Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 211346
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
945 AM EDT MON APR 21 2014

.UPDATE...

THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 304 AM EDT MON APR 21 2014

SHOWERS WITH EMBEDDED THUNDERSTORMS WILL DEVELOP LATER TODAY AND
CONTINUE TONIGHT AS A COLD FRONT MOVES THROUGH THE OHIO VALLEY.
COOLER DRIER WEATHER RETURNS FOR TUESDAY AND WEDNESDAY AS HIGH
PRESSURE MOVES THROUGH THE REGION. WARMER AND MORE UNSETTLED WEATHER
RETURNS FOR LATE WEEK WITH THE PASSAGE OF ANOTHER COLD FRONT. BEHIND
THE FRONT...COOLER WEATHER WILL RETURN FOR THE WEEKEND.

&&

.NEAR TERM /TODAY/...
ISSUED AT 945 AM EDT MON APR 21 2014

RADAR MOSAIC SHOWS SOME ECHOES OF 20-30 DBZ MOVING INTO KNOX COUNTY
AT 930 AM AND VISIBLE SATELLITE SHOWS A CONVECTIVE NATURE TO THE
CLOUDS ASSOCIATED WITH THESE ECHOES. THUS FAR NO PRECIPITATION HAS
BEEN REPORTED AT THE GROUND UNDER THESE CLOUDS AND WITH DEW POINTS
IN THE MID 40S TO LOW 50S AND A FAIRLY DRY COLUMN THINK CONTINUING
WITH NO MEASURABLE PRECIP TIL AFTER 19Z IS A GOOD IDEA. HOWEVER
CAN/T RULE OUT A FEW SPRINKLES DEVELOPING IN THE SOUTHWEST...SO WILL
GO AHEAD AND ADD A CHANCE FOR SPRINKLES THERE FOR THE NEXT FEW
HOURS. REST OF THE FORECAST IS IN GOOD SHAPE WITH HIGHS IN THE MID
TO UPPER 70S STILL ON TRACK AND HI RES MODELS SHOWING SIMILAR TIMING
TO MEASURABLE PRECIP AS THE GOING FORECAST...AFTER 19Z WITH BEST
CHANCES NOT ARRIVING UNTIL SOMETIME AFTER 0Z.

PREVIOUS DISCUSSION FOLLOWS...

MAIN FOCUS FOR TODAY IS THE APPROACH OF THE UPPER WAVE AND COLD
FRONT TO THE WEST AS LOW PRESSURE OFF THE NORTH CAROLINA COAST
FINALLY SHIFTS FURTHER EAST INTO THE ATLANTIC OCEAN. THIS WILL
ENABLE THE RIDGE AXIS TO LIKEWISE SHIFT EAST TO THE U S EAST COAST
BY LATE DAY. CLOUD COVERAGE WILL INCREASE THROUGHOUT THE DAY AS
MOISTURE ADVECTS INTO THE REGION FROM THE SOUTHWEST. WEAK LIFT AND
FORCING WILL MOVE INTO THE OHIO VALLEY DURING THE COURSE OF THE
AFTERNOON WITH SCATTERED SHOWERS AND PERHAPS A THUNDERSTORM
SPREADING EAST INTO THE FORECAST AREA BY LATE AFTERNOON. MORE
EXPANSIVE COVERAGE TO RAINFALL WILL LIKELY HOLD OFF UNTIL THIS
EVENING AS MODEL SOUNDINGS INDICATING IT WILL TAKE MUCH OF THE DAY
TO MOISTEN THE BOUNDARY LAYER. WILL CARRY MAINLY LOW CHANCE POPS FOR
MID/LATE AFTERNOON.

TEMPS...FILTERED SUN THROUGH THE MORNING AND WARM ADVECTION AHEAD OF
THE FRONT WILL ENABLE ANOTHER WARM DAY PEAKING IN THE 70S. LOW LEVEL
THERMALS SUPPORTED MAX TEMPS AT OR JUST ABOVE MAVMOS IN THE
MID/UPPER 70S.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
ISSUED AT 304 AM EDT MON APR 21 2014

FORECAST CHALLENGES FOCUS ON PRECIP CHANCES TONIGHT AS THE FRONT
SWINGS THROUGH THE REGION...AND POTENTIAL FOR FROSTY TEMPS WEDNESDAY
MORNING.

WEAKENING UPPER WAVE WILL TRACK THROUGH THE OHIO VALLEY WITH THE
COLD FRONT TONIGHT WITH RAIN SHOWERS AND EMBEDDED THUNDERSTORMS.
MOST WIDESPREAD COVERAGE EXPECTED DURING THE EVENING AND EARLY
OVERNIGHT...WITH PRECIP GRADUALLY SHIFTING INTO THE SOUTHERN/EASTERN
PORTIONS OF THE FORECAST AREA AFTER 06Z TUESDAY. BRIEF PERIOD OF
ISENTROPIC LIFT AND SUBTLE LOW LEVEL CONVERGENCE WITHIN A NARROW
RIBBON OF DEEPER MOISTURE WILL BE THE MAIN RAINFALL CATALYSTS
TONIGHT AND WILL MAINTAIN LIKELY POPS. RAINFALL AMOUNTS WILL BE
GENERALLY LIGHT AT A QUARTER INCH OR LESS.

