Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 300520
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
120 AM EDT SAT MAY 30 2015

.SYNOPSIS...
ISSUED AT 528 PM EDT FRI MAY 29 2015

THERE IS A CHANCE FOR SOME RAIN TONIGHT AHEAD OF AN APPROACHING COLD
FRONT. LOW TEMPERATURES TONIGHT WILL BE IN THE UPPER 60S. SHOWER
AND THUNDERSTORM CHANCES INCREASE TOMORROW AS THE COLD FRONT MOVES
THROUGH THE REGION. HIGH TEMPERATURES TOMORROW WILL RANGE FROM
THE LOWER 60S NEAR LAKE MICHIGAN TO THE LOWER 80S IN SOUTHEASTERN
INDIANA.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 341 PM EDT FRI MAY 29 2015

NEARLY 1000 J/KG OF MLCAPE IN AN UNCAPPED WARM SECTOR WILL CONTINUE
TO SUPPORT ISOLATED SHOWERS (MAYBE A RUMBLE OF THUNDER) THROUGH
THE MID-LATE AFTERNOON HOURS AS REMNANT OUTFLOW ATTACHED TO
SHORTWAVE LIFTING NE INTO THE WESTERN LAKES SETTLES IN. LOSS OF
DIURNAL HEATING AND LITTLE MID/UPPER LEVEL SUPPORT SHOULD RESULT IN
A MILD/MAINLY DRY PERIOD TONIGHT. WITH THAT SAID RAMP UP OF LOW
LEVEL JET (LINGERING ELEVATED INSTABILITY) IN ADVANCE OF THIS
UPSTREAM FEATURE...AND POTENTIAL FOR CONVECTIVELY INDUCED/AIDED
VORTS TO LIFT THROUGH IN MOIST SW FLOW SUGGEST MAINTAINING AT LEAST
LOW CHC POPS FOR SHOWERS (HIGHEST WEST) THE WAY TO GO.

ON SATURDAY...LARGE SCALE ASCENT INCREASES WITH TIME AS VIGOROUS
NORTHERN STREAM PV ANOMALY DROPPING SE THROUGH ONTARIO PARTIALLY
PHASES WITH A SHEARING SHORTWAVE THAT WILL BE WORKING TOWARD THE
MID MS VALLEY. THERE WILL ALSO BE SEPARATE CONVECTIVELY AIDED VORT
THAT WILL BE IN THE ACT OF LIFTING INTO THE WESTERN OH VALLEY BY
LATER IN THE DAY. IN THE LOW LEVELS...A BAROCLINIC ZONE WILL
GRADUALLY SHIFT SE THROUGH WESTERN/NORTHERN ZONES MORNING/EARLY
AFTERNOON AND POINTS SE DURING THE AFTERNOON. THE FGEN/DEFORMATION
RESPONSE UNDER THE RRQ OF A STRENGTHENING UPPER JET OFF TO THE
NORTHEAST APPEARS IMPRESSIVE BY SATURDAY AFTERNOON/EVENING....WITH
WHEN COMBINED WITH MORE THAN AMPLE MOISTURE (850 MB MIXING RATIOS
PUSHING 10-11C) SHOULD BE ENOUGH TO PROVIDE THE ENTIRE AREA WITH A
DECENT RAIN EVENT (ESPECIALLY LATER SATURDAY AFTN-EVE). THERE ALSO
REMAINS A VERY LOW CHANCE FOR STRONG-SEVERE MULTICELLS IN THE
AFTERNOON ACROSS SOUTHERN/EASTERN ZONES IF ENOUGH HEATING OCCURS
WITH STRONGER FLOW/SHEAR EXPECTED TO LAG JUST BEHIND THE SFC
FRONT.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 341 PM EDT FRI MAY 29 2015

