694
FXUS63 KIWX 130039
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
839 PM EDT MON MAY 12 2025
KEY MESSAGES
- VERY WARM WITH INCREASING HUMIDITY IN THE DAYS AHEAD WITH
HIGHS IN THE 80S THROUGH MIDWEEK.
- PERIODIC SHOWERS AND STORMS EXPECTED MUCH OF THE WEEK, MAINLY
DURING THE AFTERNOONS. LATER THURSDAY INTO THURSDAY NIGHT HAS
A CHANCE FOR SEVERE WEATHER.
DISCUSSION
ISSUED AT 218 PM EDT MON MAY 12 2025
AN UPPER LOW PRESSURE SYSTEM IS ABLE TO SHIFT NORTHWARD IN A
WEAKNESS IN THE FLOW AS A TROUGH ENTERS THE WESTERN US. AS IT DOES
SO, ITS OUTER EDGES OF ENERGY PUSHES INTO THE AREA AND MOISTURE WILL
BE ADVECTED INTO THE AREA AS WELL. AS SUCH, EXPECT SURFACE DEW
POINTS TO INCREASE FROM THE 40S THIS MORNING TO THE 60S BY 00Z THIS
EVENING. THIS IS MAYBE A LITTLE ON THE EARLY SIDE FOR THESE DEW
POINTS TO COME IN WHEN COMPARED TO NORMAL FOR FORT WAYNE'S OBS, BUT
IT'S NOT UNHEARD OF AND IT MAKES SENSE WITH A STRONG LOW LEVEL JET
CRANKING MOISTURE INTO THE AREA WITH CONNECTION TO THE WESTERN
ATLANTIC. CLOSER TO HOME, THE ISSUE WITH GETTING PRECIPITATION IS
THAT THERE'S SO MUCH DRY AIR AFTER OUR STRETCH OF DRY WEATHER
STARTING LATER LAST WEEK. EAST WINDS CLOSER TO THE SURFACE IS MORE
OF DRYING WIND AND RAP TIME SECTIONS SHOW THE DEPTH OF THE DRY AIR
AT LEAST THROUGH MIDDAY AT FWA AND WE'LL LIKELY HAVE TO WAIT UNTIL
MID AFTERNOON AT THE EARLIEST TO RECEIVE ANY RAIN. DESPITE THE NAM
SHOWING 500 TO 1000 J/KG OF INSTABILITY AROUND, THE ECMWF IS MUCH
MORE RESERVED WITH ONLY 500 J/KG AT 18Z AND THEN WANING AFTER THAT.
SIMILARLY THE HREF PROBABILITY OF THUNDER IS VERY RESERVED, LIMITING
EVEN 10 PERCENT CHANCES ON OUR DOORSTEP UNTIL TUESDAY AFTERNOON. SO,
WILL KEEP THUNDER CHANCES OUT UNTIL TUESDAY.
BY TUESDAY, THE UPPER LOW PRESSURE SYSTEM IS IN THE TENNESSEE RIVER
VALLEY. THE LOW LEVEL JET AXIS OVER THE AREA TODAY WILL BE MORE TO
OUR EAST ON TUESDAY, BUT 850 MB THETA-E WILL BE A LITTLE TOMORROW
AFTERNOON/EVENING THAN TODAY. BETWEEN 1000 TO 2000 J/KG OF MUCAPE
WILL BE AROUND TUESDAY AFTERNOON AND THAT COINCIDES WITH THE HREF
THUNDER OUTPUT MENTIONED EARLIER. THIS IS LIKELY MORE SCATTERED
SHOWERS/STORMS AND SHEAR APPEARS LACKING KEEPING THIS SUB-SEVERE. A
SIMILAR DAY FOR CHANCES FOR SHOWERS/STORMS IS EXPECTED ON WEDNESDAY
WITH THE UPPER LOW'S ENERGY NOW OVERHEAD TO BEGIN TO SHIFT EASTWARD.
SIMILAR INSTABILITY READINGS EXIST AND LEGITIMATE KEEPING KEEPING
SHOWERS AND STORMS IN THE FORECAST ESPECIALLY FOR THE AFTERNOON.
RIDGING MOVES IN FOR WEDNESDAY NIGHT INTO THURSDAY AS THE UPPER LOW
MOVES OUT, EAST OF THE AREA GIVING WAY TO A TROUGH HOT ON ITS HEELS.
SURFACE DEW POINTS REACH THE MID 60S AND APPROACH 70 DEGREES ON THE
ECMWF AND 850 MB TEMPERATURES APPROACHES 18C BY DAY'S END. SO,
SHOULD MAXIMUM HEATING BECOME REALIZED, 90 DEGREES IS NOT OUT OF THE
QUESTION. 90 DEGREE TEMPERATURES CERTAINLY HAVE BEEN DONE BEFORE,
BUT IT MAY BE A LITTLE ON THE EARLY SIDE CLIMATOLOGICALLY. AT THE
VERY LEAST, TEMPERATURES WELL INTO THE 80S CAN BE EXPECTED AS LONG
AS DEBRIS CLOUDS FROM WED NIGHT/THU AM RAIN DON'T ELIMINATE THE
CHANCES. THAT LINGERING RIDGING MAY BE ABLE TO KEEP US FROM
THAT. BETTER KINEMATICS ARRIVE LATER DAY AND THAT'LL HELP TO
INCREASE SHEAR THAT CAN BE TAPPED INTO BY STORMS THAT MAY FORM.
