Issued by NWS Topeka, KS
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000 FXUS63 KTOP 230449 AFDTOP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1149 PM CDT WED OCT 22 2008 .UPDATE... UPDATED FOR THE 06 UTC AVIATION. && .DISCUSSION... SEE PREVIOUS DISCUSSION BELOW. && .AVIATION... UPPER LOW AND SFC LOW WILL REMAIN NEARLY STATIONARY ACROSS NORTH CENTRAL KANSAS FOR THE NEXT 24 HOURS. TAF SITES WILL SEE MVFR CEILINGS WITH PERIODS OF LIGHT DRIZZLE OR RAIN THROUGH THURSDAY MORNING. WINDS WILL BE SOUTH TO SOUTHEAST AND WILL INCREASE TO 10 TO 15 KTS THROUGH THE MID MORNING HOURS ON THURSDAY. THERE MAY BE SOME SCT OR BRIEF PERIODS OF BKN IFR CEILINGS LATE TONIGHT THROUGH THURSDAY MORNING. && .PREV DISCUSSION... /ISSUED 352 PM CDT WED OCT 22 2008/ DISCUSSION... A WET AND DREARY DAY ACROSS THE EASTERN HALF OF THE CWA TODAY...WHILE THE WESTERN ZONES ENCOUNTER BREEZY AND COOL NORTHWESTERLY FLOW. TOTAL ACCUMULATIONS FROM THE RADAR RUN FROM BETWEEN HALF AND A QUARTER INCH ALONG AND EAST OF THE TURNPIKE...WITH HIGHER AMOUNTS UP TO TWO INCHES...ALTHOUGH SOME OF THESE SPOTS LIKELY CONTAMINATED WITH SOME LATE NIGHT HAIL. OVERALL STEADY LIGHT TO MODERATE RAINFALL GENERATING SOME PONDING OF WATER AND SOUPY CONDITIONS ACROSS THE AREA BUT NO FLOODING OR TROUBLE AREAS REPORTED. EXPECT RAIN TO CONTINUE ALONG THE BAND OF RICHER THETA E AIR STREAMING NORTHWARD ALONG THE LEADING NOSE OF THE UPPER JET AND VORT MAX. PREICP WILL SLOWLY SHIFT TO THE EAST OVER THE NEXT SEVERAL HOURS. MEANWHILE LAYER OF DRY AIR CONTINUES TO WRAP NORTH AND NORTHWEST IN AND AROUND THE BACK OF THE SYSTEM...AND WILL ALSO CONTRIBUTE TO DIMINISHING RAIN CHANCES OVERNIGHT. SOUNDINGS CONTINUE TO SHOW UPPER LAYER DRYING OUT...AND SURFACE MOISTURE LAYER BECOMNIG INCREASINGLY SHALLOW. UPPER SYSTEM DROPS BACK WESTWARD OVERNIGHT...WITH UPPER LOW OVER WESTERN COUNTIES BY THURS AFTERNOON. SEE ENOUGH LIFT IN THE LOW MOIST LAYER TO GENERATE SCATTERED SHOWERS WEST...WITH DECREASING SHOWERS EAST AND HAVE GRIDS AS SUCH. DONT EXPECT HIGHS TO GO MUCH ABOVE THE 40 MARK NORTHWEST TO LOW 50S SOUTHEAST. SOUNDINGS ALSO INDICATE THAT TEMPERATURES SHOULD STAY WARM ENOUGH ACROSS THE FAR NW TO KEEP PRECIP AS LIGHT RAIN. 67 EXTENDED PERIOD...THURSDAY NIGHT THROUGH WEDNESDAY VERTICALLY STACKED UPPER LOW WILL BE CENTERED OVER CENTRAL KANSAS AT THE BEGINNING OF THE PERIOD. CROSS SECTIONS INDICATE PERIOD OF FAIR VERTICAL MOTION WITHIN THE SATURATED LAYER (SFC-H7) AND CHANCES OF LIGHT RAIN SEEM REASONABLE NORTH AND WEST OF THE LOW CENTER. DRY SLOT WILL EFFECTIVELY LIMIT PRECIPITATION PRODUCTION SOUTH AND EAST OF THE LOW CENTER. WHILE COOLER AIR WILL CONTINUE TO ADVECT INTO THE REGION ON THE BACKSIDE OF THE SYSTEM...CONDITIONS DO NOT APPEAR FAVORABLE FOR SNOW WITHIN THE CWA. TAKING POINT SOUNDINGS ACROSS THE FAR WESTERN CWA...WET BULBING THE TEMPERATURE WITHIN THE LOWEST 1KFT OF THE SFC PRODUCES TEMPERATURES BETWEEN 2C TO 4C. ADDITIONALLY...DRY AIR WILL CONTINUE TO WRAP INTO THE SYSTEM...WITH SEVERAL SOLUTIONS SHOWING FAIRLY DRY RELATIVE HUMIDITY VALUES (~40%) WITHIN THE H5-H7 LAYER...WHICH IS ALSO THE -10C TO -20C LAYER. THIS WILL RESULT IN LITTLE ICE PRODUCTION IN THE DENDRITIC ZONE...FURTHER LIMITING SEEDER-FEEDER AND SNOWFALL POTENTIAL EVEN WITH A COLD SATURATED LAYER FROM THE SFC-H7. OVERALL...WITH WEAK NEAR-SFC INSTABILITY AND VERTICAL MOTION...CHANCES OF LIGHT RAIN WILL BE POSSIBLE THURSDAY NIGHT THROUGH FRIDAY...WITH BEST CHANCES NORTH OF INTERSTATE 70. WITH CLOUDS AND LIGHT PRECIPITATION...MAXIMUM TEMPERATURES WILL BE KEPT DOWN ON FRIDAY. SKIES WILL CLEAR FRIDAY NIGHT INTO SATURDAY MORNING. H85 TEMPERATURES WILL WARM 10C WITHIN 24 HOURS FROM 00Z SAT TO 00Z SUN WITH AFTERNOON TEMPERATURES MODERATING SATURDAY AFTERNOON INTO THE LOWER 60S. A LARGE UPPER LOW AND ACCOMPANYING COLD FRONT WILL DIVE INTO THE CENTRAL CONUS ON SUNDAY. VERTICAL MOISTURE PROFILES ARE QUITE DRY SO DRY WEATHER IS EXPECTED WITH THE FRONTAL PASSAGE. A STRONG PRESSURE GRADIENT ALONG WITH AFTERNOON MIXING WILL RESULT IN BREEZY NORTHWEST WINDS WITH GUSTS TO 30 KTS UPON THE PASSAGE OF THE FRONT. WITH MOSTLY CLEAR SKIES AND STRONG COLD AIR ADVECTION...MAY SEE NEAR FREEZING TEMPERATURES MONDAY MORNING. OTHERWISE...NORTHWEST FLOW WILL PERSIST THROUGH THE REMAINDER OF THE EXTENDED PERIOD WITH DRY CONDITIONS EXPECTED. BLAIR && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ GARGAN
