000
FXUS63 KIND 111849
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
249 PM EDT TUE MAR 11 2014

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

&&

.SYNOPSIS...
ISSUED AT 423 AM EDT TUE MAR 11 2014

A WARM SPRINGLIKE DAY WILL GIVE WAY TO A STRONG SYSTEM
THAT WILL BRING RAIN AND THEN SNOW TO THE AREA TONIGHT AND
WEDNESDAY. STRONG WINDS WITH THE SYSTEM WILL BE IN PLACE ON
WEDNESDAY AS WELL. QUIET WEATHER WITH THE EXCEPTION OF SLIGHT RAIN
CHANCES FRIDAY NIGHT UNTIL SUNDAY WHEN ANOTHER STORM SYSTEM ARRIVES
BRINGING CHANCES FOR MIXED PRECIPITATION THROUGH MONDAY.

&&

.NEAR TERM /TODAY/...

ISSUED AT 423 AM EDT TUE MAR 11 2014

QUIET DAY BEFORE THE STORM ARRIVES UNDER WARM ADVECTION. SHOULD SEE
SOME CLOUDS FROM ADVECTION BUT THESE WILL DO LITTLE TO LIMIT WARMING
AS 850 MB TEMPERATURES CLIMB TO AROUND 10C. LOOK FOR HIGHS IN THE
60S TO AROUND 70.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...

ISSUED AT 423 AM EDT TUE MAR 11 2014

FORECAST FOCUS IS ON STORM SYSTEM TONIGHT THROUGH WEDNESDAY. NAM IS
A NORTHERN OUTLIER WITH THE LOW TRACK SO GENERALLY DISREGARDED IT.
FAIRLY SIMILAR FEATURES SEEN IN GFS AND 12Z ECMWF SO GENERALLY
AVERAGED THEM...BUT DISCUSSION WILL FOCUS ON SPECIFICS SEEN IN THE
GFS.

AT 6Z GFS SHOWS STRONG FRONTOGENESIS ACROSS THE CENTRAL AND SOUTHERN
COUNTIES WITH TEMPERATURE PROFILES WELL ABOVE FREEZING AND A
SOUTHWESTERLY LLJET OF AROUND 50 KTS. DECENT ISENTROPIC LIFT FROM 0
TO 6Z WITH THIS FEATURE. WITH ELEVATED INSTABILITY AVAILABLE
CONTINUED WITH MENTION OF SLIGHT CHANCE FOR THUNDER.

850-700 LAYER FRONTOGENESIS IS PHENOMENAL ACROSS THE NORTHERN HALF
OR SO OF THE AREA AT 12Z ACCORDING TO THE GFS /OVER 50 AND OVER 100
OVER THE FAR NORTHERN COUNTIES/. Q VECTOR CONVERGENCE ALOFT OVER 30
FOR THE ENTIRE AREA AND OVER 50 ACROSS THE NORTHERN HALF OR SO. OF
NOTE IN THE CROSS SECTION THOUGH IS THAT THE AREA OF NEGATIVE EPV
/ENHANCED INSTABILITY/ IS SHOWING UP JUST BELOW A DECENT INTRUSION
OF DRY AIR ALOFT WHICH COULD BE FALSELY ENHANCING THE POTENTIAL
INSTABILITY. DRY AIR RUSHING IN ALOFT COULD ALSO CUT DOWN ON
DENDRITIC GROWTH THEREBY CUTTING DOWN ON SNOW AMOUNTS.

SHORTWAVE SHOWING UP AS PRESSURE ADVECTION ON A PV SURFACE MOVES
THROUGH BETWEEN 12 AND 18Z WEDS. AT THIS POINT LOOKS LIKE SYSTEM
WILL BE ZIPPING THROUGH THE AREA AND MAJORITY OF PRECIP COULD BE
COMING TO AN END ACROSS MUCH OF THE AREA BY AROUND 18Z.

