Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 232315
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
715 PM EDT WED APR 23 2014

.SYNOPSIS...
ISSUED AT 1240 PM EDT WED APR 23 2014

A WEAK WARM FRONT WILL APPROACH THE REGION TONIGHT AND MAY
GENERATE A FEW SPRINKLES ACROSS NORTHWEST INDIANA AND SOUTHWEST
MICHIGAN. OVERNIGHT LOWS ARE EXPECTED TO HOLD IN THE UPPER 30S TO
LOWER 40S. WARMER AIR WILL OVERSPREAD THE AREA TOMORROW IN ADVANCE
OF A COLD FRONT WITH HIGHS FORECAST TO REACH THE MID TO UPPER 60S.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 404 PM EDT WED APR 23 2014

PRIMARILY ONLY MIDLEVEL MOISTURE TO OVERTOP UPSTREAM MID
TROPOSPHERIC RIDGE THAT EXTENDS FROM MO NORTHWARD INTO SOUTHERN
CANADA. MID LEVEL MOISTURE ALONG WITH TIMING OF WESTERLY MID LEVEL
JETLET TO MOVE FROM SRN IA AT 00 UTC THU TO CHICAGOLAND/FAR NWRN IN
BY 06 UTC TO PROVIDE FOCUS FOR POSSIBLE SPRINKLES. HIGH LOW LEVEL
CONDENSATION PRESSURE DEFICITS...ONLY LOWER BRIEFLY TO NEAR 50 MB IN
ROUGHLY 06-09 UTC TIMEFRAME ALONG FAR SOUTHEAST EXTENSION OF
ELEVATED WARM ADVECTION LEAF. MORE DEEPLY MIXED BOUNDARY LAYER ON
THU SUPPORT TEMPS ABOUT 5-10F WARMER THAN TODAY...LEAST MODIFICATION
ACROSS FAR NERN CWA WHERE CONCERN FOR BACKED/EASTERLY SURFACE
COMPONENT RAISES CONCERN FOR LAKE ERIE SHADOW/TIGHTENED THERMAL
GRADIENT. SLIGHT TREND TOWARD NEGATIVE TILT TO MID LEVEL TROF AS IT
ENTERS ERN ND/MID MS VLY BY F36 AND CONTINUED BACKED SOUTHEASTERLY
PREFRONTAL FLOW SUPPORTS NARROW THETA-E GRADIENT STRONGLY TIED TO
FRONTAL BOUNDARY AND HAVE SLOWED DOWN LATE AFTN/EVEN CHC SHRA WITH
LESSER TSRA MENTION GIVEN POOR LOW LEVEL MOISTURE POOLING THROUGH 00
UTC FRI.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 404 PM EDT WED APR 23 2014

A QUICK QUARTER TO HALF INCH OF RAIN STILL MODELED TO PIVOT EAST
THROUGH THE FORECAST AREA THURSDAY NIGHT ALONG A FRONTAL BOUNDARY.
HIGH POPS WARRANTED GIVEN A RELATIVELY DEEP UVM RESPONSE WITH AN
ASSOCIATED SHORTWAVE...AND MODEST LOW LEVEL THETA-E RIDGING
(1000-850 MB MIXING RATIOS NEAR 9 G/KG) ALONG AND IN ADVANCE OF THE
OCCLUDING FRONTAL BOUNDARY/WEAK SFC REFLECTION. PRIMARY ADJUSTMENT
TO THE FCST/GRIDS WAS TO DELAY TIMING OF HIGHER POPS THROUGH THE FA
PER SLOWER 12Z MODEL TRENDS. A BREEZY/MILD/MAINLY DRY FRIDAY
ANTICIPATED AS WELL MIXED DRY SLOT AND SUBSIDENCE OVERSPREADS THE
AREA. BRIEF FGEN RESPONSE WITH A SECONDARY COLD FRONT/PV FILAMENT
ON BACKSIDE OF PHASING WAVES MAY SUPPORT A FEW SHOWERS FRIDAY
NIGHT.

LONGWAVE PATTERN BECOMES INCREASINGLY BLOCKY/AMPLIFIED THIS WEEKEND
INTO NEXT WEEK. THE WEEKEND CONTINUES TO LOOK MAINLY DRY WITH ACTIVE
BAROCLINIC ZONE LIKELY SETTING UP SOUTHWEST OF THE LOCAL AREA.
ALSO...HIGH PRESSURE ATTEMPTS TO NUDGE SOUTH INTO THE LAKES IN
BETWEEN EMERGING NEGATIVE HEIGHT ANOMALIES OVER NEW ENGLAND...AND
ANOTHER OVER THE FOUR CORNERS/CENTRAL HIGH PLAINS.

UNSETTLED AND TRENDING COOLER NEXT WEEK AS HIGH PLAINS NEGATIVE
HEIGHT ANOMALY MEANDERS EAST...EVENTUALLY TEAMING UP WITH VORT LOBE
DROPPING SOUTHWEST OUT OF SE CANADA/GREAT LAKES TO FORCE A RATHER
IMPRESSIVE VERTICALLY STACKED/CUT-OFF LOW OVER THE MID MS/OH VALLEYS
BY THE MIDDLE OF THE WEEK. OBVIOUSLY A COMPLEX SYNOPTIC EVOLUTION
WITH CONFIDENCE IN DAILY TEMPS/POPS VERY LOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 714 PM EDT WED APR 23 2014

VFR CONDS TO CONT THROUGH THIS PD. UPSTREAM WAA WING AND BAND OF
ASSOCD HIGH BASED SHRA FM WRN WI SWD INTO CNTRL IL XPCD TO DISSIPATE
W/EWD EXTENT OWING TO EWD WKNG OF LL THETA-E/MSTR FLUX. IN FACT
GIVEN EXTREMELY DRY AND WELL MIXED BNDRY LYR DOUBT CIG HGTS BLO 8KFT
PSBL LT TONIGHT. OTRWS SERLY RTN FLW TO DEEPEN ON THU AHD OF SW
TROUGH EJECTING OUT OF THE SRN PLAINS. DEEPER/BETTER DEFINED LL
MSTR/THETA-E PUSH XPCD LT THU NIGHT W/PD OF SHRA AND LIKELY MVFR
CONDS IN ASSOCN/W FNTL BNDRY AND PARENT UPR TROUGH PROGRESSING
THROUGH THE AREA. UNTIL THEN SENSIBLE WX CONCERNS NIL.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...MURPHY/STEINWEDEL
SHORT TERM...MURPHY
LONG TERM...STEINWEDEL
AVIATION...T


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