COLD FRONT WILL BE EAST OF THE FORECAST AREA BY DAYBREAK TUESDAY
WITH THE DEEPER MOISTURE DEPARTING ALONG WITH IT. EXPECT SKIES TO
CLEAR QUICKLY TUESDAY MORNING AS MODEL SOUNDINGS AND RH PROGS
INDICATING A RAPIDLY DRYING COLUMN. DESPITE STRONG COLD ADVECTION
AND A  SHARP WAVE ALOFT PASSING THROUGH THE LOWER GREAT LAKES DURING
THE COURSE OF THE DAY...EXPECT ANY CU FORMATION TO BE SIGNIFICANTLY
LIMITED BY THE INCREASING SUBSIDENCE AND DRY AIR ADVECTING INTO THE
REGION. EFFICIENT LOW LEVEL MIXING WILL BRING STRONGER WINDS TO THE
SURFACE TUESDAY AFTERNOON WITH MAX GUSTS UP TO 25 MPH.

HIGH PRESSURE RIDGE CENTERS ACROSS THE REGION TUESDAY NIGHT WITH
NORTHERLY WINDS BECOMING LIGHT AFTER MIDNIGHT. WITH CLEAR
SKIES...GOOD RADIATIONAL COOLING SETUP FOR THE REGION WITH POTENTIAL
FOR FROST ACCRUAL OVER MUCH OF THE FORECAST AREA AS TEMPS FALL INTO
THE 30S. WITH THE GROWING SEASON HAVING ADVANCED ENOUGH ACROSS THE
SOUTHERN HALF OF THE FORECAST AREA...POTENTIAL FOR FROST HEADLINES
EARLY WEDNESDAY. WILL CONTINUE TO HIGHLIGHT IN THE HWO AT THIS TIME.
REMAINDER OF THE SHORT TERM WILL BE DRY WITH WARM ADVECTION
COMMENCING BY LATE WEDNESDAY AS RIDGING ALOFT EXPANDS EAST INTO THE
OHIO VALLEY. A WARM FRONT WILL LIFT ACROSS THE FORECAST AREA
WEDNESDAY NIGHT AND MAY BRING A BRIEF INCREASE IN CLOUDS. ANY PRECIP
ASSOCIATED WITH THE WARM FRONT HOWEVER SHOULD REMAIN TO THE
NORTHWEST OF THE REGION.

TEMPS...MAVMOS GUIDANCE SUPPORTED LOW LEVEL THERMALS FOR HIGHS BOTH
TUESDAY AND WEDNESDAY...WITH TEMPS SLIPPING BACK INTO THE 60S BOTH
DAYS OVER MUCH OF THE FORECAST AREA. AS MENTIONED ABOVE...TUESDAY
NIGHT LOOKING FROSTY AS TEMPS EXPECTED TO FALL INTO THE 30S. WENT
NEAR MOS GUIDANCE FOR LOWS ALL THREE NIGHTS.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
ISSUED AT 231 AM EDT MON APR 21 2014

LONG TERM PERIOD WILL START WITH A FRONTAL SYSTEM APPROACHING THE
AREA. MODEL CONSISTENCY STILL LEAVES A BIT TO BE DESIRED...BUT MODEL
INSTABILITY PROGS...ALONG WITH CONVECTIVE PRECIP PROGS...DEEP LAYER
SHEAR AND TIMING OF FRONTAL PASSAGE...SUGGEST ORGANIZED CONVECTION
MAY BE A GOOD BET LATE THURSDAY AFTERNOON INTO THE OVERNIGHT. WILL
HAVE TO MONITOR THIS POTENTIAL AS THE WEEK WEARS ON.

WILL REMOVE ALLBLEND POPS FRIDAY AS FRONTAL BOUNDARY WILL BE WELL
EAST OF THE AREA AND HIGH PRESSURE BUILDING INTO THE AREA REGARDLESS
OF MODEL CHOICE. GUIDANCE BRINGS ANOTHER SYSTEM INTO THE AREA VERY
LATE IN THE PERIOD...BUT WILL TEMPER THESE POPS A BIT AS MODEL
INCONSISTENCIES ARE HIGH.

MAX TEMPERATURES NEEDED BUMPED UP A BIT MOST PERIODS AS 850 TEMPS
AND LOW LEVEL THICKNESSES SUGGESTED ALLBLEND TOO COOL.

&&

.AVIATION /DISCUSSION FOR THE 21/12Z TAFS/...
ISSUED AT 648 AM EDT MON APR 21 2014

VFR THROUGH THE FIRST 11-12 HOURS OF THE PERIOD.

EXPECTING INCREASING CLOUD COVER THROUGH THE DAY AS A COLD FRONT
APPROACHES. SHOWERS AND PERHAPS SOME THUNDERSTORMS WILL MOVE INTO
THE AREA LIKELY LATE THIS AFTERNOON AND THROUGH THE EVENING. WILL
CONTINUE WITH -SHRA AND VCTS MENTIONS...BUT BRING THE ARRIVAL TIME
UP A LITTLE EARLIER...TO AROUND THE 23-02Z TIME FRAME. EXPECT MVFR
CEILINGS AND PERHAPS BRIEF MVFR VISIBILITIES IN THE PRECIP...WHICH
MAY LINGER INTO THE OVERNIGHT AND THEN BECOME VFR LATE TONIGHT INTO
TOMORROW.

WINDS WILL START LIGHT AND VARIABLE...BECOMING SOUTHWESTERLY AROUND
12KT AND THEN NORTHWESTERLY LATE IN THE PERIOD.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN/CP
SHORT TERM...RYAN
LONG TERM...NIELD
AVIATION...NIELD

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