000
FXUS63 KTOP 180854
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
354 AM CDT SAT MAY 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SAT MAY 18 2013

SHORT WAVE RIDGING IS RATHER EVIDENT ON THE 08Z WATER VAPOR IMAGERY
CENTERED OVER THE SOUTHERN AND CENTRAL PLAINS WITH THE RIDGE AXIS
LOCATED ROUGHLY OVER CENTRAL AND EASTERN KANSAS. SURFACE
OBSERVATIONS AT MICROWAVE IMAGERY SHOWS A DECENT STRATUS LAYER
ACROSS CENTRAL AND SOUTHERN KANSAS. EXPECT THIS AREA OF STRATUS TO
MOVE NORTH AND OVER THE FAR WESTERN ZONES THROUGH THE MORNING HOURS
BEFORE EVENTUALLY CLEARING OUT LATER TODAY. WITH THE RIDGE OVERHEAD
AND STRONG LOW/MID LEVEL CAPPING EXPECT A CUMULUS FIELD TO FORM WITH
DIURNAL HEATING...BUT STORMS ARE EXCEEDINGLY UNLIKELY TO FORM DUE TO
THE VERY WARM 700-800 MB TEMPERATURES. EXPECT RATHER WARM
TEMPERATURES TODAY...AS STRONG SUBSIDENCE WILL BE ONGOING DUE TO THE
RIDGE IN PLACE...AS WELL AS MIXING TO AROUND 850 MB. AS A RESULT THE
DAYTIME HIGHS WILL LIKELY REACH THE MIDDLE TO UPPER 80S TODAY.

FURTHER TO THE WEST A WELL PRONOUNCED DRY LINE WILL FORM IN SW/SC
KANSAS AND WILL LIKELY BE THE FOCUS FOR AFTERNOON THUNDERSTORMS ON
SATURDAY AFTERNOON. THESE STORMS WILL BE WELL WEST OF THE FORECAST
AREA IN THEIR STRONGEST FORM...BUT THEY WILL LIKELY ADVECT NORTH AND
EAST THROUGH THE EVENING AND OVERNIGHT HOURS...PERHAPS FORMING AN
OVERNIGHT MCS WHICH WOULD SLIDE EAST-NORTHEAST THROUGH THE FORECAST
AREA SATURDAY NIGHT INTO SUNDAY MORNING. WITH THE AFOREMENTIONED CAP
SOLIDLY IN PLACE ANY STORMS MOVING INTO NORTH CENTRAL AND NORTHEAST
KANSAS WILL HAVE A FORMIDABLE CHALLENGE TO OVERCOME ESPECIALLY THE
FURTHER EAST YOU GO...BUT IT WILL BE POSSIBLE FOR THE
WESTERN/CENTRAL KANSAS CONVECTION TO LEAK INTO THE AREA THIS EVENING
AND OVERNIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 315 AM CDT SAT MAY 18 2013

SUNDAY...SEVERAL MODELS STILL SHOWING CONVECTION THAT DEVELOPS
OVER CENTRAL AND SW KANSAS MOVING NORTHEASTWARD INTO THE FORECAST
AREA THROUGH THE EARLY MORNING HOURS. WITH A CAP IN PLACE OVER
MUCH OF THE FORECAST AREA AM NOT HIGHLY CONFIDENT THAT A
THUNDERSTORM CLUSTER WILL BE ABLE TO ERODE THE CAP ON ITS OWN
ENOUGH FOR LASTING OVERNIGHT STORMS. THIS WILL HAVE SOME IMPACT
ON THE SEVERE WEATHER CHANCES FOR SUNDAY AFTERNOON...ALTHOUGH JUST
ABOUT ALL COMPUTER DEPICTIONS LIFT PRECIP OFF TO THE NORTH AS THE
CAP ALOFT REDEVELOPS IN THE AFTERNOON. COULD ALSO SEE SOME
ISOLD/SCT STORMS NORTH NEAR THE NEBRASKA BORDER ON THE EDGE OF THE
STRONGER CAPPING INVERSION.

