FXUS63 KIND 240448
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1145 PM EST WED DEC 23 2009
.AVIATION DISCUSSION...FOR THE 06Z TAFS
MAIN PROBLEM FOR AVIATION WILL BE INCREASING WINDS BEGINNING AFTER
SUNRISE THURSDAY THEN RAIN CHRISTMAS EVE. STRONG LOW PRESSURE IN
EXTREME NORTHEAST TEXAS WILL FURTHER STRENGTHEN AS IT MOVES INTO
IOWA THURSDAY EVENING. TAFS WILL BEGIN WITH A FLOW OF DRY AIR IN LOW
LAYERS CONTINUING INTO THE AREA. THIS WILL KEEP VFR CONDITIONS. SOME
ISOLATED LIGHT SHOWERS IN THE LAF AND HUF AREA SHOULD NOT DECREASE
VISIBILITIES MUCH. AS THE LOW MOVES NORTH THE PRESSURE GRADIENT WILL
INCREASE. AFTER 14Z SURFACE WINDS WILL BEGIN TO GUST TO 20 TO 25 KTS
WITH WINDS AT 15000 FEET AT 35 KTS. WINDS WILL CONTINUE TO INCREASE
DURING THE DAY. THERE IS AN INVERSION THAT WILL LIMIT THE HIGH WINDS
FROM COMPLETELY REACHING THE SURFACE DURING THE DAY. THERE IS A
SHARP CHANGE FROM VFR TO MVFR CONDITIONS. THESE MVFR CONDITIONS WILL
BEGIN TO MOVE INTO THE AREA AFTER 00Z. THE INVERSION WILL BREAK DOWN
ALLOWING STRONG WINDS ALOFT TO REACH THE SURFACE. AFTER 00Z WINDS
COULD GUST TO 35 KTS.
&&
.SHORT TERM UPDATE...
TEMPERATURES THIS EVENING RANGE FROM 30 DEGREES AT MUNCIE TO NEAR 50
DEGREES DOWN AROUND KNOX COUNTY. GIVEN THAT WINDS ARE STILL ESELY
ACROSS THE FORECAST AREA...SEE NO REASON TO ADJUST TEMPERATURES FOR
TONIGHT. MUCH OF THE AREA IS STILL UNDER CONTROL OF HIGH PRESSURE
OVER SERN ONTARIO WHICH IS GIVING US RECYCLED COLD AIR FROM CANADA.
ALSO...WITH TEMPERATURES IN THE 30S AND 40S...SURFACE DEW POINTS
RANGE FROM THE MID 20S IN THE NERN PART OF THE FORECAST AREA TO LOW
40S SOUTHWEST. LATEST BUFKIT DATA FROM THE RUC SHOWS KIND WET-BULB
ZERO NEAR 32...SO THAT IS ANOTHER REASON TO LEAVE FORECAST
TEMPERATURES WELL ENOUGH ALONE TONIGHT.
STORM SYSTEM IN THE SOUTHERN PLAINS STILL ORGANIZING AT THIS TIME
WITH ONE LOW OVER THE RED RIVER BETWEEN OKC AND DFW..AND ANOTHER IN
THE MIDDLE RIO GRANDE VALLEY. THESE LOW SHOULD MEET UP TOMORROW
OVER CENTRAL TX THEN MOVE NNEWD BRINGING MUCH WARMER AIR TO OUR AREA
AND A BETTER CHANCE FOR RAIN.
&&
.DISCUSSION...
FORECAST FOCUS IS ON POPS/PRECIPITATION TYPE EARLY IN THE FORECAST
THEN ON WINDS.
AT 18Z SURFACE LOW PRESSURE WAS ACROSS EASTERN KANSAS WITH A WARM
FRONT EXTENDING EAST INTO SOUTHERN KENTUCKY. ACROSS THE FORECAST
AREA...FREEZING RAIN WAS EXITING THE NORTHEASTERN PART OF THE AREA
/WHERE TEMPERATURES REMAINED JUST BELOW FREEZING/. RAIN WAS ACROSS
NORTHWESTERN AREAS.
MODELS IN FAIR AGREEMENT THIS RUN. NAM APPEARS TOO COLD WITH SURFACE
TEMPERATURES /COMPARED TO WHAT IS GOING ON NOW/...SO WENT CLOSER TO
GFS THERE. FOR THE MOST PART THOUGH WENT WITH A MODEL BLEND.
