Area Forecast Discussion
Issued by NWS Indianapolis, IN

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KIND 291733
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1230 PM EST THU JAN 29 2015

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 311 AM EST THU JAN 29 2015

AN AREA OF LOW PRESSURE WILL DRAG A COLD FRONT THROUGH CENTRAL
INDIANA TODAY...BRINGING A CHANCE FOR RAIN. ANOTHER LOW PRESSURE
SYSTEM COULD BRING ACCUMULATING SNOW TO THE AREA SATURDAY NIGHT INTO
SUNDAY NIGHT. MUCH COLDER AIR WILL MOVE INTO THE AREA EARLY NEXT
WEEK.

&&

.NEAR TERM.../TODAY/
ISSUED AT 311 AM EST THU JAN 29 2015

A BROKEN LINE OF LIGHT RAIN SHOWERS WAS MOVING ACROSS CENTRAL
INDIANA EARLY THIS MORNING. THIS IS IN AN AREA OF LIFT WELL AHEAD OF
THE SURFACE FRONT THAT WAS MOVING INTO WESTERN ILLINOIS.

THE SPEED OF THIS BAND OF RAINFALL WILL PUT IT OUT OF THE AREA BY
12Z...AND HI RES SHORT TERM MODELS HAVE LITTLE BEHIND IT. WILL GO
CHANCE POPS WITH THIS LINE BEFORE 12Z...AND MAINLY SLIGHT CHANCE
POPS AT 12Z.

CHANCES FOR RAIN WILL INCREASE ONCE AGAIN MID MORNING WITH THE
APPROACH OF THE SURFACE FRONT AND THE ARRIVAL OF AN UPPER TROUGH.
HOWEVER NEITHER FORCING NOR MOISTURE LOOK IMPRESSIVE. WILL JUST GO
CHANCE POPS THAT WILL PEAK AROUND 17Z. AS THE FRONT AND TROUGH MOVE
EAST THIS AFTERNOON...WILL DECREASE POPS FROM WEST TO EAST.

ALTHOUGH TEMPERATURES ALOFT COOL QUICKLY THIS AFTERNOON...BOUNDARY
LAYER TEMPERATURES WILL COOL SLOWER. THUS ONLY ADDED A MIX OF SNOW
WITH THE RAIN LATE THIS AFTERNOON.

BASED ON UPSTREAM TEMPERATURES AND SHORT TERM GUIDANCE...WENT CLOSER
TO THE WARMER OF THE MOS HIGHS AT MANY LOCATIONS.  WINDS WILL BE
GUSTY TODAY AS SOME OF THE STRONGER WINDS ALOFT MIX DOWN.

&&

.SHORT TERM.../TONIGHT THROUGH SATURDAY NIGHT/
ISSUED AT 311 AM EST THU JAN 29 2015

FOCUS IS ON SKY COVER EARLY THEN ON CHANCES FOR PRECIPITATION LATE
IN THE PERIOD. MODELS ARE CLOSE ENOUGH FOR THE MOST PART THAT A
BLEND WAS USED. HOWEVER...CONFIDENCE IN MODELS IS QUITE LOW FOR THE
SYSTEM MOVING IN SATURDAY NIGHT.

SOME LAKE EFFECT SNOW SHOWERS MAY GET INTO THE NORTHEAST FORECAST
AREA TONIGHT SO KEPT LOW POPS THERE. ELSEWHERE WENT DRY. BELIEVE
MODELS ARE CLEARING SKIES OUT TOO FAST...ESPECIALLY WHEN LOOKING AT
SATELLITE IMAGES EARLY THIS MORNING. THUS KEPT SKIES MOSTLY
CLOUDY ACROSS THE AREA TONIGHT.

WITH THE HIGHER SKY COVER WENT CLOSE TO THE WARMER MET MOS NUMBERS
FOR LOW TEMPERATURES.

