RSS FeedsIssued by NWS Topeka, KS
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000 FXUS63 KTOP 240532 AFDTOP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1132 PM CST MON NOV 23 2009 .UPDATE... FOR 06Z AVIATION. && .DISCUSSION... SEE PREVIOUS DISCUSSION. && .AVIATION... SHOWERS AND LOWER CIGS APPROACHING MHK ATTM AS UPPER LOW MOVES ACROSS EASTERN KS AND SURFACE LOW IS JUST SOUTH OF MHK. TRACK WILL DRAW CIGS BLO 1000FT AGL INTO MHK IN THE NEXT HOUR OR TWO...AND SHOULD FOLLOW INTO TOP/FOE AROUND 09Z. PRECIP TO THE SOUTH IS MORE CELLULAR AND HAVE SWITCHED TO TEMPO GROUP TO ACCOUNT FOR THIS. LEFT STRATIFORM PRECIP OVER MHK BEHIND THE LOW WITH IFR CIGS ALL SITES UNTIL 15Z. CIGS LIFT TO VFR AND WINDS PICK UP AS STRONG PUSH FROM COLD FRONT MOVES IN THE AREA. DROPPED THE GUSTS LATE IN THE DAY AND SCATTERED OUT CIGS. 67 && .PREV DISCUSSION... /ISSUED 302 PM CST MON NOV 23 2009/ DISCUSSION... SHORT TERM (THROUGH TUESDAY)... THE 19Z WATER VAPOR SATELLITE IMAGERY SHOWED AN UPPER LEVEL TROUGH DIGGING SOUTHEAST ACROSS CENTRAL HIGH PLAINS. THE 19Z SURFACE MAP SHOWED A COLD FRONT EXTENDING FROM SOUTHEAST NE...SOUTHWEST ACROSS THE WESTERN COUNTIES OF THE CWA...THEN SOUTHWEST ACROSS THE TX PNHDL. NORTH OF THE BOUNDARY ACROSS NORTH CENTRAL KS...LOW CLOUDS AND PATCHY FOG KEPT TEMPERATURES IN THE MID 40S THROUGH THE MID AFTERNOON HOURS. IN THE WARM SECTOR ACROSS NORTHEAST AND EAST CENTRAL KS TEMPERATURES WERE IN UPPER 50S TO AROUND 60. SKIES WERE PARTLY TO MOSTLY SUNNY WITHIN THE WARM SECTOR. TONIGHT AND TUESDAY...THE UPPER TROUGH WILL DIG SOUTHEAST ACROSS THE PLAINS STATES AND AMPLIFY...CLOSING OFF INTO AN UPPER LEVEL LOW ACROSS NORTHWEST KS THIS EVENING THEN TRACKING EAST ACROSS THE NORTHERN HALF OF THE STATE THROUGH TUESDAY MORNING. STRONG FRONTOGENETICAL FORCING WILL DEVELOP WITHIN THE DEFORMATION ZONE ACROSS SOUTHERN NE AND NORTHERN KS...AND A POTENTIAL TROWAL DEVELOPING ON THE NORTHWEST SIDE OF UPPER LOW. MANY OF THE INGREDIENTS ARE THERE TO SUPPORT A HEAVY SNOWFALL ACROSS THE NORTHERN COUNTIES...HOWEVER BOTH THE NAM AND GFS TEMPERATURE PROFILES IN THE SFC TO 850MB LAYER LOOK TOO WARM FOR SNOW...THOUGH DRIER AIR AT THE SFC BEGINS TO ADVECT SOUTHEAST ACROSS THE NORTH CENTRAL COUNTIES AFTER 12Z. THEN SOME OF THE RAIN MAY MIX WITH OR BRIEFLY CHANGE OVER TO SNOW FOR A FEW HOURS BEFORE THE BOUNDARY LAYER TEMPERATURES WARM ENOUGH FOR AN ALL LIQUID FORM THROUGH THE MID AND LATE MORNING HOURS. THERE IS AN OUTSIDE CHANCE IF THE RAIN CHANGES OVER TO A HEAVY WET SNOWFALL FOR AN HOUR OR TWO ACROSS THE NORTH CENTRAL COUNTIES BETWEEN 11Z AND 15Z THERE COULD BE A SLUSHY INCH OR TWO OF SNOW ACCUMULATIONS. ATTM...MY CONFIDENCE IN MEASURABLE SNOWFALL DUE TO THE WARM BOUNDARY