FXUS63 KIWX 302120
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
420 PM EST MON NOV 30 2009

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...

FLOW BEGINNING TO COME AROUND TO MORE WEST AND SOUTHWEST IN RESPONSE 
TO NEXT WAVE DROPPING THROUGH THE UPPER PLAINS. AS A RESULT...SKY 
COVER IS BEGINNING TO ERODE SOMEWHAT ACROSS FAR WESTERN PARTS OF THE 
AREA WITH THIS TREND EXPECTED TO CONTINUE INTO THE FIRST PART OF THE 
EVENING. MID AND HIGH CLOUDS WILL INCREASE THOUGH...ESPECIALLY IN 
NORTH AND NW SECTIONS DURING THE EVENING AS THE UPPER LEVEL SYSTEM 
DRAWS CLOSER. TRACK OF THE SYSTEM LOOKS TO REMAIN QUITE A BIT NORTH 
OF THE AREA WITH NORTHERN PARTS ON THE SOUTHERN FRINGE OF THE 
EFFECTS OF IT. AS A RESULT...POPS HAVE BEEN TONED DOWN SOME WITH LOW 
CHC POPS ACROSS THE MI COUNTIES RAPIDLY TAPERING TO NOTHING 
GENERALLY SOUTH OF 30. WHILE IT LOOKS LIKE AT LEAST SOME RAIN OR 
SNOW FLAKES WILL OCCUR...CHANCES OF MEASURABLE PRETTY SLIM. WINDS 
WILL INCREASE SOMEWHAT IN RESPONSE TO A TIGHTENING GRADIENT BUT MAIN 
EFFECTS WILL BE CLOSER TO AND OVER THE LAKE VS INLAND. CHANCES FOR 
PRECIP WILL END QUICKLY OVERNIGHT ALLOWING FOR DRY CONDITIONS AND A 
DECREASE IN CLOUD COVER MAINLY INTO TUESDAY. 

WAA WILL BE ONGOING TONIGHT WITH 850 MB TEMPS OF -4 TO -8 C QUICKLY 
BEING REPLACES BY +2 TO +4 C TEMPS BY TUESDAY EVENING. THIS COMBINED 
WITH PARTLY TO MOSTLY SUNNY SKIES SHOULD ALLOW HIGHS TO BE A GOOD 5 
TO 10 DEGREES WARMER COMPARED TO TODAY WITH READINGS TOPPING OUT IN 
THE UPPER 40S TO POSSIBLY LOW 50S IN SE AREAS. HIGH CLOUDS WILL 
START TO INCREASE BY TUESDAY NIGHT...BUT WILL STILL ALLOW FOR 
OVERNIGHT LOWS TO DROP INTO THE MIDDLE 30S. 

&&

.LONG TERM...
WEDNESDAY THROUGH MONDAY. FEW CHNGS AGAIN TO WELL CONSISTENT FCST. 
TWO MAJOR FCST ISSUES REVOLVE AROUND TN VALLEY INTO OHIO VALLEY 
CYCLOGENESIS FOLLOWED BY FIRST GOOD ACCUMULATING LES POTNL. 
PREFERENCE LIES WITH MANY GEFS MEMBERS AND GEM AND TO LESSER EXTENT 
OP GFS INTO MID WEEK WITH SLOWER/FURTHER NW PHASING OF SRN/NRN 
STREAM ENERGIES AND SUBSEQUENT SOUTHERN TO MIDDLE GRTLKS STRONG 
MIDLVL CIRC. ECMWF DISPLACED MUCH FURTHER NORTH CLOSER TO JAMES BAY. 
SOUTHERN SYSTEM TO PULL BROAD AND DECENT LLVL GOMEX TAP WITH AROUND 
4 G/KG IN 1000-850MB LYR REACHING INTO FAR SOUTHEASTERN CWA LATE 
AFTN WED INTO WED NIGHT. I295K LIFT WITH STRONG WARM CONVEYOR BELT 
FLOW ORTHOGONAL TO PRESSURE SFC FOR ASCENT. HAVE CONTD EARLIER TREND 
OF HIR POPS WED AFNT AND ESPCLY WED NIGHT...WITH CHANGEOVER TO WET 
SNOW LATE WED NIGHT AS SFC LOW MOVES INTO WRN PA BY 06 UTC THU. 