CLOUDS WILL GRADUALLY DECREASE ACROSS THE SOUTHWEST FORECAST AREA
FRIDAY...BUT THE NORTHEAST FORECAST AREA WILL LIKELY REMAIN MOSTLY
CLOUDY FOR MUCH OF THE DAY THANKS IN PART TO CLOUDS OFF OF LAKE
MICHIGAN. AT THE MOMENT DO NOT BELIEVE ANY LAKE EFFECT SNOW SHOWERS
WILL MAKE IT TO CENTRAL INDIANA. WENT WITH A BLEND OF MODELS FOR
HIGH TEMPERATURES.

FRIDAY NIGHT AND SATURDAY WILL BE PARTLY CLOUDY WITH HIGH PRESSURE
MOVING ACROSS THE AREA.

FORCING WILL MOVE INTO THE AREA SATURDAY NIGHT AHEAD OF THE NEXT LOW
PRESSURE SYSTEM. MODELS KEEP CHANGING THEIR SOLUTIONS ON PHASING AND
THE STRENGTH/TRACK OF THE LOW PRESSURE SYSTEM. HAVE SEEN MANY TIMES
THIS WINTER THE POOR PERFORMANCE OF THE MODELS WITH THESE TYPE OF
SYSTEMS...ESPECIALLY THIS FAR OUT IN THE FORECAST. THUS CONFIDENCE
IS QUITE LOW...SO ONLY WENT CHANCE POPS SATURDAY NIGHT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
ISSUED AT 311 AM EST THU JAN 29 2015

PRIMARY FOCUS FOR THE EXTENDED PERIOD REMAINS ON THE POTENTIAL FOR A
HIGH IMPACT WINTER STORM TO MOVE THROUGH THE OHIO VALLEY SUNDAY AND
SUNDAY NIGHT.

MODEL GUIDANCE CONTINUES TO TEST FORECASTER PATIENCE AS RUN TO RUN
VARIANCE SWINGS WILDLY WITH THE POTENTIAL LATE WEEKEND WINTER STORM.
AFTER 28/12Z GUIDANCE TRENDED AWAY FROM A MORE PHASED SYSTEM...00Z
GUIDANCE HAS BROUGHT GREATER IMPACTS BACK INTO THE REGION. GEM AND
OP GFS BOTH BRING A MORE PHASED UPPER WAVE ACROSS THE OHIO VALLEY
WHILE THE ECMWF BRINGS THE SYSTEM FURTHER NORTH THAN ITS PREVIOUS
RUN BUT REMAINS MORE SUPPRESSED THAN THE OTHER MODELS. THIS IS
LIKELY DUE TO HOLDING THE NORTHERN STREAM ENERGY BACK LONGER
RESULTING IN A MORE DELAYED PHASING OF THE UPPER JETS UNTIL AFTER
THE SYSTEM PASSES BY CENTRAL INDIANA.

THE MAIN PLAYER IS THE PHASING OF THE POLAR JET DIVING DOWN THE
EAST SIDE OF THE ROCKIES AND INTERACTING WITH A STRONG SUBTROPICAL
JET TRANSPORTING PACIFIC MOISTURE AS IT TRACKS OUT OF NORTHERN
MEXICO. MODELS CONTINUE TO STRUGGLE WITH DEGREE AND LOCATION OF
THE PHASING JET ENERGY ALOFT AND UNTIL A MORE SUBSTANTIAL
CONSENSUS CAN BE REACHED...SUSPECT MODELS WILL CONTINUE TO SHIFT
THE TRACK OF THE SURFACE WAVE BACK AND FORTH FOR AT LEAST ANOTHER
DAY OR TWO UNTIL SOME OF THE UPPER JET ENERGY IS MORE COMPLETELY
SAMPLED. THE VARIANCE IN SURFACE WAVE TRACKS THAT THE INDIVIDUAL
GFS ENSEMBLE MEMBERS CONTINUE TO EXHIBIT FURTHER SUPPORTS THAT
THINKING. IT IS FOR THESE REASONS THAT CONFIDENCE REMAINS LOW ON
THE DETAILS AT THIS POINT IN TIME.

