Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 040431
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1231 AM EDT WED MAY 4 2016

.SYNOPSIS...
ISSUED AT 340 PM EDT TUE MAY 3 2016

RAIN WILL RETURN TO THE AREA LATE TONIGHT AS ANOTHER COLD FRONT
SWEEPS THROUGH THE REGION. SHOWERS WILL THEN CONTINUE THROUGH
THURSDAY MORNING ALONG WITH COOL AND BREEZY CONDITIONS. HIGH
PRESSURE BRINGS WARMER AND DRIER CONDITIONS ON FRIDAY BUT ANOTHER
FRONT WILL ARRIVE ON SATURDAY WITH ANOTHER CHANCE OF RAIN.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 340 PM EDT TUE MAY 3 2016

STRONG (120+ KT) MERIDIONAL UPPER JET IS CURRENTLY DIGGING INTO
THE UPPER MIDWEST AND CARVING OUT A HEALTHY PV ANOMALY ON THE
CYCLONICALLY SHEARED SIDE THAT WILL IMPACT OUR WEATHER DURING THE
NEXT 12-48 HOURS. MAIN LOW LEVEL CONVERGENCE/FGEN BOUNDARY...AND
BEST CHANCES OF RAIN...WILL ARRIVE LATE TONIGHT INTO TOMORROW
MORNING. A FEW SCATTERED SHOWERS REMAIN POSSIBLE IN WAA REGIME
AHEAD OF THE WAVE BUT BY FAR BEST RAIN CHANCES WILL BE AFTER 06Z.
FORCING FOR ASCENT IS SUPERB WITH STRONG MIDLEVEL HEIGHT FALLS/CVA
AND A HEALTHY DEFORMATION BAND IN LEFT EXIT REGION OF UPPER JET
SUPPORTING A DEEP AND WELL-DEFINED FRONTAL CIRCULATION. SUFFICIENT
DEEP-LAYER MOISTURE ADVECTION WILL ALSO LEAD TO A RESPECTABLE
0.8-0.9 INCHES OF PW AND...MORE IMPORTANTLY...MAINTAIN AT LEAST
NEUTRAL STATIC STABILITY. COMBINATION OF THESE FACTORS SHOULD
SUPPORT WIDESPREAD RAIN WITH 0.25-0.5 INCHES BY MIDDAY TOMORROW.
NOT IMPRESSED WITH THUNDER CHANCES THOUGH GIVEN MOIST ADIABATIC
LAPSE RATES THROUGH THE COLUMN. CHANCES FOR CONVECTION A LITTLE
BETTER EAST OF I-69 AROUND MIDDAY AS MIDLEVEL COLD POOL SETTLES
OVERHEAD AND COULD SEE SOME MARGINAL SURFACE HEATING BEFORE COLD
FRONT ARRIVES. TIME WINDOW IS HIGHLY LIMITED THOUGH. LATEST GFS
INDICATES VIRTUALLY NO SURFACE-BASED INSTABILITY AND ONLY A FEW
HUNDRED J/KG OF 0-1KM MLCAPE ON MORE AGGRESSIVE 12Z NAM12.
MAINTAINED INHERITED SLIGHT CHANCE MENTION WITH PASSING FRONT BUT
SUSPECT ANY THUNDER WILL BE VERY ISOLATED AND NOTHING
STRONG/SEVERE ANTICIPATED. WEDNESDAY WILL ACTUALLY BE A FAIRLY RAW
DAY FOR MOST LOCATIONS WITH N/NW WINDS GUSTING TO NEAR
30MPH...TEMPS AROUND 50F...AND LINGERING CLOUDS/PRECIP.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 PM EDT TUE MAY 3 2016

