Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 191135
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
635 AM EST FRI DEC 19 2014

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

&&

.SYNOPSIS...
ISSUED AT 252 AM EST FRI DEC 19 2014

HIGH PRESSURE WILL KEEP CENTRAL INDIANA DRY THROUGH THE
WEEKEND...EVEN THOUGH UPPER SYSTEMS WILL MOVE ACROSS THE AREA. A
LARGE LOW PRESSURE SYSTEM WILL BRING CHANCES FOR PRECIPITATION
MONDAY THROUGH CHRISTMAS EVE. TEMPERATURES WILL WARM TO ABOVE
AVERAGE BY EARLY NEXT WEEK THEN COOL AGAIN BY MID WEEK.

&&

.NEAR TERM.../TODAY/
ISSUED AT 635 AM EST FRI DEC 19 2014

CLOUD DECK IS MOVING SOUTH FASTER THAN PREVIOUSLY THOUGHT...SO
INCREASED CLOUD COVER AS NEEDED THIS MORNING.

PREVIOUS DISCUSSION FOLLOWS...
HIGH PRESSURE WILL REMAIN ACROSS THE AREA TODAY...KEEPING THINGS DRY.

LARGE HOLES HAVE DEVELOPED IN THE CLOUD COVER THANKS TO SOME OF THE
DRIER AIR MOVING IN WITH THE HIGH. THE HOLES ROUGHLY FOLLOW THE
SURFACE RIDGE AXIS. MODELS SHOW SOME OF THIS DRY AIR PERSISTING
THROUGH THE DAY...BUT SOME OF THE HOLES ARE ALREADY CLOSING IN IOWA
AT THE MOMENT.

THUS SKY COVER FORECAST IS TOUGH TODAY AND CONFIDENCE IS LOW. KEPT
SKIES MOSTLY CLOUDY ACROSS THE NORTHEAST FORECAST AREA TODAY CLOSER
TO SOME COOLER AIR ALOFT WHICH WILL HELP KEEP THE CLOUDS THERE
INTACT. ACROSS THE SOUTHWEST HALF ALLOWED FOR SOME PARTLY CLOUDY
SKIES TODAY BASED ON LATEST TRENDS AND MODEL MOISTURE FORECASTS.

WHERE SKIES HAVE CLEARED...TEMPERATURES HAVE DIPPED TO AROUND 20
EARLY THIS MORNING. THE COLD START IN THESE AREAS...ALONG WITH
CLOUDS INHIBITING TEMPERATURE RISES ELSEWHERE...SHOULD LEAD TO HIGHS
A LITTLE COLDER THAN MAV MOS WOULD SUGGEST MOST AREAS.

&&

.SHORT TERM.../TONIGHT THROUGH SUNDAY NIGHT/
ISSUED AT 252 AM EST FRI DEC 19 2014

FOCUS IS ON ANY THREAT FOR PRECIPITATION AS WELL AS ON SKY COVER.
MODELS ARE CLOSE ENOUGH THAT A BLEND WAS USED.

AN UPPER TROUGH WILL MOVE ACROSS THE AREA LATER TONIGHT AND
SATURDAY. BULK OF FORCING AND MOISTURE WILL BE CONFINED WELL SOUTH
OF CENTRAL INDIANA. HIGH PRESSURE WILL REMAIN IN CONTROL AT THE
SURFACE.

THUS JUST EXPECT A THICKER CLOUD COVER TO MOVE IN ONCE AGAIN DURING
THIS PERIOD BUT NO MEASURABLE PRECIPITATION. CANNOT ABSOLUTELY RULE
OUT SOME FLURRIES SATURDAY...BUT AT THE MOMENT FEEL THAT THE ODDS
ARE TOO LOW TO MENTION.

SUNDAY AND SUNDAY NIGHT CENTRAL INDIANA WILL REMAIN IN BETWEEN
SYSTEMS TO THE NORTHWEST AND SOUTHEAST. SOME MODELS TRY TO BRING
SOME PRECIPITATION INTO THE FAR SOUTHEAST SUNDAY NIGHT...BUT DO NOT
FEEL THAT ODDS ARE GOOD ENOUGH TO WARRANT A MENTION YET.

