Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 311827
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
227 PM EDT FRI OCT 31 2014

.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 222 AM EDT FRI OCT 31 2014

A STRONG COLD FRONT IS EXPECTED TO PUSH ACROSS CENTRAL INDIANA
THIS AFTERNOON...ALLOWING MUCH COLDER CANADIAN AIR ACROSS CENTRAL
INDIANA FOR TONIGHT AND INTO THE FIRST PART OF THE WEEKEND. SOME
SHOWERS WILL BE POSSIBLE TODAY AHEAD OF THE FRONT...AND EVEN A FEW
LIGHT SNOW SHOWERS WILL BE POSSIBLE IN THE WAKE OF THE FRONT THIS
EVENING. BY SATURDAY MORNING...CENTRAL INDIANA WILL HAVE HAD A
KILLING FREEZE.

COOL HIGH PRESSURE IS EXPECTED OVER THE REGION ON SUNDAY AND INTO
MONDAY WITH DRY WEATHER AND BELOW NORMAL TEMPERATURES. BY MONDAY
NIGHT AND TUESDAY...WARMER TEMPERATURES ARE EXPECTED TO ARRIVE ON
SOUTHERLY WINDS ON THE BACKSIDE OF HIGH PRESSURE...HOWEVER ANOTHER
APPROACHING COOL FRONT WILL RESULT IN MORE CHANCES FOR RAIN.

&&

.NEAR TERM /THIS AFTERNOON/...

ISSUED AT 1152 AM EDT FRI OCT 31 2014

SPEED UP THE MIX WITH SNOW ACROSS OUR NORTHWEST COUNTIES AS
MONTICELLO WAS NOW REPORTING LAKE EFFECT SNOW SHOWERS THERE.
OTHERWISE...LOWERED INITIAL TEMPERATURES PER OBSERVATIONS. UPDATED
THE GRIDS AS WELL AS THE HAZARDOUS WEATHER OUTLOOK TO REFLECT THIS.

PREVIOUS DISCUSSION FOLLOWS...

SURFACE ANALYSIS EARLY THIS MORNING SHOWS A STRONG AREA OF LOW
PRESSURE OVER THE GREAT LAKES WITH A POORLY DEFINED YET STRONG COLD
FRONT STRETCHING SOUTH ACROSS EASTERN WISCONSIN...EASTERN
ILLINOIS TO THE LOWER MISSISSIPPI RIVER VALLEY. STRONG AND COLD
HIGH PRESSURE WAS FOUND OVER THE UPPER MIDWEST. MUCH COLDER AIR
WAS FOUND IN THE WAKE OF THE FRONT...WITH TEMPS IN THE 30S AND LOW
40S ACROSS WISCONSIN...IOWA AND MINNESOTA. ALOFT...WATER VAPOR
SHOWED A STRONG RIDGE IN PLACE OVER THE ROCKIES AND A DEEP BROAD
TROUGH IN PLACE ACROSS THE EASTERN HALF OF THE UNITED STATES. A
STRONG UPPER LEVEL DISTURBANCE WAS EMBEDDED IN THE FLOW ALOFT OVER
WESTERN LAKE SUPERIOR AND WAS DIVING SOUTHEAST. RADAR SHOWS A FEW
SCATTERED RAIN SHOWERS OVER SOUTHERN CENTRAL INDIANA...ALONG WITH
A FEW MORE VERY LIGHT RAIN SHOWERS OVER CENTRAL ILLINOIS.

GFS AND NAM SUGGEST VERY STRONG COLD AIR ADVECTION TO START
SHORTLY AFTER 12Z TODAY WITH 850MB TEMPS FALLING TOWARD -6C BY 00Z
SAT. GIVEN THIS WE WILL EXPECT STEADY OR SLOWLY FALLING
TEMPERATURES THROUGH THE DAY TODAY. WILL AIM FOR HIGH TEMPS FOR
TODAY OCCURRING AT OR SHORTLY AFTER 12Z...AHEAD OF THE FRONT.
FURTHERMORE THE STRONG PRESSURE GRADIENT BUILDING ACROSS THE WILL
RESULT IN GUSTY NORTH WINDS WITH WIND CHILLS AROUND 30 THIS
AFTERNOON AND IN THE MIDDLE 20S TONIGHT.

