029
FXUS63 KIND 191036
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
636 AM EDT SUN MAY 19 2019
UPDATE
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
SYNOPSIS
ISSUED AT 354 AM EDT SUN MAY 19 2019
SHOWERS AND THUNDERSTORMS WILL IMPACT CENTRAL INDIANA THROUGH THIS
EVENING WITH THE POSSIBILITY OF SEVERE WEATHER THIS AFTERNOON AND
EVENING AHEAD OF A COLD FRONT. THE FRONT WILL SWING THROUGH THE
REGION LATE THIS EVENING WITH COOLER AND DRIER CONDITIONS TO START
THE NEW WEEK AS HIGH PRESSURE TRACKS THROUGH THE GREAT LAKES. MUCH
WARMER WEATHER RETURNS BY MIDWEEK AND WILL CONTINUE INTO THE HOLIDAY
WEEKEND ALONG WITH PERIODIC THREATS FOR SHOWERS AND THUNDERSTORMS AS
A FRONTAL BOUNDARY MEANDERS ACROSS THE OHIO VALLEY.
NEAR TERM /TODAY THROUGH THIS EVENING/
ISSUED AT 354 AM EDT SUN MAY 19 2019
CLOUDS WERE INCREASING OVER CENTRAL INDIANA EARLY THIS MORNING WITH
AREAS OF SHOWERS LIFTING NORTHEAST INTO THE WABASH VALLEY. WINDS
WERE BECOMING GUSTY OVER ILLINOIS AS WELL WITH AN EXPANDING LOW
LEVEL JET APPROACHING FROM THE WEST. 07Z TEMPERATURES RANGED FROM
THE UPPER 60S TO THE MID 70S.
THE APPROACH OF A COLD FRONT LATER TODAY WILL BRING THE THREAT FOR
RAIN AND THUNDERSTORMS ACROSS THE FORECAST AREA THROUGHOUT THE DAY
WITH AN INCREASING THREAT FOR SEVERE WEATHER FOCUSED THIS AFTERNOON
INTO THE EARLY EVENING. IN ADDITION...WINDY CONDITIONS ARE EXPECTED
ALL DAY WITH NON-THUNDERSTORM WIND GUSTS PEAKING AROUND OR JUST
ABOVE 40 MPH IN SPOTS.
THE AFOREMENTIONED LOW LEVEL JET WILL ADVECT DEEPER MOISTURE INTO
THE REGION OVER THE NEXT SEVERAL HOURS...WITH SHOWERS AND PERHAPS A
FEW THUNDERSTORMS INCREASING IN COVERAGE AS THE MORNING PROGRESSES.
WHILE VARIATIONS IN CONVECTIVE EVOLUTION EXISTS THROUGHOUT THE CAMS
AND OTHER MODEL GUIDANCE...FEEL AN INCREASINGLY LIKELY SCENARIO IS
TWO PRIMARY PERIODS OF CONVECTION IMPACTING CENTRAL INDIANA. THE
FIRST WILL BE LATER THIS MORNING INTO THE EARLY AFTERNOON AS THE
PLUME OF DEEPEST MOISTURE MOVES ACROSS THE AREA. PRECIP WATER VALUES
ARE LIKELY TO PEAK AT 1.50 TO 1.75 INCHES WITH THE LOW LEVEL JET
PROVIDING AMPLE LIFT TO MAINTAIN REGENERATE CONVECTION INTO THE
EARLY AFTERNOON. THE PRESENCE OF INCREASING LEVELS OF BL SHEAR AND
HELICITY DO SUPPORT STRONGER STORMS FROM THIS FIRST BATCH OF
CONVECTION...ESPECIALLY BY MIDDAY AS HEATING INCREASE. THAT BEING
SAID...LAPSE RATES AND INSTABILITY LEVELS ARE NOT OVERLY IMPRESSIVE
THROUGH 18Z AND WHILE ANY ELEVATED CORE MAY TAP INTO THE LOW LEVEL
JET AND PULL STRONGER WINDS TO THE SURFACE...EXPECT MUCH OF THE
STORMS THROUGH EARLY AFTERNOON REMAIN SUBSEVERE WITH PERHAPS AN
UPTICK IN INTENSITY AS THE LINE MOVES INTO A MORE FAVORABLE
ENVIRONMENT OVER EASTERN COUNTIES IN THE 18-21Z PERIOD BEFORE MOVING
OFF TO THE EAST.
