000 FXUS63 KTOP 081747 AFDTOP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1147 AM CST SUN NOV 8 2009 .DISCUSSION... UPDATED TO INCLUDE THE 18Z AVIATION DISCUSSION. && .AVIATION... FOR THE 18Z TAFS...VFR CONDITIONS TO START THE PERIOD. NORTHERN ENERGY AND ATTENDANT COLD FRONT WILL DROP INTO NE KS AFTER 00Z. MOISTURE WILL LIFT NORTHWARD AHEAD OF THE FRONT WITH STRONG SOUTHERLY FLOW. MVFR CIGS ALREADY EVIDENT ACROSS OKLAHOMA VIA MORNING VISIBLE SATELLITE IMAGE WILL BEGIN TO IMPACT MHK AFTER 08Z...AND TOP/FOE AFTER 11Z. DELAYED ONSET OF PRECIPITATION...AS COLUMN SHOULD TAKE SOME TIME TO SATURATE...BUT DID INTRODUCE VCSH AT MHK AFTER 08Z NEARER THE DEEP LIFT. FUTURE TAF ISSUANCES WILL BETTER TIME PRECIP...AND POTENTIALLY ADD TO TOP/FOE SOONER WITH PERSISTING WAA THAT MAY SATURATE A DEEP ENOUGH LAYER TO INITIATE RAINFALL SOONER THAN CURRENTLY ANTICIPATED. LUNDE && PREV DISCUSSION... /ISSUED 334 AM CST SUN NOV 8 2009/ DISCUSSION... RECENT IMAGERY FROM WATER VAPOR CHANNEL SHOWING SHORTWAVE TROF MOVING EAST THROUGH THE PACIFIC NORTHWEST WITH ANOTHER UPPER WAVE IN NORTHERN MEXICO. FLOW OVER MUCH OF THE SOUTHERN PLAINS WAS SOUTHERLY WITH UPPER HIGH IN THE SOUTHEAST CONUS...BRINGING HIGH CLOUDS NORTH ACROSS TEXAS. 00Z SOUNDINGS FROM THE SOUTH AND SOUTHWEST SHOW VERY DRY AIR AROUND 850MB...MOVING THIS WAY PER AREA PROFILERS. MODERATE SOUTHERLY FLOW HAS BROUGHT SURFACE DEWPOINTS UP A BIT OVERNIGHT WITH LOW PRESSURE CENTERED OVER EASTERN COLORADO. SOUTH TO SOUTHWEST WINDS WILL INCREASE TODAY AS THE LOW PUSHES NORTHEAST IN RESPONSE TO THE PACIFIC NORTHWEST WAVE. WITH THE DRY AIR MOVING IN FROM THE SOUTHWEST ABOVE THE SHALLOW NEAR-SURFACE MOISTURE...ONLY EXPECTING INCREASING HIGH CLOUDS AS THE DAY PROGRESSES. UPSTREAM SURFACE TEMPS FROM SATURDAY SUPPORT MOS NUMBERS IN THE MIDDLE 70S. COLD FRONT BEHIND THE QUICKLY MOVING NORTHERN WAVE WILL PUSH INTO THE AREA TONIGHT AND FINALLY EXIT THE AREA LATE MONDAY AFTERNOON. LIFT ABOVE THE FRONT WILL PERSIST THROUGH MUCH OF THE PERIOD...BUT MOISTURE WILL INITIALLY BE LACKING GIVEN AFOREMENTIONED CONDITIONS. MODELS ARE CONSISTENT IN PRODUCING LIGHT PRECIPITATION ALONG THE BOUNDARY LATE TONIGHT...BUT HAVE KEPT POPS ON THE LOW SIDE GIVEN A LACK OF UPPER SUPPORT AND THE DRYNESS OF THE AIRMASS. INSTABILITY IS A BIT DEEPER THAN EARLIER PROGS INDICATED...AND WILL GO AHEAD WITH A THUNDER MENTION MONDAY. NOT EXPECTING HEAVY PRECIPITATION AMOUNTS GIVEN THE LACK OF STRONG FORCING...BUT CLOUDS AND SHOWER ACTIVITY MAY BE RATHER PERSISTENT AND LIMIT DIURNAL RANGES IN TEMPERATURES TO AROUND 10 DEGREES /PERHAPS EVEN LESS/...AND WENT BELOW MOS HERE. UPPER TROFFING DEVELOPING NEARBY MONDAY NIGHT INTO TUESDAY RESULTS FROM A LARGE SCALE PATTERN CHANGE...WITH PACIFIC JET SHIFTING NORTH INTO THE GULF OF ALASKA FORCING DOWNSTREAM CHANGES. THE NAM IS THE SLOW/WEST OUTLIER WITH THE TROF MOVING OUT ON TUESDAY...AND FAVORED THE FASTER AND THUS DRIER ECMWF AND GFS GIVEN THEIR HEMISPHERIC DOMAINS. MAV HIGHS SEEM A BIT WARM THOUGH GIVEN GFS FORECAST SOUNDINGS FOR MOST LOCATIONS. LOW TEMPERATURES BOTH MONDAY NIGHT AND TUESDAY NIGHT WERE BUMPED UP WITH AIRMASS A BIT MORE MOIST THAN EARLIER ANTICIPATED. 65 && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$