AS FOR PRECIP...LIMITED MOISTURE APPEARS IN PLACE WITH TODAY/S
SYSTEM...HOWEVER STRONG FORCING AND DYNAMICS ARE IN PLACE AS THIS
SYSTEM PASSES. BEST MOISTURE APPEARS TO BE PASSING NEAR FRONTAL
PASSAGE AROUND 12Z. FORECAST SOUNDINGS APPEAR TO DRY OUT LATE THIS
MORNING AND THIS AFTERNOON AS NORTHERLY FLOW RESUMES. HOWEVER BY
LATE THIS AFTERNOON AND NEAR 00Z A SECOND BATCH OF PRECIP WILL BE
POSSIBLE AS THE MODELS SUGGEST THE PREVIOUSLY MENTIONED STRONG
UPPER LEVEL DISTURBANCE WILL DIVE ACROSS CENTRAL INDIANA. BY
00Z...FORECAST SOUNDINGS SHOW GOOD SATURATION IN THE LOWER AND MID
LEVELS...ALL WHILE AN 850MB JET OF 50+ KNOTS SCREAMS ALOFT.
FURTHERMORE BY 00Z FORECAST SOUNDINGS SHOW JUST ABOUT THE ENTIRE
COLUMN BELOW 0C...GIVING US A SNOW PROFILE.

STILL...MOISTURE APPEARS LIMITED AS THESE TWO FORCING MECHANISMS
PASS...THUS WILL TREND TOWARD HIGHER POPS THAN MAVMOS BUT
EXPECTING LIGHT AMOUNTS OF PRECIP.

&&

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

ISSUED AT 222 AM EDT FRI OCT 31 2014

GFS AND NAM CONTINUE TO SUGGEST ACTIVE WEATHER ONGOING DURING THE
EVENING HOURS AS THE STRONG UPPER DISTURBANCE WILL CONTINUE TO BE
PASSING THROUGH INDIANA AT 00Z BEFORE EXITING TO THE SOUTHEAST
SHORTLY AFTER 06Z. AGAIN...FAVORABLE CONDITIONS WILL EXIST FOR
PRECIP DURING THE FIRST FEW HOURS AFTER 00Z AS FORECAST SOUNDINGS
REMAIN SATURATED FOR THE FIRST FEW HOURS AFTER 00Z...BEFORE DRYING
OUT RAPIDLY AS THE UPPER LOW AND STRONG WINDS ALOFT DEPART
QUICKLY. DEEP MOISTURE REMAINS LIMITED WITH NORTHERLY FLOW...BUT
STRONG DYNAMICS SHOULD BE ABLE TO PRODUCE SOME LIGHT PRECIP. WARM
GROUND SHOULD RESULT IN ANY SNOW MELTING UPON REACHING THE
GROUND. THUS WILL TREND AT OR SLIGHTLY ABOVE MAVMOS POPS FOR A FEW
HOURS THIS EVENING BEFORE DROPPING POPS OFF QUICKLY BY 06Z AS THE
FORCING MECHANISM EXITS.

EVENING HOURS WILL BE BLUSTERY...WITH SNOW SHOWERS OR ICE PELLETS
POSSIBLE AMID WIND GUSTS OF 20 TO 30 MPH PRODUCING WIND CHILLS TO
NEAR 25 DEGREES. FOLKS WHO WILL BE OUTSIDE THIS EVENING WILL GET A
TASTE OF EARLY WINTER...AND WILL ISSUE AN SPS TO ADDRESS THIS.

AS FOR LOWS...GIVEN THE STRONG COLD AIR ADVECTION...THE FREEZE
WARNING REMAINS A GOOD BET...WITH A HARD FREEZE EXPECTED BY 12Z SAT.