AS FAR AS PRECIPITATION TYPE IS CONCERNED...FORECAST SOUNDINGS SHOW
THERMAL PROFILES OF ALL RAIN ACROSS THE ENTIRE AREA THROUGH 6Z.
BETWEEN 6Z AND 9Z COLDER AIR STARTS TO MOVE IN FROM THE
NORTHWEST...BUT LOOKS LIKE A SHORT-LIVED WARM LAYER REMAINS ALOFT
WHICH COULD ALLOW FOR SOME BRIEF SLEET BEFORE CHANGING OVER TO SNOW.
BY 15Z SOUNDINGS SHOW ALL SNOW EVEN SOUTH OF THE AREA SO HAVE THE
ENTIRE AREA SNOW STARTING THEN. IN BETWEEN 9 AND 15Z SHOULD SEE SNOW
MOVE IN FROM THE NORTHWEST AND SEE A SIMILAR TRANSITION FROM
NORTHWEST TO SOUTHEAST OF RAIN TO A MIX OF RAIN/BRIEF SLEET/SNOW TO
SNOW.

AS FAR AS SNOW AMOUNTS ARE CONCERNED...LOOKS LIKE THE NORTHERN
COUNTIES COULD SEE 3-5 INCHES...WITH AROUND 2 OR SO CENTRAL AND
TRACE TO 1 IN THE SOUTH. WITH THE STRONG FORCING IN THE NORTH
COULDN/T RULE OUT 6 INCHES SOMEWHERE...BUT WITH THE WARM GROUND TO
START OUT AND THE DRY AIR MOVING IN QUICKLY ALOFT TO SHUT THINGS
DON/T EXPECT TO SEE THAT WIDESPREAD EVEN IN THE NORTHERN COUNTIES.
WENT WITH A WINTER WEATHER ADVISORY FOR THE NORTHERN COUNTIES WITH
THE ANTICIPATED SNOW AMOUNTS.

ANOTHER BIG CONCERN WILL BE THE WIND WITH THIS SYSTEM. A TIGHT
PRESSURE GRADIENT DEVELOPS ACROSS THE AREA AS THE LOW MOVES THROUGH.
COULD SEE WIND GUSTS AROUND 40 MPH. COMBINING THESE WITH ANY SNOW
COULD LEAD TO SOME PRETTY SERIOUS VISIBILITY ISSUES...ESPECIALLY IN
THE NORTHERN COUNTIES WHICH COULD SEE A PERIOD OF MODERATE TO HEAVY
SNOW. FOR NOW WILL KEEP THE WINTER WEATHER ADVISORY CONFINED TO THE
NORTHERN COUNTIES WITH THE HEAVIEST SNOW BUT COULD SEE THE POTENTIAL
FOR EXPANDING IT SOUTHWARD IF CHANGEOVER TO ALL SNOW OCCURS FASTER
THAN CURRENTLY FORECAST.

HIGH PRESSURE BUILDS IN WEDNESDAY NIGHT AND DRY THEN THROUGH
THURSDAY NIGHT WITH TEMPERATURES REMAINING BELOW NORMAL.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 249 PM EDT TUE MAR 11 2014

ROLLER COASTER RIDE CONTINUES THROUGH THE EXTENDED AS THE UPPER
LEVEL PATTERN TRANSITIONS FROM A QUASI ZONAL FLOW TO A MUCH MORE
AMPLIFIED PATTERN WITH RIDGING IN THE WEST AND AN UPPER TROUGH
SETTING UP OVER THE GREAT LAKES BY EARLY NEXT WEEK.