ONCE THE FIRST BATCH OF CONVECTION SHIFTS EAST WITH THE DEEPER
MOISTURE PLUME AND LOW LEVEL JET CORE HOWEVER...NUMEROUS SIGNS POINT
TO A MORE CONDUCIVE ATMOSPHERE FOR SEVERE CONVECTION WITHIN A WINDOW
ENCOMPASSING LATE AFTERNOON INTO THE EARLY EVENING ALONG AND
IMMEDIATELY AHEAD OF THE COLD FRONT. BOUNDARY LAYER FLOW WHILE NOT
AS STRONG AS EARLIER IN THE DAY REMAINS SUPPORTIVE FOR RENEWED
CONVECTIVE DEVELOPMENT. DIFFLUENCE ALOFT WILL ENHANCE WITH THE
ARRIVAL OF THE NEGATIVELY TILTED UPPER TROUGH AND A WEAK UPPER
JETLET WILL BE IN AN IDEAL LOCATION TO ENHANCE CONVECTIVE
REDEVELOPMENT. OF NOTED INTEREST IS THE HINT OF A SMALL WAVE
DEVELOPING ALONG THE FRONT BY EARLY EVENING WHICH COULD CONCEIVABLY
PRODUCE A SHORT PERIOD WITH BACKED BOUNDARY LAYER FLOW AND
CONSEQUENTLY AN AXIS OF STRONGER BL SHEAR AND HELICITY IMMEDIATELY
AHEAD OF THE FRONT. THE LACK OF DEEPER MOISTURE BY LATE AFTERNOON
MAY BE A MITIGATING FACTOR AT LEAST FROM A COVERAGE STANDPOINT BUT
CAPES LEVELS TO 1000 J/KG OR GREATER WOULD LIKELY BE ENOUGH
INSTABILITY TO GENERATE A BROKEN LINE OF CONVECTION AHEAD OF THE
FRONT...SOMETHING BEING SUGGESTED BY SEVERAL OF THE CAMS.
WHILE THE SETUP IS NOT NEARLY AS CLEAN AS DESIRED...THE PRIMARY
SEVERE WEATHER THREAT WILL LIKELY RESIDE WITHIN THIS 4-6 HOUR
WINDOW FROM MID AFTERNOON INTO THE EARLY EVENING AS THE INITIAL
BATCH OF CONVECTION SHIFTS EAST FOLLOWED BY THE BROKEN LINE OF
CONVECTION AHEAD OF THE FRONTAL BOUNDARY. WHILE DAMAGING WIND
GUSTS REMAIN THE PRIMARY THREAT CONSIDERING THE STRONGER FLOW IN
THE UPPER LEVELS OF THE BOUNDARY LAYER...LARGE HAIL AND A FEW
TORNADOES REMAIN A POSSIBILITY CONSIDERING THE INCREASE IN
DIRECTIONAL SHEAR SETTING UP JUST AHEAD OF THE COLD FRONT.
TEMPS...CLOUDS AND CONVECTION THROUGH THE MORNING WILL SLOW TEMP
RISES BUT POTENTIAL FOR SOME SUN PRIOR TO THE CONVECTION WITH THE
COLD FRONT LATER TODAY SHOULD ENABLE MUCH OF THE AREA TO WARM INTO
THE MID AND UPPER 70S. UTILIZED A MODEL BLEND WHICH WAS SUPPORTED BY
LOW LEVEL THERMALS.
SHORT TERM /OVERNIGHT TONIGHT THROUGH TUESDAY NIGHT/
ISSUED AT 354 AM EDT SUN MAY 19 2019
FORECAST CHALLENGES FOCUS ON TEMPERATURES THROUGH THE SHORT TERM AND
RETURNING PRECIP CHANCES BY TUESDAY NIGHT.
ANY LINGERING CONVECTION WILL DEPART THE EASTERN COUNTIES AROUND OR
SHORTLY AFTER 06Z TONIGHT AS THE COLD FRONT SWEEPS EAST OF THE
REGION. DESPITE A COOLER...DRIER AIRMASS EXPANDING INTO THE FORECAST
AREA OVERNIGHT...MODEL SOUNDINGS SHOW A SHALLOW BUT STOUT INVERSION
DEVELOPING AND PERSISTING THE REST OF THE NIGHT AND POTENTIALLY
THROUGH MOST OF MONDAY MORNING. WILL KEEP CLOUD COVERAGE UP A BIT
THROUGH DAYBREAK MONDAY WITH SKIES BECOMING PARTLY CLOUDY DURING THE
DAY AS PROGRESSIVELY DRIER AIR SUBSIDES INTO THE BOUNDARY LAYER.
WITH COLD ADVECTION IN THE WAKE OF THE FRONT FOR MONDAY...LIKELY TO
BE SOME REDEVELOPMENT OF DIURNAL CU AS WELL...ESPECIALLY FOCUSED
ACROSS THE NORTHERN HALF OF THE FORECAST AREA.
HIGH PRESSURE WILL EXPAND ACROSS THE REGION MONDAY INTO TUESDAY WITH
DRY AND COOLER WEATHER AS WINDS CARRY A NORTHERLY COMPONENT THROUGH
MONDAY NIGHT. AN INCREASINGLY AMPLIFIED FLOW REGIME WILL DEVELOP
ALOFT THROUGH THE SHORT TERM AS AN IMPRESSIVE UPPER LOW KICKS OUT OF
THE SOUTHERN ROCKIES MONDAY NIGHT THEN ROTATES INTO THE HIGH PLAINS
BY TUESDAY NIGHT. A RAPIDLY DEEPENING SURFACE WAVE WILL ACCOMPANY
THE UPPER LOW FROM THE TEXAS PANHANDLE NORTH INTO WESTERN NEBRASKA
RESULTING IN A MULTI-DAY WIDESPREAD SEVERE WEATHER THREAT ACROSS THE
SOUTHERN AND CENTRAL PLAINS EXPANDING EAST INTO THE OZARKS AND
MISSOURI VALLEY. DOWNSTREAM RIDGING WILL ONCE AGAIN STRENGTHEN
ACROSS THE MISSISSIPPI AND OHIO VALLEYS BY TUESDAY BEFORE SHIFTING
EAST BY EARLY WEDNESDAY.
