FXUS63 KIND 280230
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
930 PM EST FRI NOV 27 2009
.UPDATE...
DROPPED SKY COVER FROM MOSTLY CLEAR TO CLEAR ACROSS THE AREA FOR THE
REST OF TONIGHT ON BASED ON SATELLITE LOOP. ALSO HAVE DROPPED
MINIMUM TEMPERATURES ACROSS THE AREA BY A FEW DEGREES AS
TEMPERATURES IN SEVERAL SPOTS HAVE ALREADY FALLEN TO/BELOW EARLIER
FORECAST MINIMUMS. WITH EXPECTED WARM ADVECTION RAMPING UP OVERNIGHT
HAVE ONLY GONE SLIGHTLY LOWER THAN CURRENT TEMPERATURES AND REALLY
EXPECT THINGS TO REMAIN STEADY OR EVEN INCREASE A BIT AFTER MIDNIGHT.
&&
.AVIATION...DISCUSSION FOR THE 00Z TAFS
VFR CONDITIONS THROUGH THE TAF PERIOD. TAFS WILL START OUT WITH A
RIDGE OF HIGH PRESSURE EXTENDING FROM THE GULF COAST TO THE GREAT
LAKES. AT THE END OF THE TAF THE HIGH WILL MOVE TO THE EAST COAST.
&&
.PREV DISCUSSION...A SURFACE RIDGE OF HIGH PRESSURE WAS FOUND ACROSS
CENTRAL ILLINOIS EXTENDING NORTH TO WISCONSIN. LOW PRESSURE WAS
CENTERED JUST EAST OF CAPE COD AND WAS KEEPING A COOL CYCLONIC FLOW
ACROSS THE NORTHEAST PART OF THE COUNTRY. SATELLITE IMAGES SHOW THE
CLOUDS ACROSS CENTRAL INDIANA BEGINNING TO WANE AS THE SURFACE FLOW
BECOMES MORE ANTICYCLONIC AS THE RIDGE BUILDS EAST.
MAIN FORECAST CHALLENGE TODAY WILL BE TEMPS.
NAM/GFS ARE IN PRETTY GOOD AGREEMENT AND WILL USE A BLEND. SURFACE
RIDGE EXPECTED TO BUILD ACRS INDIANA TONIGHT...CLEARING SKIES.
HOWEVER 300K ISENTROPIC SURFACE SHOWS DECENT UPGLIDE TONIGHT WITH
ASSOCIATED WARM AIR ADVECTION. DEWPOINTS ARE EXPECTED TO BE IN THE
MIDDLE AND UPPER 20S WITH CLEAR SKIES AND LIGHT SOUTH WINDS. WITH
THESE COUNTERACTING FORCES OCCURRING...AND MAVMOS LOOKING VERY
REASONABLE WILL STICK CLOSE TO MAVMOS.
RIDGING WILL BE BUILDING ACROSS INDIANA AND THE REGION ON SATURDAY.
TIME HEIGHT SECTIONS SHOW A DRY COLUMN WITH SUBSIDENCE ALONG WITH A
STRONGLY POSITIVE CU RULE. WITH PLENTY OF SUN AND H8 TEMPS STARTING
OUT THE DAY NEAR 7C...WL LEAN TO THE WARMER SIDE OF MAVMOS FOR HIGHS.
ON SATURDAY NIGHT A COLD FRONT WILL BEGIN TO DROP OUT OF THE UPPER
MIDWEST AND APPROACH INDIANA. INITIAL IMPACTS FROM THIS SYSTEM ON
SATURDAY NIGHT WILL MAINLY JUST BE INCREASING CLOUDS...AS THE VERY
DRY COLUMN WILL TAKE SOME TIME TO MOISTEN UP. WILL AGAIN LEAN TOWARD
THE WARMER SIDE OF THE MAVMOS GIVEN THESE TRENDS.
FORECAST SOUNDINGS FINALLY BEGIN TO SATURATE ON SUNDAY AS THE COLD
FRONT PUSHES ACROSS INDIANA. LOWER LEVEL Q VECTORS SHOW GOOD
CONVERGENCE AND THE 300K ISENTROPIC SURFACE ALSO SHOWS GOOD LIFT.
WILL TRY AND CONCENTRATE POPS TO MAINLY THE AFTERNOON HOURS AND
CONFIDENCE IS GROWING SUCH THAT WE SHOULD BE ABLE TO RAISE MAVMOS
POPS BY 10 TO 20 PERCENT. HOWEVER WITH EXPECTED CLOUDS AND
PRECIPITATION WILL GO AT OR BELOW MAVMOS TEMPS.
BEST CHANCES FOR RAIN WILL BE ON SUNDAY NIGHT AS THE SURFACE FRONT
PASSES ALONG WITH THE UPPER TROUGH. WL AGAIN RAISE POPS BY 10
PERCENT BUT WILL STICK CLOSE ON THE TEMPS GIVEN THE MANY ELEMENTS IN
PLAY INCLUDING RAIN CHANCES...CLOUDS AND COLD AIR ADVECTION.
AS FOR THE EXTENDED...A SERIES OF FRONTAL SYSTEMS APPEAR TO PUSH
ACROSS THE REGION LATE NEXT WEEK. MONDAY AND TUESDAY APPEAR TO START
OUT THE WORKWEEK DRY AS HIGH PRESSURE OVER THE SOUTHERN STATES KEEPS
A MILD...QUICK AND WESTERLY PACIFIC FLOW ACROSS INDIANA. HOWEVER ON
WEDNESDAY THE ECMWF AND GFS SUGGEST A STRONG COLD FRONT DROPPING OUT
OF CANADA. AT THIS TIME MOISTURE WILL BE SUSPECT WITH THIS SYSTEM
SINCE THE GULF NEVER REALLY OPENS UP...HOWEVER THE DYNAMICS SEEM
STRONG ENOUGH THAT POPS STILL SEEM WARRANTED.
ECMWF AND GFS ALSO SUGGESTING A STRONG LOW PUSHING OUT OF THE GULF
ON THURSDAY AND PUSHING NORTHEAST ON FRIDAY...ALLOWING FOR A COLD
CYCLONIC FLOW OF AIR ACROSS INDIANA. ECMWF EVEN HINTS AT H8 TEMPS
NEAR -10C WHILE GFS IS LESS AGGRESSIVE WITH H8 TEMPS NEAR 0C. EITHER
WAY A COLDER TREND APPEAR TOWARD THE END OF THE NEXT WORKWEEK...AND
WITH CYCLONIC FLOW IN PLACE...TRAPPING OF STRATUS AND VERY LIGHT
PRECIPITATION SEEMS QUITE REASONABLE.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...PUMA
AVIATION...HAINES
UPDATE...CP
