Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 130804
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
404 AM EDT SUN APR 13 2014

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

&&

.SYNOPSIS...
ISSUED AT 359 AM EDT SUN APR 13 2014

AN ACTIVE AND CHANGING WEATHER PATTERN IS IN PLACE FOR
THE FORECAST PERIOD WITH WARM BREEZY CONDITIONS TODAY GIVING WAY TO
RAIN AND THUNDERSTORM CHANCES TONIGHT AND MUCH COLDER AIR ADVECTING
IN MONDAY AND MONDAY NIGHT POSSIBLY BRINGING SNOWFLAKES BACK TO THE
AREA. THE COLD TEMPERATURES SHOULD LAST THROUGH MID WEEK AND THEN
START TO MODERATE FOR THE END OF THE WEEK. MORE RAIN CHANCES ARRIVE
NEAR THE END OF THE WEEK.

&&

.NEAR TERM /TODAY/...

ISSUED AT 359 AM EDT SUN APR 13 2014

ANOTHER WARM DAY IN STORE FOR CENTRAL INDIANA UNDER WEAK UPPER
RIDGING AND SOUTHWESTERLY FLOW. EXPECT TO SEE A BIT MORE CLOUD COVER
THAN YESTERDAY WITH ISENTROPIC LIFT OCCURRING BRINGING IN CLOUDS
FROM THE SOUTHWEST AND STORMS TO THE NORTHWEST SPILLING CIRRUS INTO
THE AREA. WITH 850 TEMPERATURES SO WARM AND SURFACE TEMPERATURES
STARTING OUT AROUND 60 THIS MORNING THINK HIGHS WILL BE SIMILAR TO
YESTERDAY SO WENT A LITTLE WARMER THAN THE WARMEST GUIDANCE NUMBERS.
A TIGHTENING PRESSURE GRADIENT AND INCREASING WINDS ALOFT WITH GOOD
MIXING WILL ALLOW SUSTAINED SURFACE WINDS AROUND 20-25 MPH WITH
GUSTS TO AROUND 40 MPH AT THEIR PEAK. THUS WHILE THIS WILL MAKE FOR
A SOMEWHAT WINDY DAY WILL NOT BE STRONG ENOUGH TO JUSTIFY AN
ADVISORY.

STILL LOOKS LIKE AREA WILL STAY DRY THROUGH MUCH OF THE DAY...AND
JUST KEPT SMALL CHANCES IN THE NORTHWEST STARTING AT 21Z IN CASE A
CONVECTIVE CELL OVER ILLINOIS MANAGES TO MAKE PROGRESS INTO THE AREA
OF UPPER RIDGING.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...

ISSUED AT 359 AM EDT SUN APR 13 2014

AN ACTIVE WEATHER PATTERN WILL BE THE RULE FOR THE SHORT TERM. A
COLD FRONT WILL APPROACH TONIGHT AND ISENTROPIC LIFT AHEAD OF THE
FRONT ALONG WITH AN UPPER SHORTWAVE SHOULD ALLOW INCREASING
PROBABILITY FOR RAIN OVERSPREADING THE AREA FROM NORTHWEST TO
SOUTHEAST DURING THE TONIGHT PERIOD. WITH THE TIMING INSTABILITY IS
WANING SO LOOKING AT WIDESPREAD RAIN WITH SOME EMBEDDED
THUNDERSTORMS BUT AT THIS TIME LOOKS TOO ANEMIC FOR ANY SEVERE
THREAT. MODELS ARE SHOWING TIMING DIFFERENCES OF AROUND 3 HOURS FOR
FRONTAL PASSAGE WITH THIS SET SHOWING THE GFS THE FASTEST AND THE
SREFS/NAM/ECMWF CLUSTERED WITH THE SLOWER SOLUTION AND WITH THE
CLUSTERING OF SOLUTIONS AROUND THE SLOWER SOLUTION PREFERRED IT.
THIS MADE A DIFFERENCE IN KEEPING THE HIGHEST POPS AROUND THROUGH
MONDAY MORNING AS WELL AS GOING WITH RAW MODEL TEMPERATURES FOR LOWS
TONIGHT USING A NON-GFS CONSENSUS AND KEEPING SIMILAR TEMPERATURES
FOR HIGHS ON MONDAY BUT WITH A FEW DEGREES OF WARMING ACROSS THE
SOUTHEASTERN HALF OR SO OF THE AREA AHEAD OF FRONTAL PASSAGE.