WITH THAT BEING SAID...SOME TRENDS DEFINITELY STARTING TO SHOW
OVER THE COURSE OF THE LAST 36-48 HOURS. SETUP IS COLDER ACROSS
THE BOARD WITH GROWING CONFIDENCE THAT PRECIP TYPE MAY BE A NON-
ISSUE IF THE SURFACE WAVE TRACK ENDS UP NEAR THE CURRENT CONSENSUS
ACROSS THE TENNESSEE/LOWER OHIO VALLEYS. MODELS SENDING COPIOUS
AMOUNTS OF PACIFIC/GULF MOISTURE INTO THE OHIO VALLEY...SETTING
UP A BROAD AND POTENTIALLY EXTENDED PERIOD OF OVERRUNNING
PRODUCING MODERATE SNOWFALL ACROSS PORTIONS OF THE REGION BY EARLY
MONDAY. LOW LEVEL THERMAL ANALYSIS SUPPORTS POTENTIAL FOR ENHANCED
SNOWFALL RATIOS AS THE EVENT UNFOLDS...POSSIBLY APPROACHING 20 TO
1 BY SUNDAY NIGHT AS ARCTIC AIR RAPIDLY SPILLS INTO THE REGION. IT
REMAINS PREMATURE TO DELVE INTO ACCUMULATION SPECIFICS BUT AS HAS
BEEN STATED THE LAST COUPLE DAYS...THE SETUP RIGHT NOW CERTAINLY
SUPPORTS POTENTIAL FOR SEVERAL INCHES OF ACCUMULATION ACROSS
CENTRAL INDIANA. STAY TUNED AS MORE MODEL VARIANCE LIKELY
FORTHCOMING.

REMAINDER OF THE EXTENDED MORE STRAIGHTFORWARD AS A DEEP UPPER
TROUGH WILL SETTLE ACROSS THE EASTERN PART OF THE COUNTRY WITH
COLD TEMPS. A QUICK MOVING UPPER LEVEL WAVE WILL SWING ACROSS THE
REGION TUESDAY NIGHT AND WEDNESDAY AND MAY BRING A ROUND OF LIGHT
SNOW. POTENTIAL EXISTS FOR EVEN COLDER WEATHER BY LATE NEXT WEEK
AS 500MB HEIGHTS POISED TO TUMBLE WITH A SHARP UPPER LOW DIVING
SOUTH OF JAMES BAY.

&&

.AVIATION /DISCUSSION FOR 291800Z TAF ISSUANCE/...
ISSUED AT 1230 PM EST THU JAN 29 2015

LATEST VIS SAT IMAGERY INDICATING EXTENSIVE AREA OF CLOUD COVER OVER
MUCH OF THE REGION BEHIND DEPARTING LOW PRESSURE SYSTEM. EXPECT MVFR
CEILINGS TO PERSIST THROUGH THE TAF CYCLE. GUSTY NW WINDS WILL ALSO
PERSIST AS STRONG GRADIENT REMAINS IN PLACE THROUGH MUCH OF THE
PERIOD. LIGHT RETURNS ON KIND RADAR IN ASSOCIATION WITH SMALL AREA
OF MVFR VSBYS ALSO NOTED...THESE ONLY EXTEND BACK TO KCMI SO WILL
COVER WITH 1HR TEMPO TO BEGIN THE TAF PERIOD. FORECAST SOUNDINGS
INDICATING LOW LEVEL MOISTURE WILL REMAIN TRAPPED UNDER SHALLOW
INVERSION AT 3KFT LENDING FURTHER SUPPORT TO PERSISTENT MVFR CIGS
THRU THIS CYCLE. WEAKENING GRADIENT WILL ALLOW FOR DIMINISHING WINDS
IN OUT PERIOD OF KIND TAF.

&&

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

&&

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM...RYAN
AVIATION...JAL

VISIT US AT HTTP://WWW.WEATHER.GOV/IND

FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSINDIANAPOLIS
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.