTO SOME PRETTY UNSTABLE AIR
ACROSS EAST CENTRAL AND SOUTHEAST KS AT SOME POINT LATE MONDAY. A
WIDESPREAD RAIN IS EXPECTED WITH STORMS, WHICH COULD BE VERY HEAVY
AND EFFICIENT. MODELS AGREE THAT PWAT VALUES APPROACH AS HIGH AS 2.5
INCHES AND WARM CLOUD DEPTHS REACH 12 KFT THEREFORE SUPPORTING THIS
HEAVY RAIN THREAT. AVERAGE RAINFALL AMOUNTS OF 0.5-1.75 INCHES IS
EXPECTED MONDAY INTO MONDAY NIGHT WITH LOCALLY HIGHER AMOUNTS
POSSIBLE.

BOTH THE NAM AND GEM ARE SLOWER WITH THE FRONT THEREFORE IT STALLS
OUT IN SOUTHERN KS AS ANOTHER SHORTWAVE TRACKS OUT OF THE SOUTHWEST
US AND OVER THE REGION. THIS SCENARIO WOULD SEND ANOTHER ROUND OF
SHOWERS AND STORMS DURING THE DAY WEDNESDAY MAINLY IN SOUTHEAST KS.
WITH SATURATED GROUNDS IN PLACE FLOODING MAY BECOME AN ISSUE IS THIS
WERE TO OCCUR. THE ECMWF AND GFS ARE FURTHER SOUTH WITH THE BULK OF
THIS PRECIP POSING LESS OF A THREAT FOR ADDITIONAL FLOODING
ISSUES. GFS ENSEMBLES ALSO SUPPORT THE IDEA OF THIS WAVE AND
PRECIP MISSING MUCH OF THE FORECAST AREA WEDNESDAY. SEVERAL MORE
OF THESE WEAK SHORTWAVES ARE FORECAST TO MOVE OVER THE REGION EACH
CAUSING AN AREA OF SHOWERS AND STORMS SOMEWHERE. AT THIS POINT IT
IS DIFFICULT TO KNOW THE EXACT TIMING AND TRACK, BUT LATE WEEK
LOOKS TO REMAIN UNSETTLED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1138 PM CDT SAT JUL 4 2015

HAZE FROM AREA FIREWORKS WILL CAUSE MVFR VIS CONDS AT TOP/FOE
TONIGHT OTHERWISE LOOK FOR VFR VIS/CIG CONDS TO PREVAIL DURING THE
DAY ON SUNDAY. HRRR AND SHORT RANGE MODELS NOW SUGGESTING THAT ELEVATED
CONVECTION SHOULD STAY WEST OF MHK EARLY SUNDAY SO WILL NOT
INCLUDE ANY MENTION OF THUNDER AT THIS TIME.

&&

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

$$

SHORT TERM...BARJENBRACH
LONG TERM...SANDERS
AVIATION...OMITT



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