Area Forecast Discussion
Issued by NWS Northern Indiana

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105
FXUS63 KIWX 031725
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
125 PM EDT TUE MAY 3 2016

.SYNOPSIS...
ISSUED AT 108 PM EDT TUE MAY 3 2016

A BRIEF PERIOD OF DRY WEATHER IS EXPECTED INTO THIS EVENING BUT
RAIN CHANCES WILL QUICKLY RETURN OVERNIGHT. LOW TEMPERATURES WILL
BE IN THE MIDDLE TO UPPER 40S. RAIN IS EXPECTED ON WEDNESDAY AND
AN ISOLATED THUNDERSTORM IS ALSO POSSIBLE. IT WILL BE A COLD AND
BLUSTERY DAY FOR EARLY MAY. HIGH TEMPERATURES ARE ONLY EXPECTED TO
REACH THE LOWER TI MID 50S WITH WINDS BECOMING NORTHWEST AT 20 TO
30 MPH. IT WILL BE EVEN COLDER NEAR LAKE MICHIGAN. A CHANCE FOR
SHOWERS WILL PERSIST INTO THURSDAY BEFORE CONDITIONS BEGIN TO DRY
OUT AND WARM UP ACROSS THE REGION.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 408 AM EDT TUE MAY 3 2016

LINGERING PESKY LIGHT SHOWERS/PATCHY DRIZZLE TODAY AND NEXT
LIKELIHOOD OF RAIN LATE TONIGHT/WEDNESDAY WILL CONTINUE TO BE THE
PRIMARY CONCERNS FOR THE SHORT TERM PERIOD.

SHOWERS HAVE INCREASED IN COVERAGE OVER THE PAST FEW HOURS ACROSS
CENTRAL/SOUTH CENTRAL PORTIONS OF THE FORECAST AREA. PERTURBED
MID/UPPER LEVEL FLOW CONTINUES THIS MORNING WITH NEXT SHORT WAVE
APPROACHING FROM THE MID MS VALLEY. INVERTED LOW LEVEL TROUGH
APPEARS TO HAVE ALLOWED NARROW CORRIDOR OF SLIGHTLY BETTER
MOISTURE TO REMAIN ANCHORED ACROSS THESE LOCATIONS. MOIST LOW
LEVELS MAY BE ALLOWING FOR SOME VERY WEAK SFC/NEAR SFC INSTABILITY
AUGMENTING THESE SHOWERS ALSO...ALTHOUGH AMDAR SOUNDINGS ARE
SUPPORTIVE OF NEAR TERM BUFFER SOUNDINGS IN DEPICTING A FAIRLY
SHARP LOW LEVEL INVERSION BASED JUST ABOVE 800 HPA. SCATTERED
LIGHT SHOWERS/PATCHY DRIZZLE LIKELY TO CONTINUE THROUGH THROUGH
THE MORNING WITH EXPECTATION THAT AXIS MAY SLOWLY SHIFT
SOUTHEASTWARD WITH PROGRESSION OF ABOVE FEATURES THROUGH MIDDAY.
IN TERMS OF SKY COVER...NORTHERN EDGE OF LOW CLOUDS ACROSS
SOUTHERN LOWER MICHIGAN HAD BEEN EXHIBITING SOME SOUTHWARD
PROGRESSION...BUT RECENT TRENDS APPEAR TO HAVE SLOWED THIS
SOUTHWARD CLEARING WITH APPROACH OF THE UPPER SHORT WAVE. LOW
LEVEL WINDS SHOULD BEGIN TO BACK MORE NORTHERLY AS THIS FEATURE
TRACKS ACROSS THE SOUTHERN GREAT LAKES THIS MORNING EVENTUALLY
ALLOWING DRIER LOW LEVEL AIR TO ADVECT SOUTHWARD RESULTING IN
NORTH TO SOUTH DIMINISHING CLOUD TREND IN THE AFTERNOON.
MODERATION OF LOW LEVEL THERMAL TROUGH AND DIMINISHING
CLOUDS/RISING CEILINGS TODAY SHOULD SUPPORT HIGHS IN THE 60 TO 65
DEGREE RANGE.

