Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 300617
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
217 AM EDT SAT MAY 30 2015

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

&&

.SYNOPSIS...
ISSUED AT 217 AM EDT SAT MAY 30 2015

AN UPPER LEVEL WEATHER DISTURBANCE ARRIVING FROM THE SOUTHERN
PLAINS ALONG WITH A COLD FRONT PUSHING THROUGH THE OHIO VALLEY
WILL RESULT IN CHANCES FOR RAIN SHOWERS AND THUNDERSTORMS
TODAY...PARTICULARLY THIS AFTERNOON AND TONIGHT.

A FEW SHOWERS WILL LINGER ON SUNDAY MORNING AS THE LOW DEPARTS TO
THE EAST. BY SUNDAY AFTERNOON...COOLER NORTHERLY FLOW ASSOCIATED
WITH HIGH PRESSURE IN THE WAKE OF THE LOW WILL BRING A RETURN OF
DRY WEATHER...BUT COOLER TEMPERATURES.

HIGH PRESSURE IS THEN SET TO REMAIN ACROSS THE AREA THROUGH THE
MIDDLE OF NEXT WEEK...BRINGING DRY AND COOLER WEATHER.

&&

.NEAR TERM /TODAY/...

ISSUED AT 217 AM EDT SAT MAY 30 2015

SURFACE ANALYSIS EARLY THIS MORNING SHOWS A BROAD TROUGH OF LOW
PRESSURE STRETCHING FROM THE GREAT LAKES...ACROSS ILLINOIS TO THE
SOUTHERN PLAINS. WARM AND MOIST SOUTHERLY FLOW REMAINED IN PLACE
ACROSS CENTRAL INDIANA AHEAD OF THE TROUGH. DEW POINTS WERE
HOLDING IN THE MOIST MIDDLE 60S. WATER VAPOR IMAGERY SHOWED A
SHORT WAVE ACROSS MISSOURI AND ARKANSAS PUSHING NORTHEAST. RADAR
SHOWS SOME SCT CONVECTION ACROSS ILLINOIS AND MISSOURI...ALBEIT IT
WAS ONLY GARDEN VARIETY SHOWERS AND STORMS.

MAIN FORECAST CHALLENGE TODAY WILL BE POPS. FORECAST SOUNDINGS AND
TIME HEIGHTS SHOW DEEP SATURATION ARRIVING BY LATE AFTERNOON. GFS
AND NAM SHOW STRONG FORCING ARRIVING FROM THE SOUTHWEST ALOFT
AFTER 18Z...TIMING WELL WITH DAYTIME HEATING. FORECAST SOUNDINGS
SHOWING AROUND 100 J/KG OF CAPE THIS AFTERNOON WITH PRECIPITABLE
WATER OVER 1.75 INCHES. LOWER LEVEL Q VECTORS SHOW BEST
CONVERGENCE ACROSS CENTRAL AND NORTHERN INDIANA...MAINLY LATE IN
THE DAY AND EARLY THIS EVENING. GIVEN ALL OF THE AVAILABLE
FORCING AND MOISTURE...WILL TREND POPS AT OR ABOVE MAVMOS IN MOST
CASES. AS THE BEST FORCING FAILS TO ARRIVE UNTIL THE
AFTERNOON...WILL TRY AND RAMP UP POPS AS THE DAY PROGRESSES...WITH
THE MOST DRY HOURS ACROSS THE EASTERN PARTS OF THE FORECAST AREA.

AS FOR TEMPS...WILL ONCE AGAIN TREND TOWARD
PERSISTENCE...ESPECIALLY IN THE EAST WHERE PRECIPITATION SHOULD
HOLD OFF THE LONGEST.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...

ISSUED AT 217 AM EDT SAT MAY 30 2015

WET WEATHER LOOKS IN STORE FOR TONIGHT AS THE PREVIOUSLY
MENTIONED UPPER SHORT WAVE WILL BE PUSHING ACROSS INDIANA
OVERNIGHT. GFS AND NAM ALSO SUGGEST THE SURFACE LOW WILL TRACK
ACROSS CENTRAL INDIANA...A BIT FARTHER NORTH THAN PREVIOUS
RUNS...WHICH MAY RESULT IN THE HEAVIER AMOUNTS OF RAIN BEING
FOCUSED ACROSS THE NORTHERN PARTS OF CENTRAL INDIANA. STILL ALL
AREA SHOULD GET SOME PRECIP THIS EVENING AS THIS SYSTEM PASSES.
VERY GOOD LOWER LEVEL CONVERGENCE REMAINS ACROSS THE AREA AS THIS
SYSTEM PASSES. TIME HEIGHTS ALSO SHOW BEST FORCING AT 00Z THROUGH
ABOUT 06Z AS FORCING ALOFT PASSES. FORECAST SOUNDINGS SHOW DEEP
SATURATION. THUS WILL TREND TOWARD 100 POPS FOR MOST AREAS. ALONG
WITH TEMPS WARMER THAN MAVMOS GIVEN THE EXPECTED CLOUDS AND RAIN.

