294 
FXUS63 KTOP 280926
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
325 AM CST THU FEB 28 2013

.DISCUSSION...
09Z WATER VAPOR SHOWS AN EXPANSIVE UPPER LOW FROM THE THE TN VALLEY 
INTO NEW ENGLAND...AND ANOTHER WAVE APPROACHING THE PACIFIC 
NORTHWEST. IN BETWEEN OVER THE NORTHERN PLAINS WAS SOME WEAK SHEAR 
AREAS. SFC OBS SHOW A DECENT PRESSURE GRADIENT ACROSS EASTERN KS 
WITH LOW PRESSURE IN THE GREAT LAKES AND RIDGING ALONG THE LEE OF 
THE ROCKIES. 

FOR TODAY THROUGH FRIDAY...THE OVERALL PATTERN DOES NOT CHANGE MUCH 
AS IT BECOMES MORE AMPLIFIED WITH UPPER RIDGING OVER THE WEST COAST 
AND THE CLOSED UPPER LOW OVER THE NORTHEAST. THEREFORE THE FORECAST 
IS ONE OF PERSISTENCE FOR THE MOST PART. MODELS SHOW HIGH RELATIVE 
HUMIDITIES WITHIN THE BOUNDARY LAYER THIS AFTERNOON AND FRIDAY AS 
LOW LEVEL LAPSE RATES STEEPEN UP ALMOST TO THE DRY ADIABAT. SO IN 
THE SHORT TERM THE CONCERN IS WHETHER THERE COULD BE SOME FLURRIES 
OR SPRINKLES THIS AFTERNOON AND AGAIN FRIDAY. CONFIDENCE IS LOW FOR 
TODAY SINCE THERE IS NO REAL SIGN OF FORCING AND ANY TRACE PRECIP 
WOULD BE DRIVEN BY LOW LEVEL INSTABILITY. CONFIDENCE IS NOT MUCH 
BETTER FOR FRIDAY...BUT THERE ARE SIGNS OF THE WEAK SHEER AXIS 
ACROSS THE NORTHERN PLAINS MOVING THROUGH EASTERN KS WITH SOME WEAK 
LOW LEVEL ISENTROPIC LIFT. WITH THIS IN MIND CONTINUED WITH A SLIGHT 
CHANCE FOR FLURRIES MAINLY FRIDAY AFTERNOON. 

WAS A LITTLE SURPRISED THAT YESTERDAYS HIGHS MANAGED TO MAKE IT INTO 
THE 40S WITH NORTH WINDS AND SNOW ON THE GROUND. SO TODAYS FORECAST 
HIGHS IN THE MID 30S ARE REALLY DEPENDENT ON THE LOW CLOUDS HANGING 
IN THROUGH THE AFTERNOON. IF THE SUN IS ABLE TO BREAK OUT...HIGHS 
COULD AGAIN WARM TO AROUND 40. FOR FRIDAY THERE SHOULD BE A LITTLE 
STRONGER COLD AIR ADVECTION AS MODELS SHOW 925 TEMPS COOLING AS THE 
SYNOPTIC PATTERN AMPLIFIES. HAVE LOWS IN THE LOWER AND MID 20S FOR 
TONIGHT WITH THE COLD AIR ADVECTION PICKING UP A LITTLE...BUT AGAIN 
IF THE STRATUS REMAINS OVER THE AREA THIS MAY END UP BEING A LITTLE 
TO COOL.

SATURDAY AND SUNDAY SHOULD BE DRY WITH SKIES FINALLY SCATTERING OUT 
AS THE UPPER LEVEL RIDGE MOVES OVERHEAD. SATURDAY MORNING COULD BE A 
DAY TO WATCH OUR FOR FOG DEVELOPMENT. MODELS INDICATE THE A WEAK 
RIDGE AXIS WILL PROPAGATE OVER EASTERN KS WITH LESS CLOUD COVER. 
GIVEN AMPLE BOUNDARY LAYER MOISTURE FROM THE SNOW MELT...CONDITIONS 
MAY BE FAVORABLE FOR FOG IF THE BOUNDARY LAYER DECOUPLES. MODELS 
SHOW WARM AIR ADVECTION MOVING IN A LITTLE FASTER. THIS COMBINED 
WITH THE EXPECTATION FOR MORE INSOLATION HAS LED TO RAISING FORECAST 
HIGHS FOR SATURDAY AND SUNDAY. ALTHOUGH THEY ARE STILL BELOW CLIMO 
WHICH IS AROUND 50 DEGREES. 

THE MEDIUM RANGE MODELS CONTINUE TO BRING A DECENT LITTLE WAVE 
ACROSS THE PLAINS MONDAY AND MONDAY NIGHT. WHILE THE BEST FORCING 
LOOKS TO REMAIN NORTH OF THE AREA...THE ECMWF TREND OF SLIGHTLY 
FURTHER SOUTH WITH THE TRACK OF THE WAVE LEAVES ENOUGH UNCERTAINTY 
IN THE FORECAST TO MAINTAIN SOME SLIGHT CHANCE POPS FOR MONDAY 
NIGHT. MOISTURE RETURN REMAINS IN QUESTION AS SOME MODELS SUGGEST 
THE LOW LEVEL JET WILL VEER TO THE SOUTHWEST TAKING THE DEEPER 
MOISTURE INTO MO. THIS IS WHY THE FORECAST REMAINS DRY FOR MONDAY AS 
THE SURFACE FRONT MOVES THROUGH. BY TUESDAY MODELS SHOW RIDGING AND 
SUBSIDENCE TAKING OVER AND LASTING THROUGH WEDNESDAY. SO HAVE A DRY 
FORECAST WITH TEMPS MODERATING ONCE AGAIN BY WEDNESDAY. 

WOLTERS

&&

.AVIATION...
MVFR CIGS MOVING SOUTH ALONG THE MISSOURI RIVER AND INTO NORTHEAST 
KANSAS. EXPECT MVFR CIGS AT TOP AND FOE BY 07Z AND AT MHK BY 09Z. 
KEPT THE MVFR CIGS IN UNTIL MID AFTERNOON THEN TRANSITIONED TO VFR. 
VSBYS SHOULD REMAIN VFR THROUGH THE PERIOD AS THE LOWER BOUNDARY 
LAYER WILL REMAIN MIXED WITH NORTHWEST WINDS AROUND 11 KTS.

53

&&

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

&&

$$