FOCUS FOR TONIGHT WILL THEN SHIFT UPSTREAM TO A MORE VIGOROUS UPPER
LEVEL SHORT WAVE DIGGING ACROSS THE GREAT LAKES. AXIS OF INCREASING
WESTERLY FLOW WILL LIKELY LEAD TO A RELATIVELY NARROW CORRIDOR OF
STRONGER ISENTROPIC UPGLIDE ACROSS ESPECIALLY NORTHERN/NORTHWEST
PORTIONS OF THE AREA THIS EVENING. SUBCLOUD MOISTURE WILL INITIALLY
BE LACKING BUT ENOUGH ELEVATED MOISTURE ADVECTION MAY SUPPORT SOME
SCATTERED SHOWERS ACROSS THESE LOCATIONS THIS EVENING. RAIN WILL
BECOME LIKELY OVERNIGHT INTO WEDNESDAY MORNING FROM WEST TO EAST AS
LARGE SCALE FORCING INCREASES WITH THIS TROUGH WITH ACCOMPANYING
STRONG FRONTAL CONVERGENCE. WHILE INSTABILITY MAGNITUDES STILL
APPEAR MARGINAL...OVERALL IMPRESSIVE DYNAMICS AND WEAK ELEVATED
INSTABILITY AIDED BY 7-8 DEG C/KM MID LEVEL LAPSE RATES SHOULD
SUPPORT SOME ISOLD/SCATTERED THUNDER FOR OVERNIGHT INTO WEDNESDAY.
WILL MAINTAIN LIKELY POPS FOR GREATEST DURATION ACROSS THE EAST DUE
TO DIGGING NATURE OF TROUGH AND SOME DEFORMATION FORCING NORTH OF
THE MID/UPPER LEVEL HEIGHT MINIMUM WEDNESDAY/WEDNESDAY NIGHT.
CONFIDENCE IN POPS IS SOMEWHAT LOW ACROSS WESTERN TWO THIRDS OF THE
FORECAST AREA LATER WEDNESDAY INTO WEDNESDAY NIGHT WITH AT LEAST A
POSSIBILITY THAT VORT LOBE ROTATING THROUGH BASE OF THIS TROUGH TO
THE SOUTH MAY ALLOW FOR LOW LEVEL MOISTURE TO WRAP BACK WESTWARD
WITH SOME ADDITIONAL LIGHT RAIN. BREEZY/WINDY CONDITIONS TO DEVELOP
ACROSS ESPECIALLY WESTERN PORTIONS OF THE FORECAST AREA WEDNESDAY
WITH SOME NORTH GUSTS OVER 30-35 MPH POSSIBLE IN THE AFTERNOON.
COOLER CONDITIONS FOR WEDNESDAY NIGHT AS LOW LEVEL THERMAL TROUGH
OVERSPREADS THE AREA WITH LOWS AROUND 40.

&&

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 408 AM EDT TUE MAY 3 2016

FOR THURSDAY...SOME LINGERING LIGHT RAIN IS POSSIBLE ACROSS THE EAST
BUT DEPARTURE OF UPPER NEGATIVE HEIGHT ANOMALY AND ONSET OF MID LEVEL
HEIGHT RISES SHOULD RESULT IN DRYING CONDITIONS FOR THE AFTERNOON.
LARGE AMPLITUDE OF PATTERN WILL RESULT IN ONLY SLIGHT
PROGRESSION/MODERATION OF LOW LEVEL THERMAL TROUGHING ACROSS THE
AREA WITH HIGHS GENERALLY FROM THE MID 50S TO AROUND 60. MORE
SUBSTANTIAL WARMING EXPECTED BY FRIDAY AS STRONG LOW LEVEL THERMAL
RIDGING FROM THE CENTRAL/NORTHERN PLAINS SHIFTS EASTWARD IN ADVANCE
OF ANOTHER ROBUST SOUTH CENTRAL CANADIAN TROUGH.