TIME HEIGHT SECTIONS SHOW FORCING ENDING QUICKLY ON SUNDAY
MORNING AS THE THE GFS AND NAM DEPICT THE SHORT WAVE ALOFT EXITING
QUICKLY. SOME TIME HEIGHTS CONTINUE TO SHOW SATURATED LOWER LEVELS
AND FORECAST SOUNDINGS SHOW A LAYER OF LOWER LEVEL CLOUD LINGERING
THROUGH THE DAY WITH DRY AIR ALOFT. MEANWHILE AT THE SURFACE...LOW
PRESSURE IS EXPECTED TO EXIT INDIANA AND PUSH TOWARD NORTHEAST
OHIO...KEEPING WEAK CYCLONIC FLOW IN PLACE ACROSS THE AREA ALONG
WITH COLD AIR ADVECTION. GIVEN THE LOSS OF FORCING...HEAVIER RAINS
SHOULD END ON SUNDAY RATHER QUICKLY...BUT GIVEN THE CYCLONIC FLOW
AND LOWER LEVEL CLOUDS...A FEW VERY LIGHT SHOWERS OR DRIZZLE
CANNOT BE RULED OUT. WILL TREND POPS AT OR BELOW
MAVMOS...ESPECIALLY ACROSS THE WEST WHERE FORCING IS LOST THE
SOONEST. AS FOR TEMPS WILL TREND AT OR BELOW MAVMOS GIVEN THE
EXPECTED CLOUD AND COOL NORTH WINDS.

ON SUNDAY NIGHT INTO MONDAY...THE GFS AND NAM SUGGESTS DRY...NW FLOW
IN PLACE ALOFT. MEANWHILE AT THE SURFACE...A LARGE AREA OF HIGH
PRESSURE IN THE WAKE OF THE DEPARTING LOW WILL BE PLACE ACROSS
THE GREAT LAKES...PROVIDING A COOL NORTHEAST FLOW OF DRY
CONTINENTAL FLOW TO INDIANA. FORECAST SOUNDINGS SHOW A DRY COLUMN
IN PLACE ON SUNDAY NIGHT THROUGH MONDAY. MEANWHILE...GOOD
SUBSIDENCE IS SEEN IN THE MIDDLE LEVELS. THUS WILL TREND TOWARD AS
DRY FORECAST DURING THIS PERIOD. AS FOR TEMPS...GIVEN THE COOL
NORTHEAST FLOW...A BLEND OF THE MAVMOS AND METMOS SHOULD WORK NICELY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...

ISSUED AT 223 PM EDT FRI MAY 29 2015

ENSEMBLES ARE SHOWING GOOD AGREEMENT ON AN UPPER RIDGE BUILDING
ACROSS THE AREA THROUGH THE LONG TERM. ENSEMBLES ARE ALSO AGREEING
ON A WESTERN U.S. UPPER LOW DIGGING SOUTH AND GETTING CUT OFF OVER
THE GULF AS THE AFOREMENTIONED RIDGE BUILDS. IN THE OPERATIONAL RUNS
THERE IS A SUGGESTION THAT MOISTURE/UPPER FORCING FROM THIS UPPER
LOW COULD SWING NORTH INTO THE SOUTHERN COUNTIES AND BRING SOME
THUNDERSTORM CHANCES DESPITE THE PRESENCE OF THE UPPER RIDGE
THURSDAY AND FRIDAY. CHANCES WOULD BE MORE LIKELY DURING THE DAY
WITH DAYTIME HEATING AVAILABLE TO HELP THE FORCING OVERCOME THE
INHIBITION OF THE UPPER RIDGE. TEMPERATURES WILL WARM FROM NEAR
NORMAL TO START THE PERIOD TO ABOUT 10 DEGREES ABOVE NORMAL GOING
INTO THE WEEKEND.

&&

.AVIATION /DISCUSSION FOR THE 300600Z TAFS/...
ISSUED AT 1233 AM EDT SAT MAY 30 2015

LEFTOVER CONVECTIION PRIOR TO START OF TAF FORECAST HAS FINALLY
DISSIPATED AFTER INTERACTION WITH OUTFLOW BOUNDARY AND REMAINING
AVAILABLE ENERGY.

POTENTIAL FOR MORE CONVECTION PRETTY CERTAIN OVER CENTRAL INDIANA
LATER TODAY AS SURFACE AND UPPER TROUGH APPROACH FROM THE SOUTHWEST.
WITH RELATIVELY LOW CONVECTIVE TEMPERATURES AND LITTLE CAP MAY START
TO SEE DEVELOPMENT AS EARLY AS 301600Z. HOWEVER NO CLEAR CUT TRIGGER
OR FOCUS AT THIS TIME TO PIN DOWN LOCATION AND TIMING. AS A
RESULT...WILL JUST GO WITH A CB SIGNIFICANT CLOUD IN THE VICINITY OF
THE TERMINALS BY MID DAY WITH BASES AROUND 030. BRIEF IFR VISIBILITY
RESTRICTIONS AND GUSTY/SHIFTING WINDS POSSIBLE IN AND NEAR ANY
CONVECTION AS TERRE HAUTE EXPERIENCED EARLIER FRIDAY EVENING.

MODELS STILL VARY ON TRACK OF SURFACE LOW WHICH DETERMINES HOW WINDS
WILL SHIFT SATURDAY EVENING. IF LOW TRACKS NORTH OF TERMINLAS
SOUTHWEST WINDS SWITCH TO NORTHWEST AND NORTH. IF LOW TRACKS SOUTH
OF TERMINALS...EXPECT SOUTHWEST WIND TO BACK TO SOUTHEAST BEFORE
SWINGING TO NORTH WITH LOWS PASSAGE.

STEADY RAIN WITH EMBEDDED THUNDER EXPECTED FROM 310000Z THROUGH
0900Z-1200Z IN WRAP-AROUND PORTION OF LOW PRESSURE SYSTEM MOVING
THROUGH. CLOUD DECKS WILL DROP TO IFR DURING MODERATE RAIN AS COLDER
AIR DRIVES IN ON NORTH WIND SOMETIME AFTER 310300Z.
NO SIGNIFICANT CHANGE FOR KIND. CUMULUS HAVE DISSIPATED. SMALL
CHANCE KHUF SHOWERS MAY PROGRESS INTO AREA IN SEVERAL HOURS SO
WILL MONITOR.

&&

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

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM....CP
AVIATION...TUCEK

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