876 FXUS63 KTOP 192031 AFDTOP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 331 PM CDT FRI JUL 19 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 325 PM CDT FRI JUL 19 2013 WATER VAPOR IMAGERY AT 19Z SHOWS A FEW AREAS OF INTEREST ACROSS THE REGION. CENTER OF THE ELONGATED UPPER TROF WAS TRACKING EASTWARD TOWARDS THE MIDWEST AND GREAT LAKES REGION. FURTHER WEST A WEAKER TROF WAS BRINGING ADDITIONAL MID LEVEL MOISTURE SOUTHWARD OVER NEBRASKA AND ENTERING NORTHERN KANSAS THIS AFTERNOON. SURFACE ANALYSIS SHOWS THE COLD FRONT POSITIONED OVER SOUTHEAST NEBRASKA INTO PORTIONS OF NORTH CENTRAL KANSAS. WHILE THE SFC AND MID LEVEL FLOW IS WEAK...JUST ENOUGH SURFACE CONVERGENCE ALONG WITH THE LACK OF CAPPING INVERSION IN PLACE HAS ALLOWED FOR SHOWERS AND THUNDERSTORMS TO DEVELOP OVER PORTIONS OF SOUTHERN NEBRASKA. EXPECT WIDELY SCATTERED STORMS TO CONTINUE AS THIS FRONT SAGS SOUTHWARD LATE THIS AFTERNOON OVER NORTH CENTRAL AREAS OF THE CWA...SPREADING ACROSS THE ENTIRE CWA THIS EVENING. SURFACE BASED CAPE UP TO 2000 J/KG JUST SOUTH OF THE BOUNDARY WITH TEMPERATURES WELL PAST THE CONVECTIVE TEMP SHOULD PROVIDE ENOUGH INSTABILITY FOR STORMS TO FORM. HOWEVER LACK OF STRONG FORCING ALOFT AND BULK SHEAR VECTORS THROUGH 6 KM AT 10 TO 15 MPH SUGGESTS SOME UNCERTAINTY AS TO STORMS BEING ABLE TO MAINTAIN THEIR INTENSITY THROUGH THE EVENING. SHORT TERM GUIDANCE IS STILL VARYING SLIGHTLY ON FRONTAL PLACEMENT AND MESOSCALE FORCING MECHANISMS TO GENERATE ADDITIONAL PRECIP SO OVERALL KEPT THE GOING TREND OF CENTERING HIGHEST POPS FROM 00Z TO 06Z WHERE THE BEST CONVERGENCE LIES AS THE SFC FRONT PROGRESSES THRU THE CWA. BY SATURDAY MORNING AT 12Z...SUBSIDENCE COMING IN FROM SOUTHEAST NEBRASKA ALONG WITH NO NOTABLE FORCING LEAD TO TAPERING OFF POPS OVER THE NORTHERN HALF OF THE CWA. EXPECT THE SURFACE FRONT TO DIFFUSE/LINGER OVER EAST CENTRAL AREAS OR PERHAPS JUST SOUTH OF THE CWA WHERE ADDITIONAL WEAK SHOWERS AND PERHAPS A STORM MAY PERSIST THROUGH THE MORNING. A STRONGER MID LEVEL WAVE TRACKS SOUTHEAST OVER NEBRASKA SATURDAY AFTERNOON WITH SHOWERS AND THUNDERSTORMS ONCE AGAIN POSSIBLE. WHILE THE LATEST GFS MAY BE OVER DONE ON QPF AMOUNTS...BELIEVE MODELS ARE IN AN OVERALL AGREEMENT WITH CHANCES FOR PRECIPITATION GRADUALLY INCREASING THROUGH THE LATE AFTERNOON AS THE WAVE APPROACHES SAT EVENING. LACK OF STRONG ADVECTION WITH THE BOUNDARY...CLOUD COVER AND WEAK WINDS SHOULD RESTRICT HIGHS ON SATURDAY TO THE LOW 90S. