Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 181805
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
205 PM EDT THU SEP 18 2014

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

&&

.SYNOPSIS...
ISSUED AT 1255 PM EDT THU SEP 18 2014

HIGH PRESSURE OVER ONTARIO WILL KEEP QUIET WEATHER IN PLACE ACROSS
INDIANA TONIGHT. A RIDGE ALOFT OF HIGH PRESSURE OVER THE ROCKY
MOUNTAINS IS EXPECTED TO BUILD EAST INTO THE OHIO VALLEY ON FRIDAY
THROUGH SATURDAY...PROVIDING DRY WEATHER. TEMPERATURES WILL WARM
UP SLIGHTLY THROUGH THE FIRST PART OF THE WEEKEND AS THE SURFACE
HIGH SHIFTS EASTWARD AND WARMER AIR ARRIVES ON SOUTHERLY WINDS.

A WEAK COLD FRONT IS EXPECTED TO PUSH ACROSS THE REGION ON LATE
SATURDAY NIGHT AND EARLY SUNDAY...BRINGING CHANCES FOR RAIN THEN.
ANOTHER HIGH PRESSURE IS THEN EXPECTED TO ARRIVE IN THE REGION FOR
SUNDAY NIGHT AND MONDAY KEEPING DRY WEATHER ACROSS CENTRAL INDIANA
THROUGH THE MIDDLE OF THE NEXT WORK WEEK ALONG WITH NEAR NORMAL TEMPERATURES.

&&

.NEAR TERM /TONIGHT/...

ISSUED AT 1255 PM EDT THU SEP 18 2014

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS A BROAD AREA HIGH
PRESSURE CENTERED OVER ONTARIO DOMINATING WEATHER ACROSS INDIANA
AND THE OHIO VALLEY. COOL AND DRY NORTHEAST SURFACE FLOW WAS IN
PLACE ACROSS INDIANA WITH SURFACE DEW POINT TEMPS IN THE UPPER 40S.

MAIN FORECAST CHALLENGE TONIGHT WILL BE TEMPS.

THE HIGH PRESSURE SYSTEM OVER ONTARIO IS EXPECTED TO DIVE SE
TOWARD NEW ENGLAND TONIGHT...AND THIS WILL RESULT IN OUR LIGHT
NORTHEASTERLY FLOW ACROSS THE AREA TO BECOME MORE SOUTHEAST AND
SOUTHERLY FOR FRIDAY AND FRIDAY NIGHT. FORECAST SOUNDINGS CONTINUE
TO INDICATE A DRY COLUMN AND TIME HEIGHTS CONTINUE TO SHOW SUBSIDENCE
...THUS A MOSTLY CLEAR SKY WILL BE EXPECTED ALONG WITH THE LIGHT
NORTHEAST WINDS.

GIVEN OUR EXPECTED DEW POINTS IN THE MIDDLE 40S WILL TREND LOWS AT
OR BELOW PERSISTENCE GIVEN OUR IDEAL RADIATIONAL COOLING SET-UP.


&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...

ISSUED AT 1255 PM EDT THU SEP 18 2014

MAIN WEATHER CHALLENGE DURING THIS PERIOD WILL BE POPS. MODELS ARE
IN PRETTY GOOD AGREEMENT DURING THIS PERIOD AND WILL USE A BLEND.

