284
FXUS63 KIND 180042
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
842 PM EDT FRI AUG 17 2018
UPDATE
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
SYNOPSIS
ISSUED AT 225 PM EDT FRI AUG 17 2018
RAIN CHANCES WILL CONTINUE TONIGHT AS LOW PRESSURE MOVES ACROSS
AND EXITS THE AREA. A FEW LINGERING SHOWERS WILL BE POSSIBLE EARLY
ON SATURDAY AS THE LOW DEPARTS. HIGH PRESSURE IS EXPECTED TO
BUILD ACROSS CENTRAL INDIANA ON SATURDAY AFTERNOON AND SATURDAY
NIGHT. THIS WILL BRING DRY WEATHER FOR THE LATTER PARTS OF THE
WEEKEND.
ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO ARRIVE IN THE AREA ON
MONDAY AND TUESDAY. THIS WILL BRING MORE RAIN CHANCES TO CENTRAL
INDIANA EARLY NEXT WEEK. THAT LOW WILL DEPART BY MID
WEEK...BRINGING A RETURN TO DRY WEATHER FOR THE END OF THE NEXT
WORK WEEK.
LOOK FOR TEMPERATURES TO REMAIN AT OR BELOW SEASONAL NORMALS OVER
THE NEXT WEEK.
NEAR TERM /TONIGHT/
ISSUED AT 837 PM EDT FRI AUG 17 2018
SCATTERED CONVECTION CONTINUES ACROSS THE AREA, AS A MID LEVEL
VORTICITY LOBE AND DIFFUSE SURFACE COLD FRONT DRIFT SOUTH THROUGH
THE AREA.
EXPECTING A GRADUAL DECREASE IN COVERAGE OF SHOWER ACTIVITY FROM
THIS POINT ON AS HEATING IS LOST. HOWEVER, THE PRESENCE OF THE MID
AND LEVEL AND SURFACE FEATURES SUGGESTS THE POTENTIAL FOR SOME
SHOWERS AND THUNDERSTORMS WILL LINGER INTO THE EARLY MORNING HOURS
OF SATURDAY.
PREVIOUS DISCUSSION FOLLOWS.
SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS LOW PRESSURE OVER
LOWER MICHIGAN AND NORTHERN INDIANA. BROAD CYCLONIC FLOW WAS IN
PLACE ACROSS THE REGION GOES16 SHOWS A SWIRLING CLOUDS ACROSS THE
REGION...DENOTING THE CIRCULATION. POP UP CUMULUS CLOUDS WERE
FOUND FILLING IN ANY CLEAR GAPS AS CONVECTIVE TEMPERATURES WERE
REACHED. SURFACE FLOW WAS GENERALLY SOUTHERLY OR SOUTHWESTERLY AND
DEW POINTS REMAINED IN THE VERY MOIST UPPER 60S AND LOWER 70S.
RADAR SHOWS SHOWER DEVELOPMENT OVER WESTERN CENTRAL INDIANA AS
CONVECTIVE TEMPERATURES WERE BEING REACHED.
MODELS THIS AFTERNOON SUGGEST A WEAK SHORT WAVE EMBEDDED WITHIN
THE TROUGHY FLOW ALOFT PASSING ACROSS CENTRAL INDIANA. THIS
COMBINED WITH SOME AFTERNOON HEATING SHOULD LEAD TO SOME SCATTERED
SHOWERS LASTING INTO THE EVENING HOURS. TIME HEIGHT SECTIONS
CONTINUE TO SHOWS GOOD LIFT THROUGH THE LATE AFTERNOON AND PAST
00Z WITH GOOD LOWER LEVEL MOISTURE AVAILABLE. FORECAST SOUNDINGS
AGAIN SHOW FAVORABLE LAPSE RATES FOR AFTERNOON CONVECTION. HRRR
ALSO SUGGESTS SHOWER AND STORM DEVELOPMENT THIS
AFTERNOON...CONTINUING INTO THE EVENING. THUS WILL TREND POPS AT
OR ABOVE THE FORECAST BUILDER BLENDS WITH THIS FAVORABLE SET-UP
FOR RAIN.
TROUGH AXIS IS EXPECTED TO PIVOT SOUTHEAST ACROSS THE FORECAST
AREA OVERNIGHT...AND RAIN CHANCES SHOULD DIMINISH AS THIS AXIS
PASSES ALONG WITH THE LOSS IF DAYTIME HEATING. THUS FOR NOW...WILL
FOCUS BEST POPS IN THE 20Z-04Z TIME FRAME...TRENDING DOWNWARD
AFTER THAT. GIVEN THE EXPECTED CLOUDS AND RAIN...WILL TREND LOWS
AT OR ABOVE THE FORECAST BUILDER BLENDS.