EVEN IN THE SLOWER SOLUTIONS COLD AIR COMES RUSHING IN ON MONDAY
NIGHT. WITH ANOTHER WAVE BRINGING MORE FORCING TO THE AREA WENT
TOWARD HIGH END OF GUIDANCE POPS FOR MONDAY NIGHT...AND WITH THE
AFOREMENTIONED COLD AIR INCLUDED A TRANSITION TO RAIN AND SNOW
ACROSS SOME OF THE AREA BY 0Z AND THE REST OF THE AREA BY 6Z...WITH
THE NORTHERN COUNTIES EVEN GOING OVER TO ALL SNOW AT THAT TIME. WARM
GROUND SHOULD PRECLUDE ACCUMULATION. MOISTURE MOVES OUT BY TUESDAY
MORNING SO JUST INCLUDED A SLIGHT CHANCE IN THE FAR EAST FOR A FEW
HOURS FOR COLLABORATION PURPOSES. NEAR AND BELOW FREEZING
TEMPERATURES ARE IN THE OFFING FOR MONDAY NIGHT AND TUESDAY
NIGHT...BUT DIDN/T WANT TO DROP OFF THE DEEP END LIKE GUIDANCE IS
DOING ESPECIALLY FOR MONDAY NIGHT WITH AMPLE CLOUD COVER. ENDED UP
WITH LOWS IN THE UPPER 20S TO LOWER 30S. SHOULD BE FAIRLY WINDY
YET MONDAY NIGHT SO MAY NOT SEE MUCH IN THE WAY OF FROST
THEN...BUT TUESDAY NIGHT/WEDNESDAY MORNING LOOKS MUCH MORE CONDUCIVE.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
ISSUED AT 252 AM EDT SUN APR 13 2014

MAIN FOCUS TO THE EXTENDED WILL BE ON TIMING OF POPS LATE NEXT WEEK
AND EARLY NEXT WEEKEND.

MODELS ARE NOT COMING ANYWHERE NEAR A CONSENSUS WITH THE STRENGTH
AND TIMING OF A LATE WEEK AND EARLY WEEKEND LOW PRESSURE SYSTEM WITH
THE 00Z GFS BEING BY FAR THE STRONGEST...LIFTING A SURFACE LOW
PRESSURE SYSTEM NORTHEAST ACROSS ILLINOIS AND INTO THE GREAT LAKES
ON FRIDAY. HOWEVER...ALL THE MODELS ARE REASONABLY CLOSE IN
SUGGESTING BY THEIR QPF FIELDS THAT RAIN SHOWERS WILL MOVE IN FROM
THE WEST BY EARLY FRIDAY...AND DEPART EAST FRIDAY NIGHT. SO...WILL
ACCEPT REGIONAL CHANCE POPS FOR THAT PERIOD THAT REFLECT THE ABOVE
THINKING. THE REST OF THE FORECAST LOOKS DRY AS HIGH PRESSURE BUILDS
IN FROM THE SOUTHWEST. INSTABILITY PROGS ARE NOT STRONGLY SUGGESTING
THUNDER...SO WILL LEAVE IT OUT FOR NOW.

LOW LEVEL THERMAL PROGS AND EXPECTED CLOUD COVER AND WEATHER SUGGEST
NOT DEVIATING MUCH FROM REGIONAL BLEND REGARDING TEMPERATURES WITH
TEMPERATURES RETURNING TO NEAR NORMAL BY THURSDAY AFTER A COOL START
WEDNESDAY.

&&

.AVIATION /DISCUSSION FOR THE 130600Z TAFS/...
ISSUED AT 1221 AM EDT SUN APR 13 2014

THIS EVENING/S UPPER AIR INDICATES 25-30KT WINDS AROUND 020. SHORT
TERM MODEL DATA SUGGEST THE LOW LEVEL JET WILL INCREASE DURING THE
NEXT FEW HOURS...WITH THE POTENTIAL FOR WINDS WITHIN THE JET OF
45-50KT...SUGGESTING THE POTENTIAL FOR LOW LEVEL WIND SHEAR. SURFACE
WINDS HAVE DROPPED OFF FOR NOW...BUT SHOULD PICK UP AGAIN LATER AS
THE LOW LEVEL JET STRENGTHENS. AT THIS TIME...APPEARS BOUNDARY LAYER
WILL REMAIN MIXED UP ENOUGH TO PREVENT MUCH OF A NOCTURNAL INVERSION
FROM DEVELOPING...SO ANY WIND SHEAR SHOULD BE BELOW CRITERIA. WILL
KEEP AN EYE ON SURFACE WIND TRENDS OVERNIGHT.

OTHERWISE...EXPECTING SURFACE WINDS TO BEGIN GUSTING OVER 20 KTS
WITHIN A COUPLE OF HOURS AFTER SUNRISE...WITH POTENTIAL FOR GUSTS
30-32 KTS BY 131800Z. SURFACE WIND DIRECTIONS FROM 190-210 DEGREES.

SOME CLOUD COVER BASED AROUND 050 MAY DEVELOP TOWARDS MIDDAY ON
SUNDAY...WITH HIGHER CLOUDS ABOVE. FINALLY...SHOULD SEE CEILINGS
LOWER AND SHOWERS MOVE IN AFTER 02Z SUNDAY NIGHT. MODELS WERE ALSO
SHOWING PLENTY OF INSTABILITY TO MERRITT VCTS.

&&

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

$$

SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM...MK
AVIATION...JAS/MK

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