ONE INTERESTING SIGNAL ON THE GFS IS THAT SHEAR DROPS OFF ACROSS
THE AREA AROUND 00Z WHICH MAY BE AS A RESULT OF ITS MODELED
CONVECTION. SOUTHERN AREAS MAY BE ABLE TO SEE 2000 J/KG OF
MUCAPE ACCORDING TO THE ECMWF. ONE ISSUE FOR CONVECTIVE
INITIATION CHANCES COULD BE FORCING, WHICH APPEARS TO BE FAIRLY
WEAK, ESPECIALLY IF CAPPING TAKES HOLD WITH THESE HOT
CONDITIONS. A COLD FRONT FINALLY ARRIVES RIGHT AROUND 4 OR 5Z.
GFS-MODELED HELICITY ACTUALLY PUSHES INTO NW OH ALREADY BY 00Z,
WHICH IS DISCONNECTED FROM OTHER INGREDIENTS. MID LEVEL LAPSE
RATES AROUND ALSO BETWEEN 7 AND 8 C/KM WITH 900 J/KG OF DCAPE
LINGERING BEHIND AN INITIAL BATCH OF OVER 1000 J/KG DURING THE
AFTERNOON. ALL THIS TO SAY THAT ALL THREATS ARE ON THE TABLE,
BUT THAT THERE ARE QUESTIONS WITH INGREDIENTS LINING UP TO GET
THOSE THREATS OUT OF THE STORMS.
THETA-E OUTPUT SHOWS THE ATMOSPHERE IS OVERTURNED ON FRIDAY AFTER
THE COLD FRONT GOES THROUGH, BUT MODELS STALL THE FRONT JUST TO OUR
SOUTH IN SOUTHERN INDIANA. AS A RESULT, ENOUGH BAROCLINIC
INSTABILITY IS AROUND TO ALLOW ANOTHER INSTANCE OF SHOWERS AND
STORMS THERE. REALLY ON 500 TO 1500 J/KG OF MUCAPE EXISTS ACROSS THE
AREA ACCORDING TO THE GFS (LESSER ON THE ECMWF) SO THE STORM CHANCE
IS LESSER, BUT NOT NEGLIGIBLE. WILL CARRY SLIGHT TO CHANCE POPS FOR
LATER FRIDAY INTO FRIDAY NIGHT FOR THIS CHANCE FOR RAIN/STORMS.
AGAIN, IT LOOKS LIKE ANOTHER DRY WEEKEND IS IN STORE AS THE UPPER
THAT AFFECTS US LATE WEEK AND TRAVERSES NORTH OF THE AREA FINALLY
SHIFTS EASTWARD, AWAY FROM THE AREA.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 814 PM EDT MON MAY 12 2025
VFR CONDITIONS TO START THE PERIOD WITH LIGHT SHOWERS AROUND AND
E-SE FLOW, HOWEVER EXPECT SOME DETERIORATION TO MVFR/POSSIBLY
IFR AS A LOW PRESSURE SYSTEM MOVES IN OVERHEAD TONIGHT. AS OF
THIS WRITING, MODELS ARE FORECASTING TOO LOW OF CEILINGS BASED
ON SURROUNDING OBSERVATIONS AND THOSE UPSTREAM-SO WAS NOT AS
PESSIMISTIC WITH THE IFR CONDITIONS AS PREVIOUS FORECAST. STILL,
DO EXPECT SOME LOWERING GIVEN THE SYSTEM MOVING IN TONIGHT, WITH
ANY SHOWER ACTIVITY FAIRLY LIMITED. MOST OF THE GUIDANCE DROPS
CEILINGS TONIGHT TO AROUND 700 TO 1500 FT AT KFWA [SLIGHTLY
HIGHER AT KSBN MORE IN THE 1500-3000 FT RANGE OUTSIDE OF A FEW
BRIEF PERIODS LATER TONIGHT/TUE AM]. WE'LL SEE A BREAK IN THE
SHOWER ACTIVITY IN THE LATE MORNING/EARLY AFTERNOON BEFORE WE
HAVE CHANCES FOR SCATTERED SHOWERS AND MAYBE EVEN A FEW
THUNDERSTORMS IN THE MID-LATE AFTERNOON. HAVE HANDLED T-STORM
CHANCES WITH PROB30'S FOR NOW GIVEN LOWER CONFIDENCE ON EXACT
TIMING/LOCATION.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...ROLLER
AVIATION...MCD
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