AP-LM--IWX-IN Area Forecast Discussion, LM
000
FXUS63 KIWX 151103
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
703 AM EDT WED JUL 15 2015
.SYNOPSIS...
ISSUED AT 142 AM EDT WED JUL 15 2015
HIGH PRESSURE WILL SETTLE INTO THE REGION WEDNESDAY...PROVIDING
COOLER AND LESS HUMID CONDITIONS FOR MID WEEK. HIGHS ON WEDNESDAY
AND THURSDAY ARE FORECAST TO REACH THE MIDDLE TO UPPER 70S...WITH
LOWS THURSDAY MORNING DIPPING INTO THE LOWER TO MID 50S. HEAT AND
HUMIDITY...ALONG WITH RENEWED CHANCES FOR THUNDERSTORMS...WILL
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT WED JUL 15 2015
NIL SENSIBLE WX IN SHORT TERM WITH PRIMARY FOCUS ON TEMPS. DEEP
MID LVL VORTEX CENTROID ACRS LWR GRTLKS TO PUSH ESEWD OFF DELMARVA
COASTLINE BY AFTERNOON WHILE CONTINUING TO MINOR/FILL. IN NEAR
TERM...TRAPPED MOISTURE BENEATH SUBSIDENCE INVERSION ALLOWING
STRATUS WITH EVEN A FEW ISOLD TRANSITORY AREAS OF LIGHT DRIZZLE.
CLOUD COVER QUITE VARIABLE AND WITH CLOUD BEARING FLOW BECOMING
MORE NERLY DRIER AIR SHOULD CONT TO ADVECT INTO CWA THROUGH EARLY
AM HOURS. BLYR MIXOUT A FEW HOURS AFTER SUNRISE TO BRING CONTD
LWRG OF SFC DPS FOR MARKEDLY LESS HUMID DAY THAN PAST COUPLE.
STRONG INSOLATION TO OFFSET CORE OF THERMAL TROF THAT PRESENTLY
EXTENDS LK HURON-NERN CWA. FOR TONIGHT NERN TX RIDGE TO FLATTEN
AS CNTL ROCKIES SHORTWAVE ENERGY TOPS PERIPHERY INTO
PLAINS...ONLY SLIGHT UPTICK IN HIGH CLOUDS AS BULK MOISUTRE
REMAINS VERY LOW W/ PWAT FALLING TO NEAR 0.50 INCHES OVERNIGHT.
SFC RIDGE TO ONLY SHIFT SLIGHTLY FROM NRN GRTLKS AT PRESENT TO
SWRN ONT/SE LWR MI/ERN CWA. ANTICIPATE IDYLLIC LONGWAVE
RADIATIONAL LOSSES ALONG WITH COLD AIR DRAINAGE ALONG
LAKESHORE/KBEH...AND HAVE DROPPED MIN TEMPS A FEW DEGREES.
&&
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 352 AM EDT WED JUL 15 2015
ONE MORE COOL/QUIET/DRY DAY ON THURSDAY WITH STAUNCH LOW LEVEL
ANTICYLCONE AND THETA-E TROUGH IN PLACE. SOME WEAK LATE DAY WAA AS
WINDS SLOWLY VEER MAY ALLOW OUR SOUTHERN ZONES TO MAKE A RUN AT 80F
BUT STILL COOL BY MID JULY STANDARDS. MID/UPPER LEVEL CLOUDS WILL BE
ON THE INCREASE AS THE NEXT SYSTEM APPROACHES. THAT SYSTEM...A
CONVECTIVELY ENHANCED SHORTWAVE EJECTING OUT OF THE CENTRAL
PLAINS...WILL MARK THE LEADING EDGE OF A VERY ABRUPT AIRMASS CHANGE
AS MID/UPPER LEVEL FLOW TEMPORARILY BECOMES ZONAL AND ALLOWS ROBUST
THETA-E RIDGE TO FOLD EASTWARD INTO OUR REGION. MAIN CVA PASSES JUST
TO OUR NORTH BUT TIGHTENING GRADIENT OVER THE GREAT LAKES WILL LEAD
TO 30-40 KT LLJ AND STARK INCREASE IN LOW LEVEL THETA-E. SCT SHOWERS
AND STORMS POSSIBLE LATE THURSDAY NIGHT INTO FRIDAY
MORNING...ESPECIALLY ACROSS OUR NORTHERN ZONES CLOSER TO THE
SYNOPTIC FORCING AND BETTER LLJ. SOME SCT CONVECTION ALSO POSSIBLE
FRIDAY AFTERNOON GIVEN DECENT SURFACE BASED INSTABILITY. WEAK 800-
850MB CAP SEEN IN NAM AND GFS FORECAST SOUNDINGS IS A BIT CONCERNING
THOUGH GIVEN LACK OF ANY APPRECIABLE SYNOPTIC LIFT. WILL THEREFORE
KEEP POPS IN LOWER END CHANCE CATEGORY. SEVERE WEATHER UNLIKELY
GIVEN MODEST INSTABILITY AND SHEAR...THOUGH AN ISOLATED STRONG PULSE
STORM CANT BE RULED OUT.
