FXUS63 KIND 110922
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
430 AM EST FRI DEC 11 2009
.AVIATION...DISCUSSION FOR THE 12Z TAFS.
LARGE ARCTIC HIGH PRESSURE CENTERED OVER THE TENNESSEE RIVER VALLEY
WILL CONTINUE TO PROVIDE VFR CONDITIONS AT THE TAF SITES FOR THE
NEXT 24 TO 30 HOURS. TIME HEIGHT SECTIONS ARE VERY DRY WITH WITH
SUBSIDENCE. FORECAST SOUNDINGS SHOW RIDICULOUSLY HIGH CONVECTIVE
TEMPERATURES...THUS NO CU AND ONLY THE PASSING CIRRUS CLOUD ARE TO
BE EXPECTED. PRESSURE GRADIENT WILL CONTINUE TO RELAX AND EXPECT
FEWER TO NO GUSTS TODAY...ESPECIALLY SOUTH.
&&
.DISCUSSION...
SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER THE SOUTHEAST AND A LOW
THAT STRETCHES FROM THE ST JAMES BAY TO THE NORTHERN PARTS OF THE
CANADIAN ATLANTIC COAST. IR SATELLITE LOOP SHOWS FEW TO SCATTERED
CIRRUS TOPPING THE RIDGE AND FLOWING INTO THE SOUTHERN PART OF THE
FORECAST AREA BUT OTHERWISE SKIES ARE CLEAR. TEMPERATURES ARE IN THE
UPPER TEENS WITH DEWPOINTS MAINLY IN THE SINGLE DIGITS AND WINDS OF
5 TO 10 KTS OUT OF THE SOUTHWEST.
FORECAST FOCUS IS ON POPS AND PRECIPITATION TYPE SATURDAY NIGHT AND
SUNDAY. MODELS ARE IN GOOD AGREEMENT AND WILL USE A BLEND.
HIGH PRESSURE WILL KEEP DRY WEATHER AROUND UNTIL SATURDAY NIGHT.
SUNNY SKIES EXPECTED TODAY AND CLEAR TO MOSTLY CLEAR TONIGHT WITH
HIGH PRESSURE MOVING ACROSS THE SOUTHEASTERN STATES. FOR HIGHS WENT
CLOSER TO THE COLDER MET. THINK THE MAV IS OVERDOING WARMING BASED
ON H8 TEMPS AND UPSTREAM HIGHS FROM YESTERDAY. FOR TONIGHT/S LOWS
FAVORED THE WARMER MET NUMBERS AS THESE ARE CLOSER IN LINE WITH LOWS
WE/RE SEEING THIS MORNING AND SEE NO REASON WHY TONIGHT SHUD BE
COLDER WITH SKIES BEING SIMILAR AND SOME WARM ADVECTION JUST
STARTING ON THE BACK SIDE OF THE HIGH.
CLOUDS SHOULD INCREASE A BIT ON SATURDAY AND THIS WILL INHIBIT
WARMING SOME SO WENT NEAR THE COOLER MET TEMPERATURES. BY SATURDAY
NIGHT ISENTROPIC LIFT GETS GOING AND CONDENSATION PRESSURE DEFICITS
ARE REACHED SOMEWHERE IN THE 0 TO 6Z TIMEFRAME. SOME WEAK UPPER
FORCING SHOWING UP IN Q VECTOR CONVERGENCE FIELDS AS WELL DURING
THIS TIME. MOISTURE DOES APPEAR SUSPECT HOWEVER AS TIME HEIGHTS DO
NOT SHOW SATURATION THROUGH THE COLUMN BUT ONLY IN LITTLE 200 MB
LAYERS /FIRST HIGH...THEN MIDDLE...THEN LOW LEVEL/. WHILE MAV AND
MET POPS ARE GOING LIKELY AT THIS TIME...DO NOT FEEL CONFIDENT
ENOUGH TO JUMP ON YET. INSTEAD WILL TREND UP TO HIGH CHANCE AND SEE
HOW THINGS LOOK NEXT RUN. AS FAR AS PRECIPITATION TYPE IS
CONCERNED...STILL VERY MUCH UP IN THE AIR. MODELS ARE SHOWING STRONG
ENOUGH WARMING THAT IT COULD BE MOSTLY RAIN...BUT SOUNDINGS ALSO
SHOW THE POSSIBILITY ACROSS MOST OF THE COUNTIES /EXCEPT THE FAR
SOUTH/ OF BEING DRY ENOUGH THAT EVAPORATIONAL COOLING COULD COOL THE
COLUMN AFTER STARTING BRIEFLY AS RAIN OR FREEZING RAIN AND GOING
OVER TO SNOW BEFORE FINALLY WARMING AND MOISTENING UP ENOUGH TO BE
RAIN. SURFACE TEMPERATURES IN THE MODELS DON/T APPEAR TO BE BELOW
FREEZING BUT THEY ARE CLOSE AND WITH THE COLD GROUND AND COLD
CONDITIONS LEADING UP TO THE ARRIVAL OF PRECIPITATION THINK THE
MODELS MAY BE OVERDOING THE SURFACE WARMING. ALL THIS BEING
SAID...HAVE CONTINUED PREVIOUS FORECAST OF RAIN IN THE FAR SOUTH AND
RAIN OR SNOW IN THE CENTRAL AND NORTH. ON SUNDAY Q VECTOR
CONVERGENCE ACTUALLY SHOWS UP STRONGER MOVING THROUGH THE AREA FROM
12 TO 18Z SO BUMPED UP TO CHANCE IN THE EAST AND MAINTAINED SLIGHT
CHANCE IN THE EAST. ALSO ADDED A RAIN SNOW MIX TO THE NORTHERN
COUNTIES BASED ON THE NORTHERN COUNTIES BEING BORDERLINE IN THE
FORECAST SOUNDINGS. KEPT THINGS DRY AFTER 18Z BUT SOUNDINGS DO
INDICATE WEAK POTENTIAL FOR DRIZZLE SO MAY NEED TO ADD THIS LATER.
NO CHANGES MADE TO THE EXTENDED.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...CP
AVIATION...JP
