Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 270747
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
347 AM EDT WED APR 27 2016

.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 347 AM EDT WED APR 27 2016

SHOWERS AND EMBEDDED THUNDERSTORMS WILL ONCE AGAIN INCREASE ACROSS
THE REGION LATER TODAY AND TONIGHT AS A FRONTAL BOUNDARY REMAINS
ACROSS CENTRAL INDIANA. ADDITIONAL STORMS ARE POSSIBLE THURSDAY AS
LOW PRESSURE TRACKS INTO THE AREA. DRY WEATHER IS EXPECTED FRIDAY
BEFORE RAIN AND STORMS RETURN FOR THE WEEKEND AS ANOTHER LOW
PRESSURE SYSTEM TRACKS THROUGH THE OHIO VALLEY.

&&

.NEAR TERM /TODAY/...
ISSUED AT 347 AM EDT WED APR 27 2016

MUCH MORE STABLE AIRMASS LEFT ACROSS MUCH OF THE FORECAST AREA IN
THE WAKE OF THE TUESDAY AFTERNOON AND EVENING CONVECTION. THE
FRONTAL BOUNDARY HAS DROPPED ALL THE WAY INTO FAR SOUTHERN INDIANA
WITH THE ENTIRE FORECAST AREA CARRYING SOME EASTERLY COMPONENT TO
SURFACE WINDS. DRIER AIRMASS STEADILY ADVECTING INTO THE REGION FROM
THE NORTHEAST WITH DEWPOINTS INTO THE 40S OVER NORTHERN COUNTIES.
07Z TEMPS RANGED FROM NEAR 50 IN FAR NORTHERN COUNTIES TO THE LOWER
60S OVER THE FAR SOUTH.

COMPLEX FORECAST FOR TODAY AS MODELS REALLY STRUGGLING WITH THE
DETAILS WITH RESPECT TO ONGOING CONVECTIVE LINE EVOLUTION OVER THE
MISSOURI VALLEY AND OZARKS AND TIMING AND IMPACTS FOR CENTRAL
INDIANA AS THE FRONTAL BOUNDARY BEGINS A NORTHWARD TREK.

EXPECT FRONTAL BOUNDARY LOCATION TO REMAIN LARGELY STEADY STATE
THROUGH THE MORNING EXTENDING FROM CENTRAL KENTUCKY WEST ACROSS
SOUTHWEST INDIANA AND SOUTHERN ILLINOIS. OCCLUSION OF THE DEEP
SURFACE LOW OVER EASTERN NEBRASKA TODAY WILL PROMPT THE BOUNDARY TO
RETURN NORTH AS A WARM FRONT THIS AFTERNOON...LIKELY LIFTING
SOMEWHERE UP INTO THE SOUTHERN FORECAST AREA BY LATE DAY.

WITH A STABLE AIRMASS OVER THE REGION...SHOULD SEE MAINLY DRY
CONDITIONS THROUGH DAYBREAK WITH ONLY A SMALL CHANCE FOR SHOWERS
DEVELOPING OVER THE SOUTHWEST HALF OF THE FORECAST AREA BY MIDDAY.
EVOLUTION OF THE CONVECTIVE LINE OUT WEST IS KEY FOR EXPECTATIONS
THIS AFTERNOON. CURRENT THINKING IS THAT THE LINE WILL SLOWLY
WEAKENS AS IT MOVES EAST INTO THE MID MISSISSIPPI VALLEY AFTER
DAYBREAK AND ENCOUNTERS A MORE STABLE AIRMASS. LINE REMNANTS WILL
PROGRESS EAST INTO THE REGION AS THE AFTERNOON PROGRESSES WITH
PRECIP CHANCES STEADILY INCREASING BY LATE DAY AS MOISTURE POOLS
ALONG THE WARM FRONT...ESPECIALLY TO THE SOUTHWEST OF INDIANAPOLIS.
WILL BRING IN A SCATTERED THUNDER MENTION FOR THE WABASH VALLEY BY
LATE AFTERNOON...OTHERWISE KEEPING THUNDER ISOLATED ELSEWHERE WITH
LIMITED LEVELS OF ELEVATED INSTABILITY PRESENT.

