444
FXUS63 KIWX 090815
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
415 AM EDT WED JUL 9 2008
SHORT TERM
TODAY THROUGH THURSDAY NIGHT. FEW ISSUES IN SHORT TERM. SHARP
ISODROSOTHERMAL BOUNDARY IMMEDIATELY TO WEST OF CWA TO PASS
THROUGH LATER THIS MORNING. AT 07 UTC 16F DP DIFFERENCE BETWEEN
NORTH AND SOUTH SIDE OF CHICAGO. BRIEF PRE-FIRST PD FOR LINGERING
SHRA IN SERN ZONES AHEAD OF FRONT WITH NO LTG ANTICIPATED GIVEN
WARMING CLOUD TOPS AND MID LVL FOCUS/JETLET WELL EAST OF CWA.
MINOR CONCERN WITH RESPECT TO SHALLOW GROUND FOG POTNL LATE
TONIGHT/EARLY THU AM...HOWEVER INSOLATION TODAY SHOULD BE
SUFFICIENT TO DRIVE XOVER TEMP LOW ENOUGH TO PRECLUDE NEED OF
MENTION ATTM...WITH SERN ZONES OF ONLY REAL CONCERN WHERE HIEST
RAFL AMOUNTS FELL AND LAST TO MIXOUT UNDER EARLY AM STRATUS THAT
EXTENDS FM KMIE-KFDY. PW CHANGE OF AROUND 1.5 INCHES LWR AND ONLY
WEAK/BROAD ML TROF TO NORTH TO AFFORD DRY SHORT TERM PD.
1000-850MB THETA-E RETURN THROUGH CENTRAL INTO NRN PLAINS THU
NIGHT WITH LLJ/MCS FOCUS REMAINING WELL WEST OF CWA WITH ANY
DEBRIS TO LIKELY RIDE TO NORTH AS STEERING FLOW BACKS AHEAD OF
MORE SIGNIFICANT NRN STREAM ENERGY THAT MOVES FM BC TO CENTRAL
CANADIAN PLAINS BY FRIDAY MORNING. FEW MINOR TWEAKS TO
TEMPS...WEAK PRES GRADIENT TONIGHT TO FAVOR DRAINAGE AT KBEH.
ALSO GIVEN DRY AIRMASS WITH LARGER DIURNAL SWINGS EXPECTED BUMPED
THU TEMPS WITH NEAR FULL SUN AS 925H TEMPS WARMING 5C/24HRS
FAVORS HIR END OF GUID FOR HIGHS THU.
LONG TERM
FRIDAY THROUGH TUESDAY.
RAPID RETURN OF HIGHER TEMPS AND MSTR STILL LOOKING ON TRACK AS
RIDGE DEPARTS TO THE EAST AND S-SW FLOW REESTABLISHES RAPIDLY. BOTH
GFS AND NAM SHOWING RAPID MSTR ADVECTION IN THE 12Z FRI TO 00Z SAT
TIME FRAME WITH SFC DEWPTS STARTING IN THE LOWER 60S AROUND 12Z
CLIMBING TO 70 TO 73 BY 00Z SAT. MODELS ALSO POINT TOWARDS MID TO
UPPER 80S FOR HIGHS...WHICH WILL YIELD A FAIR AMOUNT OF INSTABILITY
(GFS 1000-1500 J/KG VS NAM WITH 1500-2500 J/KG) AND LI'S IN THE -2
TO -6 C RANGE. SHEAR WILL ALSO BE INCREASING WITH BOUNDARY MOVING
THROUGH. NOT MUCH IN THE WAY OF A TRIGGER TO BE FOUND THOUGH TO ACT
ON WHAT LOOKS TO BE WAITING. GRIDS WILL NOT REFLECT THE MASSIVE
INCREASE AS OF YET BUT MAY NEED TO BE CHANGED IN THE NEAR
FUTURE. DRY FORECAST LOOKS TO BE THE WAY TO CONTINUE AT THIS POINT
BUT WILL NEED TO BE WATCHED.
COLD FRONT WILL ARRIVE SATURDAY BRINGING THE CHANCE FOR SHOWERS AND
STORMS. MUCH MORE UNSTABLE CONDITIONS MAY BE IN PLACE WITH CAPES
POTENTIALLY AOA 3000 J/KG AND LI'S OF -6 TO -9 C AS WELL AS FREEZING
LEVELS AROUND 10K. PWATS ALSO INCREASE TO AROUND 2 INCHES ONCE
AGAIN. ALL THESE COULD SPELL AN INTERESTING AFTERNOON AND EVENING
ACROSS THE AREA. FOR NOW WILL KEEP THE CHC POPS AS IS CONSIDERING
HOW EVEN WITH ALL THE POTENTIAL...HAVE HAD THIS SAME SCENARIO LATELY
AND ACTIVITY HAS BEEN MORE SCT IN NATURE.
FRONT WILL EXIT THE AREA. WARM UP THAT LOOKED TO BE ON TAP INTO NEXT
WEEK MAY BE POSTPONED A FEW DAYS AS GFS ADVERTISING A NICE POOL OF
COOL AIR TO COME DOWN WITH 850 MB TEMPS POSSIBLY DROPPING INTO THE
+7 TO +9 C RANGE. 8/12Z EURO SHOWS SLIGHTLY WARMER 850 TEMPS BUT
STILL MUCH COOLER THAN PREVIOUSLY THOUGHT. THESE TEMPS WOULD YIELD
POTENTIAL SFC TEMPS IN THE LOW TO MID 70S...WHICH THE MEX IS HINTING
AT ON MONDAY. ON THE EXACT SAME BASIS OF THE PAST FEW DAYS WITH
MODELS SHOWING THE SAME GENERAL IDEA AND NOW A COMPLETE FLIP WILL
NOT MAKE ANY DRASTIC CHANGES TO TEMPS INTO THE REMAINDER OF THE LONG
TERM PERIOD.
AVIATION
MID LEVEL WINDS CONT TO VEER ACRS NRN IN PER VWP/WLCI3 PROFILES
TAKING FOCUS FOR STRONG CONVECTION WELL TO EAST REMAINDER OF THE
NIGHT. GROWING CONCERN FOR PSBL IFR CIGS AT KFWA...FIRST WITH
FRONTAL BOUNDARY LAGGING WELL WEST FM WRN LWR MI-CHICAGOLAND-NERN MO
AND SECONDLY WITH CONTD DRIZZLE/-RA SATURATING BL OF AN ALREADY
MOIST ENVIRONMENT WITH RECORD DAILY RAFL 6/8...HAVE THEREFORE LWRD
CIGS FOR A PD NEAR/JUST AFTER SUNRISE. THEREAFTER VFR WITH INCREASED
MIXING WITH FRONTAL PASSAGE/DRY AIR ADVECTION. AT KSBN LESS RISK OF
LWRD CIGS WITH FRONTAL BNDRY JUST TO WEST WITH QUICKER MIXOUT IN
ANTECEDENTLY DRIER AIRMASS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
SHORT TERM...MURPHY
LONG TERM...FISHER
AVIATION...MURPHY
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