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 325 PM CDT FRI JUL 19 2013 EXTENDED FORECAST REMAINS TRICKY AS SENSIBLE WEATHER MAY BE IMPACTED DAILY BY PASSING PRECIPITATION OR ITS OUTFLOW...AND THE LOCATION OF THE LARGER SCALE FRONT ALONG AND SOUTH OF WHICH IS POISED CONSIDERABLE WARM AIR. SUN/MON...GOOD CONSENSUS REMAINS FOR A COMPLEX OF STORMS TO FORM ON THE HIGH PLAINS AND ROLL SOUTHEAST INTO CENTRAL AND EASTERN KANSAS IN THE OVERNIGHT HOURS INTO SUNDAY MORNING. SOME SLOWING OF THE SHORTWAVE TROF HAS SPREAD POP CHANCES INTO SUNDAY DURING THE DAY. WOULD EXPECT A BREAK IN COVERAGE WITH BRIEF PERIOD OF SUBSIDENCE BEFORE ANOTHER ROUND IS FORECAST TO DEVELOP AGAIN TOWARD THE EARLY MORNING HOURS ON MONDAY AND MOVES EASTWARD BY AFTERNOON. THINK THIS WILL LEAVE ENOUGH TIME FOR COLD POOL TO WASH OUT FROM PREVIOUS STORMS...AND RESULT IN IN A RISE FROM SUNDAYS HIGHS IN THE LOW 90S BACK UP INTO THE MIDDLE 90S BY LATER MONDAY AFTERNOON. LATEST EC AS COME IN WEAKER WITH THESE PRECIP CHANCES BY KEEPING THE BOUNDARY TO THE SOUTH AND GENERATING LATE DAY RAIN CHANCES THERE...WHICH ON THE UPSIDE COULD MAKE FOR A COOLER DAY HERE ON MONDAY. FOR THE INITIAL SYSTEM EARLY SUNDAY...WITH BOTH INVERTED V TYPE SOUNDINGS IN THE LOWER LEVELS AND STILL GENERALLY 1.5 INCHES OF WATER IN THE SOUNDINGS...THINK PRIMARY HAZARDS WOULD BE STRONG WINDS AND LOCALLY HEAVY RAINFALL FROM STORMS THAT COME THROUGH. TUES THROUGH FRIDAY...THE SERIES OF NIGHTLY PRECIP CHANCES CONTINUES INTO THE MIDDLE AND END OF THE WEEK. WAVE OVER OUR AREA GETS A SOUTHERLY PUSH AS SHORTWAVE TROF MOVES ACROSS SOUTHERN CANADA AND BRINGS OVERNIGHT STORM CHANCES MONDAY NIGHT INTO TUESDAY. ONCE AGAIN THIS COULD LEAVE THE OPPORTUNITY FOR THE ATMOSPHERE TO RECOVER BETWEEN SYSTEMS AND HEAT BACK UP BY TUESDAY AFTERNOON. THIS PROCESS REPEATS TUESDAY NIGHT INTO WEDNESDAY ALTHOUGH THIS SYSTEM APPEARS STRONGER. THIS COOLER PUSH FROM THE NORTH MAY GET SOME REINFORCEMENT AS THIS PASSING WAVE DROPS INTO THE OHIO VALLEY AND STRENGTHENS THE EASTERN TROF...WHICH IN TURN DRAWS THE FLOW ALOFT OVER THE PLAINS MORE OUT OF THE NW FOR WED/THURS. HOWEVER UPPER HIGH AND ASSOCIATED WARM AIR REMAINS ON THE DOORSTEP OVER WESTERN KS...AND WITH STRONGER SURFACE FRONT PROGGED TO SLIDE SOUTHWARD LATE FRIDAY...COULD GET ONE MORE SPIKE IN HIGH TEMPERATURES AS AREA MIXES INTO THE THERMAL RIDGE AHEAD OF THE FRONT. WILL DEPEND ON SPEED OF THE FRONT WHICH IS TOO FAR OUT TO CALL FOR TIMING. &&
Posted on: Fri, 19 Jul 2013 20:38:57 +0000