TEMPS...LOW CLOUDS AND PATCHY FOG ENCOMPASSING MUCH OF THE REGION
THIS MORNING...TRAPPED BENEATH A SHALLOW BUT SHARP INVERSION. MODEL
SOUNDINGS SHOW THIS INVERSION REMAINING STRONG INTO THE AFTERNOON
BEFORE SLOWLY WEAKENING AS THE FRONT LIFTS BACK INTO THE FORECAST
AREA. WITH THE CLOUDS AND DRIER EASTERLY FLOW FOR MUCH OF THE
DAY...EXPECT HIGHS REMAIN IN THE LOWER AND MID 60S OVER MUCH OF THE
AREA. ONLY EXCEPTION IS OVER SOUTHERN COUNTIES WHERE PASSAGE OF THE
BOUNDARY LATE THIS AFTERNOON MAY ENABLE HIGHS TO RISE INTO THE LOWER
70S. THIS GENERALLY PLACES HIGHS BETWEEN THE WARMER MAV AND THE
VERY COOL MET GUIDANCE.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 347 AM EDT WED APR 27 2016

FORECAST CHALLENGES PRIMARILY FOCUS ON PRECIP CHANCES TONIGHT
THROUGH THURSDAY NIGHT WITH THE FRONTAL BOUNDARY CONTINUING TO
MEANDER ACROSS THE REGION.

SURFACE LOW PRESSURE WILL STEADILY WEAKEN OVER THE MISSOURI VALLEY
TONIGHT WITH A WEAKENING OCCLUDED FRONT PRESSING EAST TO A LOCATION
NEAR THE WABASH RIVE BY DAYBREAK THURSDAY. INSTABILITY AXIS WILL
PERSIST IN THE WARM SECTOR BETWEEN THE WARM FRONT DRAPED ACROSS THE
REGION AND THE APPROACHING OCCLUDED BOUNDARY...WITH RENEWED
CONVECTIVE DEVELOPMENT EXPECTED OVER THE MID MISSISSIPPI VALLEY THIS
EVENING. CONVECTION WILL EXPAND NORTHEAST INTO THE FORECAST AREA
THIS EVENING INTO THE OVERNIGHT...AIDED BY DIFFLUENCE ALOFT AND AN
INCREASE IN MOIST LOW LEVEL FLOW AHEAD OF THE BOUNDARY. THE RESULT
WILL BE THE BEST POTENTIAL FOR WIDESPREAD SHOWERS AND EMBEDDED
THUNDER. WILL CONTINUE WITH CATEGORICAL POPS FOR THE ENTIRE FORECAST
AREA TONIGHT. STORMS SHOULD REMAIN SUBSEVERE THIS EVENING WITH ONLY
POSSIBLE EXCEPTION ACROSS THE LOWER WABASH VALLEY WHERE POTENTIAL
FOR CONVECTION TO BECOME SURFACE BASED AS THE WARM FRONT LIFTS
NORTH. HIGH PRECIP WATER VALUES SUPPORTS RAINFALL AMOUNTS IN EXCESS
OF AN INCH BY THURSDAY MORNING...ESPECIALLY SOUTH OF I-70. COULD SEE
LOCALIZED FLOODING AS MANY OF THESE AREAS RECEIVED AN INCH OR BETTER
ON TUESDAY AFTERNOON AND EVENING.

THE WEAKENED SURFACE WAVE WILL KICK OUT TO THE EAST WITH THE UPPER
ENERGY...TRACKING ACROSS THE LOWER GREAT LAKES THURSDAY NIGHT BEFORE
DEPARTING TO THE EAST. SOUTHERLY FLOW AND MODEST INSTABILITY
DEVELOPING ON THURSDAY WITH THE BOUNDARY LINGERING OVER THE AREA
SUPPORTIVE OF SCATTERED CONVECTION ORGANIZING...ESPECIALLY DURING
PEAK HEATING IN THE AFTERNOON. BRIEF PERIOD OF DECENT BL SHEAR
DURING THE AFTERNOON MAY BE ENOUGH TO SUPPORT A LOW SEVERE WEATHER
RISK OVER EASTERN PORTIONS OF THE FORECAST AREA WITHIN THE UNSTABLE
AIRMASS. WBZERO VALUES BETWEEN 7-8KFT SUGGEST LARGE HAIL WOULD BE A
PRIMARY CONCERN ALONG WITH STRONGER WIND GUSTS AS CORES COLLAPSE.
LACK OF DEEPER MOISTURE MUDDLES THE POTENTIAL SOMEWHAT...BUT THIS
WILL BE SOMETHING TO MONITOR GOING FORWARD.