THU INTO FRIDAY NIGHT FAVORABLE ACCUMULATING LES POTNL SETTING UP. 
LAKE EFFECT SNOW PARAMETERS PER GFS DOWN CONSIDERABLY OVER 24 HRS 
PREVIOUS WITH PRIMARY LIMITING FACTOR THE RH DEFICITS IN 850-700 MB 
LYR AND TO AN ALBEIT LESSER EXTENT WIND SPEED WITHIN 1000-850 MB 
LYR. STILL WITH CBL PERSISTENTLY WITHIN DGZ AND FAVORABLE AND DELTA 
T IN UPPER TEENS TO NEAR 20 WITH LAKE INDUCED CAPES 500-600 J/KG 
ANTICIPATE SOME IMPACT WITH EVENT...HOWEVER DUE TO LACK OF MODEL 
CONSISTENCY AND DY3-4 TIMELINE STILL BEYOND TRUE GRASP OF A 
MESOSCALE NATURE EVENT HAVE RELEGATED CHNGS TO A SLIGHT BUMP ACRS 
FAVORED NWRN COUNTIES THU NIGHT. BEYOND LES EVENT UNCERTAINTY 
ABOUNDS WITH GFS BRINGING LAST VESTIGES OF GULF OF AK ENERGY INTO 
NRN ROCKIES REGN SUNDAY MORNING THEN SPLITTING OFF A S/WV WITH SFC 
REFLECTION TRACKING EWD INTO MID MS VLY THEN LIFTING NE INTO GRTLKS 
SUNDAY NIGHT. PREFERENCE/RECOGNITION WOULD FAVOR A SLOWER DIGGING 
THROUGH WRN STATES BEFORE EJECTING AND HAVE HELD OFF ON MENTION TILL 
MONDAY/DY7 WITH JUST LOW CHCS AND A RASN MIX WITH PTYPE UNCERTAINTY 
AS WELL. 

&&

.AVIATION
VFR CONDITIONS TO CONTINUE AT BOTH SITES THROUGH THE PERIOD. LAKE
EFFECT CLOUD COVER HAS STREAMED SOUTHEAST AS FAR AS KFWA REQUIRING
MINOR CHANGES TO THE START OF THE TAF PERIOD. A PERIOD OF CLEARING
MAY BRIEFLY OCCUR TOWARDS EVENING AS THE FLOW BEGINS TO BECOME
MORE SW BUT FAST MOVING WAVE DROPPING IN FROM MINNESOTA WILL
SPREAD MID/HIGH CLOUDS ACROSS THE AREA THIS EVENING. MAIN CONCERN
WILL BE INCREASING WIND FIELDS AND POTENTIAL FOR LL WIND SHEAR.
SOUNDINGS SHOW A CLOSE CALL IN TERMS OF CRITERIA BUT IF WINDS OF
45 TO 50 KTS DO MATERIALIZE BETWEEN ROUGHLY 1500 AND 2500 FEET
THEN INDEED A WIND SHEAR ISSUE WOULD EXIST. HOWEVER...MODELS HAVE
BEEN RUNNING A BIT HIGH ON WINDS IN THESE SITUATIONS SO AGREE WITH
PREVIOUS SHIFT THAT A SLIGHTLY MORE RESERVED SHEAR MENTION IS
WARRANTED FOR NOW.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 PM EST TUESDAY FOR LMZ043-046.

&&

$$

SHORT TERM...FISHER
LONG TERM...MURPHY
AVIATION...FISHER