ANY LINGERING CU FROM MONDAY AFTERNOON WILL DIMINISH MONDAY EVENING
WITH MAINLY CLEAR SKIES DEVELOPING. CLEARING WILL BE SHORT LIVED AS
MID AND HIGH LEVEL CLOUDS ASSOCIATED WITH CONVECTION ACROSS THE
PLAINS SPREADS EAST INTO THE REGION EARLY TUESDAY BEFORE LIFTING
NORTH LATER IN THE DAY. A DRY EASTERLY FLOW WILL PERSIST IN THE
BOUNDARY LAYER FOR MUCH OF TUESDAY BEFORE VEERING TUESDAY NIGHT.
DEEPER MOISTURE AND LIFT WILL EXPAND INTO THE OHIO VALLEY AHEAD OF
AN OCCLUDED BOUNDARY WITH NUMEROUS SHOWERS AND THUNDERSTORMS
ARRIVING LATE TUESDAY NIGHT.
TEMPS...EXPECT COOLER TEMPERATURES THROUGH MUCH OF THE SHORT TERM
BEFORE WARMTH RETURNS MIDWEEK. TRENDED TOWARDS THE COOLER MET
GUIDANCE FOR HIGHS MONDAY WITH COLD ADVECTION ACROSS THE AREA. AN
OVERALL MODEL BLEND SHOULD WORK FINE FOR TUESDAY AS TEMPERATURES
RECOVER INTO THE UPPER 60S AND LOWER 70S. COOLER NIGHTS ARE EXPECTED
THROUGH THE SHORT TERM AS WELL...WITH THE LOWEST TEMPS MONDAY NIGHT
INTO THE 40S WITH A FEW SPOTS POTENTIALLY SLIPPING INTO THE LOWER
40S.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
ISSUED AT 240 AM EDT SUN MAY 19 2019
ENSEMBLES INDICATE MEAN UPPER RIDGING IS EXPECTED OVER THE OHIO
VALLEY DURING MOST OF THIS PERIOD. A SHORT WAVE TROUGH MAY PASS
THROUGH THE GREAT LAKES TOWARDS NEXT WEEKEND, WHICH MAY SUPPRESS
THE RIDGE SOMEWHAT BY THEN.
ENSEMBLES ARE IN BETTER AGREEMENT IN PUSHING A WEAKENING FRONTAL
SYSTEM THROUGH THE AREA ON WEDNESDAY. WILL KEEP POPS IN THE
FORECAST FOR WEDNESDAY TO COVER THIS FRONT.
THERE MAY BE A RELATIVE LULL IN THE PRECIPITATION THREAT WEDNESDAY
NIGHT, BEFORE ANOTHER FRONT MAY SETTLE INTO THE AREA TOWARDS THE
END OF THE EXTENDED. WILL HOLD ONTO POPS IN THE THURSDAY TO
SATURDAY TIME FRAME, BUT AT THIS POINT, IT APPEARS THE BETTER
PRECIPITATION THREAT MAY BE NEXT FRIDAY AND SATURDAY.
AVIATION /DISCUSSION FOR THE 191200Z TAFS/
ISSUED AT 635 AM EDT SUN MAY 19 2019
SHORT TERM MODEL DATA SUGGEST AN AREA OF ORGANIZED LIFT MOVING OUT
OF THE ARKANSAS REGION WILL BE MOVING OVER THE TERMINALS FROM THE
LATE MORNING INTO THE MID AFTERNOON HOURS. FAIRLY WIDESPREAD
RAIN, AND POSSIBLY SOME EMBEDDED LIGHTNING STRIKES, IS EXPECTED IN
THE VICINITY OF THE TERMINALS DURING THOSE TIMES. BRIEF IFR
VISIBILITY RESTRICTIONS IN THE HEAVIER PRECIPITATION.
AN ADDITIONAL THREAT FOR SCATTERED CONVECTION MAY DEVELOP OVER THE
WESTERN TERMINALS TOWARDS EVENING AS A COLD FRONT MOVES IN FROM
ILLINOIS.
OTHERWISE, AREAS OF MVFR CEILINGS 015-030 EXPECTED TO MOVE IN FROM
THE SOUTHWEST TOWARDS THE LATE MORNING HOURS. SURFACE WINDS
190-210 DEGREES WITH OCCASIONAL TO FREQUENT GUSTS AROUND 25 KTS BY
THE MID MORNING HOURS. GUSTS IN EXCESS OF 30 KTS POSSIBLE BY THE
MID TO LATE AFTERNOON HOURS.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....JAS
AVIATION...JAS
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