000
FXUS63 KIND 061045
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
545 AM EST TUE JAN 6 2009
.AVIATION...DISCUSSION FOR 12Z TAFS.
A WINTRY MIX HAS SPREAD NE ACRS SCNTRL INDIANA EARLY THIS MRNG
AHEAD OF A WARM FNT ACRS THE TN VLY AND GULF STATES. ACARS SOUNDINGS
WERE INDICATING A SLIGHTLY WARMER LYR ALOFT THAN THE RUC OR NAM
SOUNDINGS. THIS HAS RESULTED IN MOST OF THE PRECIP REPORTS THIS MRNG
BEING FREEZING RAIN. THIS TREND SHOULD CONT AS MODELS SHOW THIS LYR
WARMING EVEN MORE THIS AFTERNOON ALONG WITH DRYING IN THE SNOW
GROWTH LYR. THE EXCEPTION COULD BE AT LAF THIS MRNG WHERE SOUNDINGS
FAVOR STARTING IT OUT AS FREEZING RAIN OR SNOW. MVFR OR IFR CONDS
EXPECTED TO PERSIST THROUGH THE PD BASED ON MODEL TIME SECS AND LOW
LVL RH PROGS. PRECIPITATION SHOULD BE CONCENTRATED E OF THE TAF
SITES BY THIS AFTERNOON AS GREATEST OVERRUNNING AND MOISTURE IS
EXPECTED TO SHIFT E. WL ONLY EXPECT LGT SN OR FREEZING DRIZZLE TNGT
AHEAD OF AN APRCHG UPR TROF AS TEMPS COOL ALOFT. WINDS WL NOT BE AN
ISSUE AS THEY SHOULD STAY BLW 10KTS WITH WEAK SFC PRES GRADIENT.
&&
.DISCUSSION...FORCAST FOCUS IS ON CURRENT WINTER WX IN THE SHORT
TERM.
THE NAM12 IS CURRENTLY DOING THE BEST JOB OF DEPICTING WHERE PRECIP
AREAS ARE AND WILL USE THAT AS A GUIDE. NAM12 SOUNDINGS WERE ALSO
DOING OK WHEN COMPARED WITH AMDAR DATA BUT WERE A LITTLE ON THE WARM
SIDE /ALTHOUGH LESS SO THAN OTHER MODELS/.
HAVE EXPANDED THE WINTER WX ADVISORY TO INCLUDE THE REMAINDER OF THE
CWA MOSTLY BECAUSE OF THE IMPACT THAT FZRA/FZDZ WILL HAVE ON TRAVEL.
AREA OF PRECIP WAS JUST GETTING INTO THE FAR SOUTHERN CWA AT 07Z.
THIS AREA IS EXPECTED TO CONTINUE TO EXPAND AS A CONSTANT FEED OF
MOISTURE STREAMS IN FROM THE PACIFIC. AS HEIGHTS RISE IN RESPONSE
TO THE DEEPENING H5 TROF OVER TX/MEXICO SOME WARMING ALOFT WILL
OCCUR AND WILL HELP PRODUCE FREEZING RAIN THROUGH A GOOD PORTION OF
CENTRAL INDIANA. AS THE UPPER SYSTEM MOVES EAST A SURFACE LOW WILL
MOVE NORTH FROM THE DEEP SOUTH. THIS WILL CONTINUE TO PUSH TEMPS
ABOVE FREEZING. BY THIS AFTERNOON...SURFACE TEMPS RISE ABOVE
FREEZING AND BUFKIT SOUNDINGS SHOW ENOUGH WARMING TO TRANSITION TO
RAIN...MOSTLY FOR AREAS ALONG AND SOUTH OF INTERSTATE 70.
FOR THE FAR NW CWA...BUFKIT SOUNDINGS INDICATE NO ICE CRYSTALS IN
THE CLOUD LAYER YET THE SOUNDING IS BELOW FREEZING SO HAVE GONE WITH
FREEZING DRIZZLE THERE FOR THIS AFTERNOON. NAM12 KEEPS THIS AREA
PRECIP FREE FOR MOST OF THE DAY ANYWAY SO WILL KEEP LOW CHANCE
POPS.
BY TONIGHT THE SURFACE SYSTEM/UPPER TROF WILL BE MOVING ACROSS THE
STATE AND RAIN WILL TRANSITION BACK TO A BRIEF PERIOD OF FREEZING
RAIN THEN SNOW. THE FAR SOUTH WILL REMAIN RAIN INTO THE EVENING.
AFTER MIDNIGHT THE MAJORITY OF THE CWA SHOULD BE BACK TO SNOW. SNOW
AMOUNTS WILL BE LIGHT.
ON WEDNESDAY TEMPS WILL HOVER AROUND OR SLIGHTLY ABOVE FREEZING.
HAVE PUT IN AN AREA OF RA/SN WHICH WILL BE MORE LIKE SNOW CHANGING
TO RAIN. POPS ARE STILL IN THE CHANCE CAT AND QPF WILL BE VERY
LIGHT.
AS THE H5 TROF CONTINUES TO DEEPEN AND MOVE EAST A SHOT OF COLD
CANADIAN AIR MOVES INTO CENTRAL INDIANA. TEMPS ON THURSDAY WILL
HOVER MOSTLY IN THE 20S.
NO CHANGES MADE TO THE DAY 3-7 PERIOD.
&&
.AVIATION...DISCUSSION FOR 06Z TAFS
LIGHT PRECIPITATION ALONG AND SOUTH OF OHIO RIVER WILL BEGIN
SPREADING NORTH INTO CENTRAL INDIANA VERY LATE TONIGHT AND TUESDAY
MORNING AS WEAK LOW PRESSURE OVER THE LOWER MISSISSIPPI VALLEY MOVES
NORTHEAST TO OHIO BY MIDNIGHT TOMORROW. MAIN CHANGE WITH THIS
FORECAST WILL BE TO SLOW DOWN THE DETERIORATION OF CIGS AND VSBY A
FEW HOURS AS THERE IS STILL LOTS OF DRY AIR IN PLACE. EVENTUALLY
THE IFR CONDITIONS WILL WIN OUT.
MODEL SOUNDINGS SHOW SOME WARMING ALOFT SO PRECIP MAY BRIEFLY START
OUT AS SNOW...THEN CHANGE TO LIGHT FREEZING RAIN AND EVENTUALLY
DRIZZLE BY 16-18Z. KLAF MAY STAY COLD ENOUGH ALOFT SO PRECIP THERE
WOULD BE MOSTLY VERY LIGHT SNOW. AS LOW PRESSURE MOVES EAST OF
INDIANA ANY REMAINING PRECIP WILL GRADUALLY CHANGE OVER TO SCT LIGHT
SNOW SHOWERS OR FLURRIES TUESDAY NIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR ALL OF CENTRAL INDIANA.
&&
$$
PUBLIC...SALLY
AVIATION...MK