STRONG SOUTHWEST FLOW WILL BRING MILDER TEMPERATURES BACK INTO THE
OHIO VALLEY ON FRIDAY AHEAD OF A WEAK COLD FRONT. THE FRONT WILL
SWING ACROSS THE FORECAST AREA FRIDAY NIGHT AND EARLY SATURDAY
BRINGING LIGHT RAIN. WEAK HIGH PRESSURE BUILDS IN FOR SATURDAY WITH
DRY WEATHER AND SEASONABLE TEMPS. THE EXPANSION OF A STRONG CANADIAN
HIGH PRESSURE AND THE AFOREMENTIONED TROUGH ALOFT WILL PROMOTE
COOLER TEMPERATURES FOR SUNDAY AND MONDAY...ALONG WITH ADDITIONAL
CHANCES FOR PRECIP AS A STRONGER AREA OF LOW PRESSURE PASSES TO THE
SOUTH OF THE REGION THROUGH THE SOUTHEAST STATES. EXPECT HIGH TEMPS
TO FALL BACK INTO THE 30S AND LOWER 40S MONDAY WITH A RECOVERY TO
NEAR NORMAL TEMPS TUESDAY.

&&

.AVIATION /DISCUSSION FOR 111800Z TAF ISSUANCE/...
ISSUED AT 139 PM EDT TUE MAR 11 2014

VFR CONDITIONS THROUGH MID EVENING...THEN RAPIDLY DETERIORATING
CONDITIONS THEREAFTER AS STRONG LOW PRESSURE TRACKS INTO THE
REGION.

HIGH PRESSURE CURRENTLY ACROSS THE OHIO VALLEY EARLY THIS
AFTERNOON WILL GIVE WAY TO STRONG LOW PRESSURE DEVELOPING OVER THE
CENTRAL PLAINS. THE LOW WILL STRENGTHEN AS IT TRACKS NORTHEAST
ALONG A SLOWLY SOUTHWARD MOVING FRONT...PROGRESSING INTO THE OHIO
VALLEY AFTER MIDNIGHT. CEILINGS WILL FALL QUICKLY TO MVFR LEVELS
BY LATE EVENING WITH THE ONSET OF WIDESPREAD RAINFALL. AXIS OF
ELEVATED INSTABILITY WILL DEVELOP ALONG THE FRONTAL BOUNDARY
OVERNIGHT AND COMBINED WITH FORCING ALOFT...PRODUCE EMBEDDED
CONVECTION AND THE POTENTIAL FOR THUNDER TO IMPACT ALL TERMINALS.

AS THE LOW PASSES JUST SOUTH OF THE TERMINALS LATE TONIGHT...MUCH
COLDER AIR WILL BE DRAWN QUICKLY INTO THE REGION ON THE BACK SIDE
OF THE SYSTEM. MODEL SOUNDING AND CRITICAL THICKNESSES ANALYSIS
SUGGESTING RAIN CHANGING OVER TO SNOW BY 08-09Z AT KLAF...AND 12-13Z
FOR THE OTHER THREE SITES. COULD SEE A BRIEF PERIOD WITH SLEET
BECOMING PREDOMINANT AS THE BOUNDARY LAYER COOLS...BUT LEFT OUT
MENTION IN FORECASTS AS ANY MIXING EXPECTED TO BE GENERALLY AN
HOUR OR LESS BEFORE SNOW BECOMES THE MAIN PRECIP TYPE. BESIDES
THE IMPACTS OF HEAVY PRECIP RATES...EXTREMELY TIGHT PRESSURE
GRADIENT DEVELOPING AS THE LOW PASSES WILL PROMOTE NORTHERLY
SUSTAINEDS INCREASING TO NEAR 30KTS WITH GUSTS AT 40KTS BEGINNING
JUST BEFORE DAYBREAK AND PERSISTING THROUGH THE MORNING. DEPENDING
ON HOW FAST SNOW AND TEMPS FALL...BLOWING SNOW MAY BECOME A FACTOR
WEDNESDAY MORNING AS WELL. SNOWFALL RATES WILL DIMINISH BY MIDDAY
AS THE SYSTEM PULLS AWAY TO THE EAST. WIND GUSTS WILL REMAIN IN
EXCESS OF 35KTS THROUGH THE END OF THE FORECAST PERIOD.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM EDT WEDNESDAY FOR
INZ021-028>031-035-038-040>042.

&&

$$

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

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