SHOWERS WILL END THURSDAY NIGHT AS THE LOW DEPARTS OFF TO THE EAST.
ARRIVAL OF WEAK SURFACE HIGH PRESSURE AND A RIDGE ALOFT WILL PROVIDE
DRY PLEASANT WEATHER FOR FRIDAY. MODEL SOUNDINGS ONCE AGAIN SHOW A
LINGERING SHALLOW LAYER OF MOISTURE BENEATH AN INVERSION WHICH
SUGGESTS THE POSSIBILITY OF A STUBBORN LOWER CLOUD DECK TAKING TIME
TO MIX OUT ON FRIDAY. MOISTURE WILL QUICKLY EXPAND INTO THE LOWER
OHIO VALLEY LATE FRIDAY NIGHT AS LOW PRESSURE KICKS OUT INTO THE
SOUTHERN PLAINS. WILL CONTINUE WITH INTRODUCING A LOW CHANCE FOR
SHOWERS IN THE WABASH VALLEY IN THE PREDAWN HOURS SATURDAY BUT WITH
BETTER ISENTROPIC LIFT REMAINING TO THE WEST...EXPECT MOST OF THE
AREA WILL REMAIN DRY THROUGH 12Z SATURDAY.

TEMPS...LOW LEVEL THERMALS SUPPORTED A MOS BLEND FOR HIGHS ON
THURSDAY AS MOST OF THE AREA SHOULD RISE INTO THE 70S. PREFER THE
COOLER MAVMOS GUIDANCE FOR FRIDAY WITH UNCERTAINTY ON LOW CLOUD
DEPARTURE AS DISCUSSED ABOVE. MAVMOS GUIDANCE LOOKED REASONABLE FOR
OVERNIGHT LOWS THROUGH THE PERIOD.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 230 AM EDT WED APR 27 2016

MODELS ARE SIMILAR...BUT RUN TO RUN CONSISTENCY HAS NOT BEEN THAT
GREAT. THAT LEADS TO A LOWER CONFIDENCE FORECAST...SO JUST ACCEPTED
THE SUPERBLEND INITIALIZATION FOR MOST ITEMS.

AN UPPER LOW WILL MOVE ACROSS THE REGION DURING THE LONG TERM.
LATEST OPERATIONAL RUNS HAVE SPED THINGS UP...BUT ENSEMBLE QPF PLOTS
SHOW MANY MEMBERS HOLDING ONTO RAIN LONGER THAN THE OPERATIONAL
RUNS. THUS WITH THE UNCERTAINTY...AND TO AVOID FLIP-FLOPPING...LEFT
POPS IN THROUGHOUT THE LONG TERM.

TEMPERATURES SHOULD REMAIN NEAR NORMAL THROUGH THE PERIOD.

&&

.AVIATION /DISCUSSION FOR THE 270600Z TAFS/...
ISSUED AT 1230 AM EDT WED APR 27 2016

MVFR CEILINGS 015-020 OVER NORTHEAST INDIANA EXPECTED TO ADVECT OVER THE
TERMINALS OVER THE NEXT SEVERAL HOURS IN THE POST FRONTAL ZONE. SHORT TERM
MODEL GUIDANCE SUGGESTS THESE CEILINGS WILL LINGER INTO THE MIDDAY HOURS
OF WEDNESDAY.

SURFACE WINDS 060-080 DEGREES AT 8-13 KTS EXPECTED THROUGH MIDDAY WEDNESDAY.

&&

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

&&

$$

SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM...50
AVIATION...JAS



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