Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 271805
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
205 PM EDT WED APR 27 2016

.UPDATE...
THE LONG TERM SECTION HAS 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 942 AM EDT WED APR 27 2016

SURFACE ANALYSIS LATE THIS MORNING SHOWS A STATIONARY FRONT
ACROSS KENTUCKY. COOL NORTHEAST FLOW WAS IN PLACE ACROSS CENTRAL
INDIANA WITH TEMPS IN THE 50S. RADAR SHOWS A AREA OF RAIN SHOWERS
WITH ISOLATED THUNDERSTORMS STRETCHING ACROSS SOUTHERN ILLINOIS
INTO CENTRAL KENTUCKY.

WATER VAPOR IMAGERY SHOW AN UPPER SHORT WAVE ACROSS MISSOURI
POISED TO PIVOT INTO THE OHIO VALLEY LATER THIS AFTERNOON. AS THIS
OCCURS...THE FRONTAL SYSTEM TO THE SOUTH WILL ONCE AGAIN MOVE BACK
NORTHWARD INTO CENTRAL INDIANA AND BE A FOCUS FOR PRECIPITATION
DEVELOPMENT LATER THIS AFTERNOON AND EVENING. GIVEN RECENT RADAR
TRENDS...HAVE LOWER POPS FOR THE NEXT 1-2 HOURS...FOCUSING BEST
POPS DURING THE LATE AFTERNOON HOURS. ALSO GIVEN THE CLOUD COVER
AND THE COOL NORTHEAST FLOW ACROSS THE FORECAST AREA...TRENDED
HIGHS COOLER THAN THE PREVIOUS FORECAST...CLOSER TO THE ONGOING
LAV 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 NIGHT THROUGH WEDNESDAY/...
ISSUED AT 205 PM EDT WED APR 27 2016

LATE WEEKEND SYSTEM WILL BE THE MAIN FOCUS FOR THE LONG TERM.

MODELS ARE HAVING ISSUES REGARDING MODEL TO MODEL AND RUN TO RUN
CONSISTENCY WITH A WEEKEND SYSTEM. THE 12Z GFS IS FASTER THAN THE
00Z ECMWF WITH KICKING A CENTRAL PLAINS SYSTEM EAST ACROSS THE OHIO
VALLEY. WITH RUN TO RUN AND MODEL TO MODEL ISSUES...PREFER TO NO
MAKE ANY SIGNIFICANT CHANGES TO THE REGIONAL BLEND THAT HAS THE BEST
CHANCE OF CONVECTION SATURDAY NIGHT AND SUNDAY WITH LINGERING LOW
CHANCES INTO MONDAY. AFTER THAT...HIGH PRESSURE SHOULD PROVIDE DRY
WEATHER THROUGH TUESDAY NIGHT. MEANWHILE...MORE SHOWER AND
THUNDERSTORM CHANCES LOOK WARRANTED WEDNESDAY AS AN UPPER TROUGH
DROPS DOWN IN NORTHWEST FLOW ALOFT.

CLOUD COVER AND LOW LEVEL THERMAL PROGS SUGGEST REGIONAL BLEND
SEASONABLE TEMPERATURES LOOK OK THROUGH THE LONG TERM WITH HIGHS
MOSTLY IN THE 60S NORTH AND LOWER 70S SOUTH.

&&

.AVIATION /DISCUSSION FOR THE 271800Z TAF ISSUANCE/...
ISSUED AT 1250 PM EDT WED APR 27 2016

SHOULD SEE MOSTLY MVFR CONDITIONS THROUGH THE AFTERNOON AND EARLY
OVERNIGHT PER GFS LAMP. HOWEVER...IFR CONDITIONS HAVE BEEN LINGERING
INTO THE LATE MORNING. SO...MAY HAVE INCLUDE A TEMPO IFR GROUP FOR
THE FIRST COUPLE OF HOURS. WILL TAKE A LAST MINUTE LOOK WITH REGARD
TO THAT. AFTER THAT...GFS LAMP SUGGESTS CONDITIONS WILL ONCE AGAIN
DETERIORATE TO IFR AT LEAST AT TIMES. CONFIDENCE IS NOT GREAT ON
PRECISE TIMING BUT GOOD ON TRENDS. SHOWERS WILL INCREASE IN COVERAGE
THIS AFTERNOON AND EARLY EVENING. THERE WILL BE PLENTY OF ELEVATED
INSTABILITY AVAILABLE FOR THUNDER TO BE A THREAT. LIGHTNING TRENDS
BACK THIS UP.

EXPECT A FRONT...JUST SOUTH OF THE TERMINALS...TO LIFT NORTHEAST
ACROSS THE TAF SITES OVERNIGHT AS AN UPPER LOW MOVES INTO IOWA.
ASSOCIATED COLD FRONT SHOULD THEN SWEEP EAST ACROSS CENTRAL INDIANA
TOMORROW AFTERNOON. WINDS WILL SHIFT FROM EAST AND NORTHEAST TO
SOUTHEAST AND SOUTH TONIGHT AND FINALLY SOUTHWEST AND WEST TOMORROW
AFTERNOON.

&&

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

$$

SYNOPSIS...RYAN
NEAR TERM...TDUD
SHORT TERM...RYAN
LONG TERM...MK
AVIATION...MK



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