THUS WILL JUST KEEP SKIES PARTLY TO MOSTLY CLOUDY THROUGH THE
PERIOD. NOT SURE THAT PARTLY CLOUDY CONDITIONS WILL REALLY
HAPPEN...BUT SOME HOLES COULD DEVELOP IN THE SKY COVER LIKE WHAT IS
HAPPENING AT THE MOMENT.

FOR TEMPERATURES...GENERALLY STAYED COOLER THAN MAV MOS FOR HIGHS
DUE TO EXPECTED CLOUD COVER. FOR LOWS STUCK WITH A BLEND.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 333 AM EST FRI DEC 19 2014

A MUCH MORE ACTIVE AND UNSETTLED WEATHER PATTERN SETTING UP FOR
THE HOLIDAY WEEK...HIGHLIGHTED BY A POTENTIAL LARGE STORM SET TO
IMPACT THE GREAT LAKES AND OHIO VALLEY TUESDAY THROUGH CHRISTMAS.
LOTS TO TALK ABOUT THIS MORNING.

STRONG RIDGING ALOFT SET TO DEVELOP OFF THE PACIFIC COAST AT THE
BEGINNING OF THE EXTENDED...AND THIS WILL PROMPT FALLING HEIGHTS
DOWNSTREAM EAST OF THE ROCKIES AS THE UPPER LEVEL FLOW AMPLIFIES.
QUITE A BIT OF ENERGY COURTESY OF A VERY STRONG UPPER LEVEL JET
PLOWING INTO THE PACIFIC NORTHWEST SET TO DIVE INTO THE EXPANDING
TROUGH AND LEAD TO PHASING WITH SOUTHERN STREAM JET ENERGY. AT THE
SURFACE...LOW PRESSURE SET TO TRACK OUT OF THE NORTHERN PLAINS ON
MONDAY WITH A TRAILING COLD FRONT. MOISTURE WILL BE DRAWN NORTH
INTO THE REGION AS THE FRONT AND SURFACE WAVE APPROACH...WITH RAIN
BECOMING LIKELY BY MONDAY NIGHT.

RAIN WILL CONTINUE ON TUESDAY AS THE AFOREMENTIONED SURFACE WAVE
TRACKS INTO THE GREAT LAKES. A SECOND AREA OF LOW PRESSURE SET TO
ORGANIZE OVER THE NORTHWEST GULF/LOWER MISSISSIPPI VALLEY DURING
THE DAY TUESDAY AS THE SUBTROPICAL JET ENERGY LINKS UP WITH THE
NORTHERN STREAM JET. THE UPPER TROUGH WILL QUICKLY GAIN A NEGATIVE
TILT WITH RAPID CYCLOGENESIS COMMENCING TUESDAY NIGHT INTO EARLY
WEDNESDAY.

INDIVIDUAL MODEL RUNS THIS MORNING DIFFER WITH REGARDS TO TIMING
AND LOCATION OF THE PHASING SURFACE WAVE...BUT THE KEY TAKEAWAY IS
THAT MODEL CONSENSUS INCLUDING BULK OF THE ENSEMBLE RUNS ALL SHOW
THE DEEPENING SYSTEM OVER THE EASTERN PART OF THE COUNTRY.
CONFIDENCE CONTINUES TO GROW IN A HIGH IMPACT SYSTEM FOR THE
REGION FROM LATE TUESDAY INTO EARLY THURSDAY...BUT THE DETAILS ARE
YET TO BE IRONED OUT AND LIKELY WILL NOT BE FOR ANOTHER FEW DAYS
UNTIL THE INTENSE UPPER JET ENERGY APPROACHING THE PACIFIC
NORTHWEST IS PROPERLY SAMPLED BY THE UPPER AIR NETWORK. AT THIS
POINT...HAVE LEANED IN THE DIRECTION OF THE GLOBAL MODELS WHICH
FAVOR A FASTER PHASING...BUT ALL POSSIBILITIES REMAIN OPEN AT THIS
EARLY STAGE UNTIL GREATER MODEL CONSENSUS CAN BE REACHED.