DRY WEATHER WILL THEN BE EXPECTED ON SATURDAY THROUGH MONDAY AS
THE GFS AND NAM SUGGESTS THE STRONG RIDGE OVER THE ROCKIES WILL
PUSH EAST AND BUILD ACROSS THE CENTRAL PLAINS AND THEN THE OHIO
VALLEY BY MONDAY...WITH THE RIDGE AXIS OVER INDIANA BY 18Z MONDAY.
FORECAST SOUNDINGS THROUGH THIS PERIOD SHOW A DRY COLUMN WITH
UNREACHABLE CONVECTIVE TEMPS WITH GOOD SUBSIDENCE IN PLACE. THUS
WILL TREND TOWARD MOSTLY SUNNY DAYS AND MOSTLY CLEAR NIGHT DURING
THIS PERIOD. AS FOR TEMPS WILL TREND BOTH HIGHS AND LOWS COOLER
THAN MAVMOS ON SATURDAY AND SATURDAY NIGHT. HOWEVER BY SUNDAY
SOUTHERLY FLOW RETURNS AMID SOME WARM AIR ADVECTION ALOFT. WILL
STICK CLOSE TO MAVMOS LOWS AND HIGHS SUNDAY THROUGH MONDAY NIGHT.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 227 PM EDT FRI OCT 31 2014

GIVEN RELATIVELY HIGH UNCERTAINTY...THE SUPERBLEND INITIALIZATION
WAS ACCEPTED FOR MOST ITEMS.

AN UPPER TROUGH WILL MOVE THROUGH THE AREA DURING THE LONG
TERM...BUT MODELS DIFFER ON HOW FAST IT EXITS THE AREA. ALSO...00Z
ECMWF AND 12Z DIFFER EXTENSIVELY ON HOW AN UPPER LOW IS HANDLED
ACROSS THE SOUTHWEST USA. THUS CONFIDENCE IS LOW IN LONG TERM.

A COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION MONDAY NIGHT INTO
WEDNESDAY...AND THIS WILL KEEP CHANCES FOR RAIN IN THE FORECAST
DURING THAT TIME. HIGH PRESSURE SHOULD MOVE IN FOR THE END OF THE
WEEK SO WENT DRY THEN.

TEMPERATURES LOOK TO REMAIN NEAR AVERAGE TO ABOVE AVERAGE FOR MOST
OF THE PERIOD...BUT THEY WILL COOL DOWN BY FRIDAY.

&&

.AVIATION /DISCUSSION FOR THE 311800Z TAF ISSUANCE/...
ISSUED AT 1255 PM EDT FRI OCT 31 2014

MVFR CONDITIONS THROUGH FIRST HALF OF THE PERIOD...WITH VFR FOR
SECOND HALF. GUSTY WINDS THROUGHOUT...WITH STRONGEST GUSTS BEFORE
06Z.

SECONDARY SURFACE TROUGH WILL MOVE THROUGH THE SITES THIS AFTERNOON.
WIND GUSTS WILL INCREASE AS THIS PASSES WITH GUSTS OVER 30KT COMMON.
SCATTERED TO NUMEROUS SHOWERS WILL MOVE ACROSS THE AREA. AS
TEMPERATURES FALL...SOME SNOW SHOWERS COULD MIX IN AT ALL SITES.

HEAVIER SNOW SHOWERS FROM LAKE MICHIGAN MAY IMPACT KLAF AND REDUCE
VISIBILITY TO IFR BRIEFLY...BUT CONFIDENCE IS TOO LOW TO ADD TO THE
TAF AT THIS TIME.

AS SYSTEM MOVES EAST OVERNIGHT CONDITIONS WILL IMPROVE TO VFR. AM
GOING PESSIMISTIC IN KEEPING CLOUD COVER IN THROUGH THE NIGHT AS
MODELS MAY CLEAR THINGS OUT TOO FAST.

SATURDAY WILL SEE VFR CONDITIONS WITH WIND GUSTS NEAR 20KT AS HIGH
PRESSURE BUILDS IN.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING FROM MIDNIGHT TONIGHT TO 10 AM EDT SATURDAY FOR
INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA/MK
SHORT TERM...PUMA
LONG TERM....50
AVIATION...50

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