RAIN SHOWERS...WITH PERHAPS SOME EMBEDDED THUNDER EXPECTED TO
CONTINUE INTO SATURDAY EVENING AS UPSTREAM TROUGH CURRENTLY ACROSS
NEBRASKA PANHANDLE REGION APPROACHES THE REGION. A RATHER IMPRESSIVE
WATER VAPOR PRESENTATION OF THIS WAVE NOTED THIS AFTERNOON ACROSS
THE CENTRAL PLAINS...AND LAST FEW RUNS OF BULK OF GUIDANCE HAVE
TRENDED TOWARD A SLIGHTLY SLOWER AND MORE AMPLIFIED SOLUTION
CONCERNING THIS WAVE. SMALL DIFFERENCES IN THE NATURE OF THIS WAVE
WILL HAVE A BIG IMPACT ON LOW LEVEL BAROCLINIC ZONE PLACEMENT AND
LONGEVITY OF RAIN ACROSS THE AREA INTO SUNDAY MORNING. GIVEN CURRENT
OBSERVATIONAL TRENDS AND MAJORITY OF DPROG/DT DATA...HAVE GENERALLY
BOUGHT IN ON A MORE AMPLIFIED SOLUTION AND HAVE INCREASED POPS FOR
THE SATURDAY EVENING PERIOD AS LOW/MID LEVEL FGEN FORCING PERSISTS
ACROSS THE AREA IN ADVANCE OF THIS WAVE. ANAFRONT CHARACTERISTICS OF
THIS BAROCLINIC ZONE WILL ALSO SUPPORT GOOD DEAL OF ELEVATED
MOISTURE BEHIND THE SURFACE COLD FRONT WITH NAM KEEPING UPWARDS OF
1.5 INCH PWATS EVEN ACROSS NORTHERN PORTIONS OF CWA LATE IN THE
EVENING. SOME ISOLATED THUNDER MAY PERSIST INTO SATURDAY EVENING
ESPECIALLY FOR SOUTHEAST HALF OF THE AREA...BUT STORM TOTAL RAINFALL
AMOUNTS WILL LIKELY BE THE PRIMARY CONCERN THROUGH SATURDAY EVENING
WITH AMOUNTS IN EXCESS OF AN INCH POSSIBLE FOR SOUTHEAST TWO THIRDS.

CONFIDENCE DIMINISHES FURTHER IN REGARDS TO POPS FOR LATE SATURDAY
NIGHT INTO EARLY SUNDAY WITH 12Z EC/NAM STILL DEPICTING STRONGER
SOUTHERN STREAM SHORT WAVE LIFTING OUT OF THE SOUTHERN PLAINS THAT
MAY INTERACT WITH THE STRONG LOW/MID LEVEL THETAE GRADIENT. HAVE
MAINTAINED SHARP NORTHWEST TO SOUTHEAST POP GRADIENT FOR
SUNDAY...WITH HIGHEST CHANCE POPS ACROSS THE SOUTHEAST. THIS PERIOD
WILL LIKELY NEED FURTHER POP ADJUSTMENT OVER THE NEXT FEW FORECAST
CYCLES ONCE CONFIDENCE INCREASES REGARDING NATURE OF THIS SOUTHERN
STREAM WAVE AND SHEARED VORTICITY MAX LIFTING INTO THE OHIO VALLEY.

OTHERWISE...MUCH COOLER CONDITIONS IN STORE FOR SUNDAY AND HAVE
CONTINUED TREND OF PREVIOUS FORECAST IN A SLIGHT SLOWING OF
MODERATING TEMPERATURE TREND AS MORE PRONOUNCED NORTHERN STREAM
TROUGH HELPS REINFORCE GREAT LAKES THERMAL TROUGH. UPPER RIDGING TO
BUILD ACROSS THE AREA TOWARD MIDWEEK RESULTING IN A SHARPER WARMING
TREND...WITH TEMPS UP NEAR 80 AGAIN BY WEDNESDAY. PRECIP CHANCES
LOOK MINIMAL AT LEAST UNTIL FRIDAY AS MID/UPPER LEVEL RIDGING
PERSISTS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 103 AM EDT SAT MAY 30 2015

SHRA/TS EXPECTED TO INCREASE IN COVERAGE FROM NW-SE ACROSS THE
AREA TODAY AS A CDFNT MOVES SE INTO NRN INDIANA. CONDITIONS
SHOULD GENERALLY LOWER TO MVFR IN THE SHRA BY THIS AFTN. AMOUNT OF
DESTABILIZATION AND SUBSEQUENT TS COVERAGE QUESTIONABLE SO JUST
CONTD WITH VCTS IN TAFS FOR TODAY. POST FRONTAL RAIN EXPECTED
TONIGHT AS A WAVE MOVES NE ALONG THE FRONT RESULTING IN IFR
CONDITIONS.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 5 PM EDT SUNDAY
     FOR LMZ043-046.

&&

$$

SYNOPSIS...LOTHAMER
SHORT TERM...STEINWEDEL
LONG TERM...MARSILI
AVIATION...JT


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