WITH ALL OF THIS BEING SAID...ANTICIPATE RAIN MIXING WITH THEN
CHANGING TO SNOW TUESDAY NIGHT INTO WEDNESDAY. FAR TOO EARLY TO
TALK POTENTIAL ACCUMULATIONS WEDNESDAY THROUGH EARLY THURSDAY...BUT
THESE LOOK RELATIVELY LIGHT AT THIS POINT. WIND IS LIKELY TO BE A
MORE SIGNIFICANT FACTOR CONSIDERING THE PROGGED INTENSITY OF THE
LOW TO SUB-980MB LEVELS AND POSSIBLY LOWER BY EARLY THURSDAY. EVEN
IF SNOW AMOUNTS ARE LIGHT...WIND DRIVEN SNOW SHOWERS COULD CREATE
TRAVEL DIFFICULTIES AT THE WORST POSSIBLE TIME...CHRISTMAS EVE
INTO EARLY CHRISTMAS MORNING. THOSE WITH TRAVEL PLANS DURING THIS
TIME PERIOD ARE ENCOURAGED TO STAY TUNED IN THE COMING DAYS. AND THIS
MAY JUST BE THE START...AS AN ACTIVE PATTERN LIKELY PERSISTS BEYOND
THE 7 DAY INTO NEXT WEEKEND.

&&

.AVIATION /DISCUSSION FOR 191200Z TAF ISSUANCE/...
ISSUED AT 537 AM EST FRI DEC 19 2014

MVFR CEILINGS POSSIBLE THROUGHOUT THE FORECAST PERIOD.

POCKET OF CLEAR SKIES EXTENDING SOUTHEAST FROM EXTREME EASTERN
IOWA INTO THE SOUTHERN HALF OF INDIANA EARLY THIS MORNING. STRATUS
LINGERS EITHER SIDE OF THIS AREA ACROSS THE REGION...AND REMAINS
THE PRIMARY CHALLENGE FOR THE FORECAST TODAY.

STRATUS ENCOMPASSING NORTHERN INDIANA HAS BEEN SLOWLY EXPANDING
SOUTH OVER THE LAST FEW HOURS...AND RAP/NAM 925MB ANALYSIS
SUGGESTS THIS TREND SHOULD CONTINUE THROUGH THE MORNING AIDED BY
WEAK NORTHEAST FLOW WITHIN THE BOUNDARY LAYER. IN ADDITION...MODEL
SOUNDINGS SHOW CONVECTIVE TEMPS ONLY AROUND 30F BY MIDDAY WITH
LIKELIHOOD THAT CU DEVELOPS AND COALESCES WITH THE STRATUS DECK.
WHILE THERE IS LIKELY TO BE PERIODS WITH SCATTERED CLOUD COVERAGE
THIS MORNING...OVERALL TREND SUPPORTS MORE OF A MOSTLY CLOUDY SKY
TODAY. BASES WILL LIKELY VARY ANYWHERE BETWEEN 2000-3500FT THROUGH
THE AFTERNOON.

HIGH PRESSURE REMAINS OVER THE AREA TONIGHT AS AN UPPER LEVEL WAVE
PASSES TO THE SOUTH. MODEL SOUNDINGS INDICATE CLOUDS ARE LIKELY TO
BE STUBBORN OVERNIGHT...WITH MOISTURE BECOMING TRAPPED ONCE AGAIN
UNDER AN INVERSION. WILL MAINTAIN MVFR CEILINGS AS A RESULT ALL
NIGHT. WINDS WILL BE LIGHT AND VARIABLE THROUGHOUT THE FORECAST
PERIOD.

&&

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

&&

$$

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

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