SLIGHT IMPROVEMENT THURSDAY BUT MIDLEVEL DEFORMATION WILL MAINTAIN A
CHANCE OF SHOWERS...ESPECIALLY IN OUR EASTERN COUNTIES. EXPANDED WED
NIGHT POPS WESTWARD BASED ON LATEST GUIDANCE SHOWING MOISTURE PLUME
GETTING THROWN BACK TO OUR WESTERN COUNTIES. PRIMARILY DRY
CONDITIONS THEN EXPECTED EVERYWHERE BY LATE THURSDAY INTO EARLY
SATURDAY AS MIDLEVEL RIDGE FOLDS SOUTHEAST. GFS AND ECMWF TRYING
TO GENERATE SOME SPURIOUS QPF FRIDAY EVENING ALONG LEADING EDGE OF
THETA-E RETURN. SYNOPTIC PICTURE DOES NOT BODE WELL FOR PRECIP
CHANCES IN GENERALLY DRY AND WEAKLY SUBSIDENT REGIME. MAINTAINED
DRY POPS BUT SUPPOSE A STRAY SHOWER MAY BE POSSIBLE IN OUR WESTERN
COUNTIES. MORE NOTABLE ASPECT OF FRIDAY FORECAST WILL BE
TREMENDOUS THERMAL RECOVERY. WAA AND AT LEAST PARTLY SUNNY SKIES
SHOULD PUSH HIGHS INTO THE UPPER 60S/LOW 70S...ROUGHLY 30 DEGREE
DIURNAL RANGE. COULD EASILY SEE SOME OVER ACHIEVEMENT OF HIGH
TEMPS IF FULL SUN MATERIALIZES...PUSHING MID 70S PER MEX GUIDANCE.
WILL MAINTAIN A MORE CONSERVATIVE APPROACH FOR NOW THOUGH WITH
SOME QUESTION AS TO AFTERNOON CLOUD COVER.

NEXT SHORTWAVE/COLD FRONT WILL ARRIVE LATE SATURDAY. LATEST MODELS
IN A LITTLE BETTER AGREEMENT ON TIMING/EVOLUTION BUT CONFIDENCE IS
STILL LOW AT THIS TIME RANGE. BEST CHANCES FOR RAIN CURRENTLY
APPEAR TO BE LATE SATURDAY WITH DRY/COOL CONDITIONS FOR SUNDAY AS
FRONT SETTLES JUST SOUTH OF OUR AREA. THIS FRONT WILL STALL ACROSS
THE REGION AND RETURN NORTH EARLY NEXT WEEK AS A LARGE CUTOFF LOW
LIFTS OUT OF THE SOUTHWEST CONUS. AGAIN...LATEST MODELS IN GENERAL
AGREEMENT ON THIS BUT WOULD LIKE TO SEE SOME CONTINUITY BEFORE
JUMPING FULLY ON BOARD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1230 AM EDT WED MAY 4 2016

AN UPPER LEVEL TROF WILL MOVE SOUTH ACROSS THE MIDWEST TODAY.
AHEAD OF THIS SYSTEM...A COLD FRONT WILL MOVE ACROSS NORTHERN
INDIANA AND BE ACCOMPANIED BAY SHOWERS AND LOWER CEILINGS. AT
04Z...A CLUSTER OF THUNDERSTORMS WAS OVER FAR SW WI AND EXTREME NE
IA. THE STORMS WERE JUST ENTERING NW IL. THE LATEST NAM AND ARW
BUFKIT FORECAST SOUNDINGS OVER NRN INDIANA LIMIT MID LEVEL
INSTABILITY TO 50 J/KG. SPC MOST UNSTABLE CAPES WERE VIRTUALLY
ZERO OVER THE ENTIRE REGION...SO EXPECT THE STORMS WILL PASS BY TO
THE WEST OF THE TERMINALS WHERE THE BEST UPPER LEVEL SUPPORT WILL
REMAIN.

MADE SOME MINOR CHANGES TO THE ONGOING TAFS IN REGARD TO THE
TIMING OF THE FRONT AND SUBSEQUENT ARRIVAL OF LOW CLOUDS. AN
UPPER LEVEL LOW WILL DRIFT SOUTH OVER THE AREA LATER TODAY BEHIND
THE FRONT AND SHOULD KEEP CONDITIONS FROM BECOMING VFR. TAFS MAY
BE TOO OPTIMISTIC WITH MVFR CONDITIONS LATE IN THE TAF PERIOD.
GUT FEELING WITH THE UPPER LEVEL LOW AND RESIDUAL MOISTURE OVER
THE AREA...CONDITIONS MAY BECOME IFR LATE IN THE TAF PERIOD.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 5 AM TO 5 PM EDT THURSDAY FOR LMZ043-
     046.

     GALE WARNING FROM 6 AM THIS MORNING TO 5 AM EDT THURSDAY FOR
     LMZ043-046.

&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...SKIPPER


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