CURRENT RAIN ACROSS THE AREA SHOULD MOVE OUT BY TONIGHT...BUT
CONTINUED ISENTROPIC LIFT WILL KEEP THE THREAT AROUND ALL NIGHT
LONG. CURRENT RADAR SHOWS RAIN MOVING NORTHEAST OUT OF SOUTHERN
MISSOURI...AND THIS LOOKS TO REACH THE FAR WESTERN AREA.
MEANWHILE...A DRY EASTERLY SURFACE FLOW WILL TRY TO EAT AWAY AT RAIN
THAT MOVES EAST. PUTTING THIS ALL TOGETHER LEADS TO A POPS GRADIENT
OF LOW CHANCE POPS IN THE EASTERN AREA TO LIKELY OR HIGHER POPS
ACROSS THE FAR WESTERN FORECAST AREA. TEMPERATURES SHOULD COOL
ENOUGH ACROSS THE NORTHEASTERN AREAS TO KEEP CHANCES OF FREEZING
RAIN AROUND THERE. COVERAGE OF PRECIPITATION SHOULD BE LOW ENOUGH TO
NOT CAUSE ANY SIGNIFICANT PROBLEMS. WITH THE NAM LOOKING TOO
COLD...WENT CLOSER TO THE WARMER MAV NUMBERS.
AS THE SYSTEM GETS CLOSER TO THE AREA ON THURSDAY FORCING WILL
INCREASE DURING THE DAY AS CAN BE SEEN IN THE ISENTROPIC AND
Q-VECTOR CONVERGENCE FORECASTS. THIS FORCING COMBINED WITH THE
MOISTURE FLOWING INTO THE AREA FROM THE SOUTH WILL LEAD TO LIKELY OR
HIGHER POPS BY AFTERNOON ALL AREAS. TEMPERATURES WILL BE COLD ENOUGH
AT THE START OF THE DAY FOR A CONTINUED THREAT OF SOME LIGHT
FREEZING RAIN ACROSS NORTHEASTERN SECTIONS OF THE AREA...BUT THIS
ALSO OCCURS AT THE TIME OF THE LOWER CHANCES FOR PRECIPITATION. THUS
NOT EXPECTING ANY SIGNIFICANT PROBLEMS AT THE MOMENT. BY MID TO LATE
MORNING THE SURFACE TEMPERATURES SHOULD BE WARM ENOUGH FOR RAIN.
MET CONTINUES TO LOOK TOO COOL MANY PLACES. AFTER COLLABORATION
ENDED UP WITH TEMPERATURES IN BETWEEN MAV AND MET FOR HIGHS.
THURSDAY NIGHT A 70KT 850 JET MOVES INTO THE AREA. FORCING AND
PLENTIFUL MOISTURE WILL LEAD TO CATEGORICAL POPS ALL AREAS. QPF
AMOUNTS COULD BE AROUND 1 INCH WHICH MAY LEAD TO SOME FLOODING
ISSUES. WILL CONTINUE TO MENTION IN HWO. SHOULD GET BREEZY THURSDAY
NIGHT WITH SURFACE PRESSURE GRADIENT TIGHTENING AND STRONG WINDS NOT
TOO FAR ABOVE THE SURFACE. QUESTION IS HOW WILL THE INVERSION WILL
PROTECT THE SURFACE FROM THE WINDS. AT THE MOMENT BELIEVE THAT THE
INVERSION SHOULD BE STRONG ENOUGH TO KEEP ANY GUSTS BELOW ADVISORY
CRITERIA...AND GRADIENT WINDS SHOULD AVERAGE JUST BELOW. WILL KEEP
AN EYE ON...ESPECIALLY ACROSS SOUTHERN AREAS WHERE MORE MIXING MAY
OCCUR.
DRY SLOT MOVES IN ON CHRISTMAS AND SHOULD CUT OFF BULK OF
PRECIPITATION AS COLDER AIR MOVES IN. WILL KEEP LOW POPS AND RAIN TO
SNOW AS IN PREVIOUS FORECASTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...CS
AVIATION...HAINES
SHORT TERM...MCCARTHY