SUNDAY AFTERNOON AND EVENING ARE STILL SHAPING UP TO BRING THE
CHANCE FOR SIGNIFICANT SEVERE WEATHER TO THE REGION. BY 18Z THE
UPPER TROF IS APPROACHING EASTERN KS WITH A NEGATIVE
TILT...SURFACE LOW HAS SHIFTED TO CENTRAL KANSAS AND INSTABILITY
INCREASES INTO 2500-3500J/KG...WITH THE NAM AS HIGH AS 4500 OUT
WEST OF MANHATTAN. 0-6KM BULK SHEAR RISES FROM 35KTS TO NEAR 50KTS
AROUND 0Z IN THE EASTERN COUNTIES...WITH THE GFS SHOWING 35KTS
FROM 0-1KM. LAPSE RATES ALOFT ARE 9C OR GREATER FOR A GOOD PORTION
OF THE SOUNDING...WITH AN UPPER JET MOVING PERPENDICULAR ACROSS
THE SURFACE TROF ALONG THE KS/OK BORDER THROUGH THE EVENING HOURS.
WITH SUCH STRONG INSTABILITY AND LAPSE RATES...AND GIVEN LACK OF
STRONG TURNING WITH HEIGHT IN THE WIND PROFILE...INITIAL THINKING
IS THAT LARGE HAIL...BASEBALL SIZE OR LARGER...IS A POSSIBILITY
WHERE STORMS CAN FORM LATER SUNDAY AFTERNOON. CANNOT RULE OUT
ISOLATED TORNADOES GIVEN STRONG INSTABILITY AND AVAILABLE SHEAR IN
THE COLUMN...AND WILL ALSO NEED TO KEEP WIND THREAT IN MIND FROM
NOT ONLY STRONG DISCRETE CELLS BUT ALSO POTENTIAL FOR LINE OF
STORMS TO FORM AND MOVE EASTWARD. MUCH OF THE EAST AND SOUTHEAST
PORTIONS OF OUR FORECAST AREA HAVE BEEN PUT IN A MODERATE DAY 2
RISK FOR THIS POTENTIAL. CHANCES FOR OVERNIGHT ACTIVITY MAY ALSO
HAVE AN INFLUENCE ON TIMING AND ONSET OF SEVERE WEATHER ON SUNDAY.
AT THIS TIME THINK BEST CHANCES ARE IN THE AFTERNOON INTO THE
EVENING HOURS...WITH LARGE HAIL...WIND GUSTS AND ISOLATED
TORNADOES A POSSIBILITY...WITH THE GREATER THREAT IN AREAS EAST OF
ABILENE. 67

FOR SUNDAY NIGHT...EC WANTS TO MOVE THE SECONDARY MAIN LOW OVER THE
AREA GOING INTO TUESDAY MORNING WHICH MAY TRIGGER YET ANOTHER LINE
OF SHOWERS AND STORMS FOR THE CENTRAL DN SC PARTS OF THE STATE. KEPT
HIGHER POPS ACROSS THE SE FOR POSSIBLY BOUNDARY HANGING UP OVER
THAT AREA.

TUESDAY AND WEDNESDAY UPPER LOW CONTINUES TO SLOWLY SIT AND SPIN
OVER THE NORTHERN PLAINS THROUGH THURSDAY BEFORE IT STARTS TO
SHIFT EASTWARD. COOLER THAN NORMAL TEMPERATURES MAKE A BRIEF
RETURN THROUGH FRIDAY AS COOLER HIGH PRESSURE SETTLES SOUTHWARD
FROM THE NORTHERN PLAINS. 67

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM CDT FRI MAY 17 2013

CONFIDENCE IN IFR VSBY IS IS DIMINISHING AS OBJECTIVE GUIDANCE HAS
COME IN AND BACKED OFF ON VSBY RESTRICTIONS AND WINDS HAVE NOT
BEEN AS LIGHT AS EXPECTED. STILL THINK THERE WILL BE ENOUGH
RADIATIONAL COOLING FOR SOME MVFR VSBY TO OCCUR...BUT WILL REMOVE
THE MENTION OF IFR VSBY. DO NOT HAVE ANY CONFIDENCE IN THE NAM
GENERATING MID DAY CONVECTION IN SOUTHEASTERN KS. THERE IS NO GOOD
EXPLANATION FOR THE NAMS DISJOINTED COOLING OF MID LEVEL TEMPS
WHICH WEAKENS THE CAP. THE RAP ON THE OTHER HAND SHOWS THE CAP
HOLDING THROUGH THE LATE AFTERNOON WITH SFC TEMPS WARMING TO
AROUND 90. THEREFORE WILL KEEP THE TERMINALS DRY THROUGH THE
FORECAST.


&&

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

$$

SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...WOLTERS