SHORT TERM /SATURDAY THROUGH MONDAY/
ISSUED AT 225 PM EDT FRI AUG 17 2018
MODELS SHOW THE TROUGH AXIS SAGGING SOUTHEAST OF CENTRAL INDIANA
ON SATURDAY MORNING AS NW FLOW DEVELOPS ALOFT. FORECAST SOUNDINGS
RESPOND WITH A DRY COLUMN AS THE GFS SHOWS A GOOD MID LEVEL
INVERSION ARRIVING BY 12Z. TIME HEIGHTS SHOW SUBSIDENCE ARRIVING
BY 15Z. THUS FORECAST BUILDER WILLING...WILL TRY AND TREND TOWARD
A DRY FORECAST FOR SATURDAY WITH DECREASING CLOUDS IN THE WAKE OF
THE FRONT. WITH MINIMAL TEMPERATURE ADVECTION IN PLACE...WILL
TREND HIGHS CLOSE TO THE FORECAST BUILDER BLENDS.
ON SATURDAY NIGHT THROUGH SUNDAY NIGHT THE MODELS CLEARLY SHOW
STRONG HIGH PRESSURE IN PLACE ACROSS THE REGION...STRETCHING FROM
ONTARIO...ACROSS THE GREAT LAKES TO THE OHIO VALLEY. FORECAST
SOUNDINGS AGAIN SHOW A DRY COLUMN AND SUBSIDENCE IS DEPICTED
WITHIN THE MIDDLE LEVELS. THUS WILL TREND TOWARD A DRY FORECAST
HERE AND STICK CLOSE TO THE FORECAST BUILDER TEMPERATURES FOR
HIGHS AND LOWS.
ON MONDAY THE GFS SUGGESTS LOW PRESSURE PUSHING TOWARD INDIANA
FROM THE CENTRAL MISSISSIPPI RIVER VALLEY. MODELS SUGGEST BY MID
TO LATE IN THE DAY ON MONDAY...A WARM FRONT WILL ARRIVE IN
CENTRAL INDIANA AHEAD OF THE DEEPENING LOW OVER ILLINOIS.
ALOFT...THE GFS SHOW A FAVORABLE UPPER LEVEL TROUGH WITH AMPLE
FORCING. THUS WILL TREND TOWARD HIGH POPS LATE IN THE DAY AS THESE
FEATURE ARRIVE.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
ISSUED AT 330 PM EDT FRI AUG 17 2018
PRIMARY FOCUS OF THE LONG TERM WILL BE EARLY IN THE PERIOD AS A LOW
PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES. THIS WILL NECESSITATE
PRECIPITATION CHANCES IN THE FIRST 48 HOURS OR SO BEFORE A LARGE AND
SOMEWHAT FALL-LIKE HIGH PRESSURE SYSTEM PUSHES INTO THE REGION,
BRINGING DRY AND SOMEWHAT COOLER WEATHER RIGHT ON TIME MID TO LATE
WEEK AS METEOROLOGICAL SUMMER NEARS ITS CLOSE.
BLENDED INITIALIZATION WAS GENERALLY ACCEPTABLE MINUS REMOVING SOME
SPOTTY SLIGHT CHANCES LATE IN THE WEEK.
AVIATION /DISCUSSION FOR THE 180000Z TAFS/
ISSUED AT 632 PM EDT FRI AUG 17 2018
SCATTERED CONVECTION IS EXPECTED TO LINGER IN THE VICINITY OF THE
TERMINALS THROUGH ABOUT SUNSET, AS A MID LEVEL VORTICITY LOBE AND
SURFACE COLD FRONT, MOVE THROUGH.
OTHERWISE, LIGHT WINDS AND A HUMID AIR MASS MAY LEAD TO THE
DEVELOPMENT OF IFR CEILINGS, ALONG WITH SOME FOG, AFTER 180600Z.
NOT SURE HOW WIDESPREAD THESE CONDITIONS WILL GET AT THIS TIME, AS
SOME LINGERING MID LEVEL CLOUD MAY WORK AGAINST THE LOW CEILINGS
FORMING.
SURFACE WINDS 240-290 DEGREES AT 5-8 KTS EARLY THIS EVENING WILL
BECOME LIGHT AFTER SUNSET.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...PUMA
NEAR TERM...PUMA/JAS
SHORT TERM...PUMA
LONG TERM...NIELD
AVIATION...JAS
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