RAIN CHANCES HIGHLY UNCERTAIN FOR THE WEEKEND. MOIST/UNSTABLE
AIRMASS WILL TAKE UP RESIDENCE WITH POTENTIAL FOR SEVERAL WEAK
SHORTWAVES TO TRAVERSE THE GREAT LAKES. HOWEVER...MIDLEVEL RIDGE
AMPLIFIES OVER THE GREAT LAKES DURING THIS TIME WITH MAIN STORM
TRACK JUST NORTH OF OUR AREA AND SOME CAPPING CONCERNS LOCALLY IN
WELL ESTABLISHED WARM SECTOR. JUST LOW CHANCES WARRANTED AT THIS
POINT. A FEW STRONG STORMS POSSIBLE GIVEN WARM/HUMID SURFACE
CONDITIONS BUT WARM MIDLEVELS AND WEAK FLOW ALOFT SUGGEST A LOW
THREAT FOR ORGANIZED SEVERE WEATHER. BETTER CHANCES FOR RAIN ON
MONDAY AS MORE FORMIDABLE TROUGH APPROACHES THE REGION...THOUGH
EXACT TIMING STILL A BIT UNCERTAIN AT THIS JUNCTURE.
OTHER MAIN STORY FOR THE LONG TERM WILL BE HIGH HEAT AND HUMIDITY
THIS WEEKEND. 850MB TEMPS SET TO SURGE INTO THE LOWER 20S ON
SATURDAY AND SUNDAY AS RIDGE AXIS BUILDS NORTHEAST. NOT SURE WE WILL
MIX QUITE THAT HIGH BUT TEMPS NEAR 90F STILL EASILY SUPPORTED.
MEANWHILE SURFACE DEWPOINTS WILL CLIMB WELL INTO THE MID 70S DUE TO
RECENT WET CONDITIONS AND WELL ESTABLISHED VEGETATION...AGRICULTURAL
AND OTHERWISE. HEAT INDICES WILL LIKELY MAKE A RUN AT 100F AND
HEADLINES MAY EVENTUALLY BE NECESSARY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 700 AM EDT WED JUL 15 2015
LITTLE SUBSTANTIVE CHANGE WRT 12 UTC TAFS FOR NRN INDIANA. CONTD
DRY AIR ADVECTION FOLLOWED BY MIXOUT INTO DRIER AIR ABOVE
SUBSIDENCE INVERSION TO ASSURE VFR MET CONDS THROUGH THE FCST PD.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...BEACH HAZARDS STATEMENT UNTIL 1 PM CDT THIS AFTERNOON FOR INZ003.
MI...BEACH HAZARDS STATEMENT UNTIL 2 PM EDT THIS AFTERNOON FOR MIZ077.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LMZ043-
046.
&&
$$
SYNOPSIS...MURPHY
SHORT TERM...MURPHY
LONG TERM...AGD
AVIATION...MURPHY
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Delivered by Weather Underground Inc. Wed Jul 15 2015 7:03AM EDT