HAMweather.com Area Forecast Discussion for County Warning Area TOP

Thu, 16 Feb 2012 06:25:11 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1118 PM CST WED FEB 15 2012

...UPDATE TO AVIATION...

.DISCUSSION...

A COMPACT SHORT WAVE TROUGH WAS MOVING ALONG THE OKLAHOMA/KANSAS
BORDER WEDNESDAY AFTERNOON WITH AN ASSOCIATED SURFACE LOW IN
CENTRAL OKLAHOMA MOVING TOWARD SOUTHWEST MISSOURI. GULF MOISTURE
WAS STREAMING NORTH AHEAD OF THIS SYSTEM WITH SURFACE DEWPOINTS IN
THE 50S IN SOUTHEAST KANSAS AND MID 40S IN THE LOCAL FORECAST
AREA. THE MOISTURE ONLY EXTENDS UP TO ABOUT 800 HPA WITH DRIER AIR
ALOFT. THIS MOISTURE PROFILE HAS COUPLED WITH STRONG LIFT
ASSOCIATED WITH THE SYSTEM TO MAINTAIN A BIT OF A FOGGY DAY WITH
PLENTY OF LOW CLOUDS AND OCCASIONAL DRIZZLE/SHOWERS ACROSS THE
AREA. MEANWHILE...A DRIER AIRMASS IS WORKING IN FROM THE NORTH
BEHIND THE SYSTEM...WITH NORTH WINDS ALREADY OVERTAKING THE
AREA...AND THE DRIER SURFACE AIR POISED TO MOVE SOUTH OUT OF
NEBRASKA.

THE MAJORITY OF SHOWERS TODAY HAVE BEEN CONVECTIVE IN NATURE OWING 
TO STEEPER LAPSE RATES IMMEDIATELY ABOVE THE WARM MOIST LAYER. THERE 
HAS BEEN A BIT OF A LULL IN SHOWER ACTIVITY EARLY THIS AFTERNOON BUT 
DEEP CONVECTION HAS INCREASED IMMEDIATELY AHEAD OF THE INCOMING 
SHORT WAVE...EVIDENT ON RADAR AND SATELLITE IMAGERY. THIS SHOWER 
ACTIVITY IS EXPECTED TO MOVE NORTHEAST ACROSS THE FORECAST AREA WITH 
SOME POTENTIAL FOR THUNDERSTORMS...ESPECIALLY SOUTH OF I-70 WHERE 
400+ J/KG OF MUCAPE IS IN PLACE. COULD EVEN SEE SOME SMALL HAIL WITH 
THE STRONGER INDIVIDUAL CELLS. SEVERE WEATHER APPEARS HIGHLY 
UNLIKELY THOUGH.

THE STORM SYSTEM AS A WHOLE WILL PUSH EAST THIS EVENING WITH ANY 
ASSOCIATED PRECIP AND MOISTURE EXPECTED TO MOVE EAST OF THE AREA BY 
MIDNIGHT. THERE APPEARS TO BE SOME POTENTIAL FOR FOG OVERNIGHT AS 
CLEARING SKIES OVERTAKE THE REGION ABOVE A MOIST NEAR-SURFACE LAYER. 
HOWEVER...LOW LEVEL WINDS MAY BE STRONG AND DRY ENOUGH TO PROMOTE 
MIXING AND PREVENT FOG...AND HAVE NOT INCLUDED IT IN THE FORECAST AT 
THIS TIME. OVERNIGHT LOWS WILL DROP BELOW FREEZING OVERNIGHT AND 
THIS MAY SET UP FOR SOME FREEZING OF WET ROADWAYS WITH POTENTIAL TO 
CAUSE HAZARDOUS DRIVING CONDITIONS BY MORNING. TEMPS WILL WARM 
NICELY ON THURSDAY WITH ZONAL FLOW ALOFT...PLENTY OF SUNSHINE...AND 
LIGHT WINDS AS SURFACE HIGH PRESSURE SETTLES OVER THE FORECAST AREA.