WHILE MEDIUM RANGE MODELS CONTINUE TO SUPPORT IDEA LOCAL AREA
SHOULD ONLY BE GRAZED BY STRONGER FORCING WITH THIS TROUGH...WILL
MAINTAIN CHANCE POPS FOR SATURDAY/SATURDAY NIGHT. A BIG ITEM OF
UNCERTAINTY AT THIS FORECAST DISTANCE OUTSIDE OF FRONTAL TIMING IS
THE QUALITY OF MOISTURE RETURN PRECEDING THE FRONT. BETTER
MOISTURE ADVECTION MAY CIRCUMNAVIGATE THE AREA INTO THE CENTRAL
PLAINS/UPPER MIDWEST WITH A POSSIBILITY OF A NARROW AXIS OF POOLED
MOISTURE ACCOMPANYING THE FRONT. CONFIDENCE IN POPS FURTHER
DIMINISHES ON SUNDAY WITH EVEN WEAKER FORCING...BUT WITH PATTERN
SUPPORTING AT LEAST EVENTUAL RETURN FLOW OVER THIS BOUNDARY EARLY
NEXT WEEK...HAD TO MAINTAIN BROADBRUSH NATURE TO CHANCE POPS
THROUGH THIS PERIOD. IN TERMS OF TEMPS...HIGHS SHOULD REACH THE 70
DEGREE MARK FOR MANY LOCATIONS FRIDAY AND MAY EVENTUALLY NEED TO
INCREASE TEMPS A BIT MORE WITH SOME TREND OF SUBTLE FASTER TREND
WITH THIS FRONT FRI/SAT. MILD CONDITIONS TO CONTINUE SATURDAY WITH
HIGHS INTO THE 70S...BUT MUCH OF THE DETAILS REGARDING TEMPS WILL
DEPEND ON PRECIP COVERAGE/EXACT FRONTAL TIMING. THE END OF THE
PERIOD SHOULD BE SLIGHTLY COOLER BUT CLOSE TO SEASONABLE NORMS AS
BAROCLINIC ZONE IS LIKELY TO BE ANCHORED ACROSS THE REGION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 107 PM EDT TUE MAY 3 2016

PESKY SHOWERS AND MVFR CIGS ASSOCIATED WITH UPPER TROUGH REMAIN
JUST SOUTH OF KFWA AND NOT EXPECTED TO IMPACT TERMINAL. SKIES HAVE
CLEARED AT KSBN. COULD SEE SOME BKN VFR CIGS THIS AFTERNOON WITH
DIURNAL CU FIELD IN THE 4-6KFT RANGE. MID LEVEL CLOUDS AHEAD OF
NEXT SHORT WAVE CURRENTLY OVER LAKE SUPERIOR WILL MOVE BACK IN
THIS EVENING. CIGS WILL LOWER AFTER 06Z WITH SHOWERS AHEAD OF NEXT
COLD FRONT IMPACTING KSBN TOWARD 09-10Z. COLD FRONT AND SHOWERS
WITH LOWERING CIGS WILL MOVE EAST TO KFWA TOWARD 12-14Z. MOST
GUIDANCE TRENDS CIGS TO IFR AFTER DAYBREAK AT KSBN AND TOWARD 18Z
AT KFWA POST FRONTAL SO LEANED IN THAT DIRECTION GIVEN MODEL
CLUSTERING.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 8 AM WEDNESDAY TO 5 PM EDT THURSDAY
     FOR LMZ043-046.

&&

$$

SYNOPSIS...LASHLEY
SHORT TERM...MARSILI
LONG TERM...MARSILI
AVIATION...LASHLEY


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