WATER VAPOR IMAGERY SHOWS RIDGING IN PLACE OVER THE ROCKY
MOUNTAINS THIS AFTERNOON. GFS/NAM SUGGEST THIS RIDGING IS EXPECTED
TO PUSH EASTWARD AND FLATTEN THROUGH SATURDAY...KEEPING ANY UPPER
LEVEL DYNAMICS WELL NORTH OF CENTRAL INDIANA OVER THE GREAT LAKES.
MEANWHILE AT THE SURFACE THE LARGE HIGH PRESSURE SYSTEM IS
EXPECTED TO PUSH TO NEW ENGLAND BY FRIDAY AFTERNOON AND OUT TO THE
ATLANTIC ON SATURDAY. HOWEVER THE HIGH CONTINUES TO PUSH A LARGE
SURFACE RIDGE WEST...ACROSS THE VIRGINIAS AND INTO THE TENNESSEE
RIVER VALLEY. FORECAST SOUNDINGS AND TIME HEIGHTS REMAIN DRY
THROUGH SATURDAY AFTERNOON...WITH UNATTAINABLE CONVECTIVE TEMPS.
THUS WILL USE A DRY FORECAST UNTIL THEN WITH PARTLY CLOUDY DAYS
AND MOSTLY CLEAR NIGHTS. AS THE HIGH PRESSURE SYSTEM PUSHES
EAST...WARM AIR WILL ARRIVE IN CENTRAL INDIANA ON SOUTHERLY WINDS.
THICKNESSES AND 850MB TEMPS CLIMB DURING THIS TIME. THUS WILL
TREND HIGHS AT OR ABOVE MAV EACH DAY.

ON SATURDAY NIGHT THE GFS AND NAM SUGGEST A COLD FRONT PUSHING OUT
OF THE UPPER MIDWEST AND INTO CENTRAL INDIANA. FORECAST SOUNDINGS
FAIL TO SHOW DEEP SATURATION...BUT DO NOT SHOW A COMPLETELY DRY
COLUMN EITHER. 310K ISENTROPIC SURFACE SHOWS SOME MOISTURE
ARRIVING ALONG THE SURFACE...OVER 6 G/KG...HOWEVER ISENTROPIC LIFT
IS MARGINAL TO POOR. SURFACE CONVERGENCE APPEARS VERY GOOD HOWEVER
AS A GOOD WIND SHIFT AND SHARP TROUGH IS EXPECTED WITH THE FRONT.
THUS EXPECT AT LEAST SOME KING OF LIGHT AMOUNTS OF PRECIP TO BREAK
OUT. WILL TREND POPS TO THE HIGH CHANCE OR LOW LIKELY CATEGORIES
FOR SATURDAY NIGHT AND EARLY SUNDAY. SOME CLEARING IS EXPECTED ON
SATURDAY AFTERNOON AS THE THE FRONT SHOULD BE CLEARING THE STATE
AND HIGH PRESSURE OVER THE NORTHERN PLAINS BEGINS TO BUILD ACROSS
THE AREA.

GIVEN THE EXPECTED CLOUDS AND RAIN...WILL TREND LOWS ON SATURDAY
NIGHT WARMER THAN MAVMOS AND HIGHS ON SUNDAY COOLER THAN MEXMOS.


&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 350 AM EDT THU SEP 18 2014

A COLD FRONT MOVING THROUGH CENTRAL INDIANA WILL KEEP CHANCES FOR
THUNDERSTORMS IN THE FORECAST ON SUNDAY. MODELS HAVE BEEN TRENDING
FASTER WITH THIS FEATURE SO TOOK OUT ANY LINGERING POPS ON SUNDAY
NIGHT. THE REMAINDER OF THE LONG TERM LOOKS DRY WITH UPPER RIDGING
OVERHEAD AND HIGH PRESSURE AT THE SURFACE. TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGHOUT.

&&

.AVIATION /DISCUSSION FOR THE 181800Z TAFS/...
ISSUED AT 1251 PM EDT THU SEP 18 2014

SCATTERED DIURNAL CLOUD COVER BASED AROUND 040 EXPECTED TO DISSIPATE
AROUND SUNSET.

BASED ON EXPECTED CROSSOVER TEMPERATURES...PATCHY MVFR VISIBILITY
RESTRICTIONS MAY DEVELOP IN THE RURAL AREAS TOWARDS 190600Z.

SURFACE WINDS 050-070 AT 6-8 KTS THIS AFTERNOON WILL DIMINISH TO 6
KTS OR LESS AFTER SUNSET.


&&

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

$$

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

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