LAYER TEMPERATURES HAVE PRECLUDED ME FROM PUTTING ANY SNOW ACCUMULATIONS IN THE FORECAST GRIDS ACROSS NORTH CENTRAL KANSAS. OVERNIGHT LOWS WILL STAY IN THE 33 TO 35 DEGREE RANGE ACROSS NORTH CENTRAL KS...THUS ROADS SHOULD REMAIN ICE FREE. THE NAM MODEL SHOWS 50 TO 150 J/KG OF MUCAPE FROM 6Z TO 12Z TUE...THUS I CANNOT RULE OUT AN ISOLATED THUNDERSTORM ACROSS EAST CENTRAL AND NORTHEAST KS TONIGHT. THE LIMITED INSTABILITY WILL KEEP ANY ISOLATED ELEVATED THUNDERSTORM WEAK EVEN THOUGH 0-6KM VERTICAL WIND SHEAR LOOKS TO BE MODERATELY STRONG. TOTAL QPF ACROSS THE NORTHERN COUNTIES WILL RANGE BETWEEN 0.40 TO 0.60. THE UPPER LOW WILL TRACK EAST AND NORTHEAST ACROSS NORTHERN MO INTO SOUTHEAST IA DURING THE AFTERNOON HOURS OF TUESDAY. THIS SHOULD BRING AN END TO ANY WRAP AROUND RAIN SHOWERS FROM WEST TO EAST ACROSS THE CWA. THE NORTHWEST WINDS WILL INCREASE THROUGH THE MID AND LATE MORNING HOURS TO 15 TO 25 MPH WITH GUSTS OF 25 TO 35 MPH...THEN THE WINDS SHOULD SLOWLY DIMINISH THROUGH THE LATE AFTERNOON HOURS. CLOUDY SKIES AND LOW-LEVEL CAA WILL ONLY ALLOW HIGHS TO REACH THE MID TO UPPER 40S...AND THE NORTHWEST WINDS WILL MAKE IT FEEL EVEN COOLER. GARGAN LONG TERM (WEDNESDAY THROUGH MONDAY)... STRONG SECONDARY SHORTWAVE TROUGH WILL RAPIDLY DROP OUT OF CANADA IN THE WAKE OF THE INITIAL CLOSED LOW. WHILE THIS SYSTEM WILL DYNAMICALLY BE QUITE IMPRESSIVE...MOISTURE WILL BE SIGNIFICANTLY LACKING AS THE FIRST SYSTEM LOOKS TO SCOUR OUT ANY FORM OF DEEP MOISTURE. THUS EXPECT A DRY FRONTAL PASSAGE WITH AN INCREASE IN NORTHWEST WINDS AND SOME STRATOCUMULUS WITH LITTLE TO NO PRECIPITATION. THE AIRMASS BEHIND THIS FRONT WILL BE COOLER WITH 850 TEMPS DROPPING OFF SIGNIFICANTLY INTO THE -5C RANGE. WINDS WILL KEEP THE LOWER ATMOSPHERE MIXED WHICH MAY ACTUALLY KEEP TEMPS A BIT WARMER OVERALL THAN THEY WOULD BE WITH CALM WINDS. UPPER LEVEL RIDGING WILL BUILD BACK INTO THE PLAINS BY FRIDAY AND SATURDAY WITH A BIT OF A WARMING TREND BEFORE THE NEXT POTENTIAL WEATHER MAKER MOVES IN. THERE IS STILL A LOT OF MODEL DISAGREEMENT WITH ENSEMBLE MEMBERS SHOWING SIGNIFICANT DEVIATION...AND QUITE DIFFERENT SOLUTIONS AMONG THE DIFFERENT MID RANGE MODELS. GENERAL CONSENSUS IS THAT A NORTHERN STREAM TROUGH WILL COME OUT OF THE NORTHERN ROCKIES WITH A SECOND PIECE OF ENERGY DROPPING INTO THE SOUTHWEST U.S. AND A FRONT CONNECTING THE TWO DRAPED ACROSS THE PLAINS. HAVE INTRODUCED A SLIGHT CHANCE FOR SHOWERS WITH THE LIKELY FRONTAL PASSAGE DURING THE WEEKEND...BUT THERE IS SOME CONCERN IN TERMS OF MOISTURE RETURN AHEAD OF THE SYSTEM. DO NOT EXPECT A LOT OF PRECIP AT THIS TIME...BUT WILL SURELY SEE COOLER TEMPERATURES ONCE AGAIN. BARJENBRUCH && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$