BARJENBRUCH

DIFFERENCES BEGIN TO OCCUR ALOFT BY THURSDAY NIGHT IN THE SPLIT 
UPPER FLOW. THE GFS IS THE OPERATIONAL OUTLIER OF BRINGING THE 
SOUTHERN BRANCH UPPER TROF OUT OF THE SOUTHERN ROCKIES AHEAD OF 
NORTHERN BRANCH ENERGY DIVING SOUTHEAST OUT OF CENTRAL CANADA. 
SIDING WITH THE MAJORITY HERE...WHICH KEEPS ANY PRECIP TO THE SOUTH 
FOR FRIDAY NIGHT. HIGH CLOUDS SHOULD SPILL OVER THE ROCKIES AHEAD OF 
THE SOUTHERN SYSTEM THURSDAY NIGHT AND FRIDAY. WESTERLY FLOW WILL 
DEVELOP NEAR THE SURFACE FOR A CONTINUED WARMING TREND FOR 
FRIDAY...BUT COOLER AIR WITH THE NORTHERN PLAINS SYSTEM WILL COME IN 
LATE IN THE DAY. CLEARING SKIES BEHIND THE AFOREMENTIONED SYSTEMS 
EXPECTED FRIDAY NIGHT INTO SATURDAY WITH HIGHS BACK IN THE LOW TO 
MID 40S. 

TROUBLE WITH SPLIT FLOW DEVELOPS AGAIN EARLY NEXT WEEK. AFTER 
LONGWAVE RIDGING PASSES SUNDAY...MODELS AGAIN STRUGGLE WITH HOW 
SHORTWAVE ENERGY WILL MAKE ITS WAY THROUGH THE CENTRAL PORTIONS OF 
THE NATION. MOST RECENT OPERATIONAL MODELS ARE MORE CUT OFF WITH 
TROFFING INTO THE SOUTHWESTERN CONUS...DIFFERING FROM A FASTER AND 
NEGATIVELY-TITLED WAVE SWEEPING THROUGH THE PLAINS. ENSEMBLES STILL 
SHOWING CONSIDERABLE VARIATIONS ON THESE THEMES. PRECIPITATION 
CHANCES WILL BE LOWERED FOR THE SUNDAY NIGHT PERIOD WITH UPPER RIDGE 
JUST EXITING...AND ALSO TEMPERED INTO MONDAY WITH THE WEAKER/SPLIT 
UPPER FLOW TREND. IN KIND...MONDAY APPEARS A BIT WARMER WITH MORE 
PERSISTENT SOUTHERLY WINDS. SOME CHANCE FOR PRECIPITATION WILL 
LINGER INTO MUCH OF THE MIDWEEK WITH A SOUTHERN CONUS WAVE POSSIBLY 
LINGERING. EXPECT MOST PRECIP TO BE RAIN...WITH A FEW HOURS OF 
NEAR-FREEZING TEMPS POSSIBLE AROUND SUNRISE FOR SOME MIXED 
CONCERN....BUT OVERALL ABOVE NORMAL TEMPS ARE LIKELY. 

65

.AVIATION...

EXPECT CONDITIONS TO CONTINUE IMPROVING IN THE OVERNIGHT HOURS.
DRIER AIR WORKING ITS WAY INTO THE TERMINAL SITES IS HELPING TO
ERODE THE LOW STRATUS DECK. CIGS AND VSBY HAVE BEEN ON THE RISE
OVER THE PAST FEW HOURS...SO EXPECT THE TREND TO CONTINUE. EXPECT
ALL SITES TO BE VFR BY 08Z. NO UPSTREAM FOG DEVELOPMENT IN THE
PAST FEW HOURS...SO LOSING CONFIDENCE IN DEVELOPMENT AT THE
TERMINALS.

BYRNE

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