National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KIWX 141005
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
605 AM EDT TUE MAY 14 2013

.SYNOPSIS...
ISSUED AT 411 AM EDT TUE MAY 14 2013

A STRONG WARM FRONT WILL TRACK ACROSS THE SOUTHERN GREAT LAKES AND
OHIO VALLEY TODAY ALLOWING FOR MUCH WARMER CONDITIONS TODAY AND
WEDNESDAY. AN UPPER LEVEL DISTURBANCE TRACKING OUT OF THE PACIFIC
NORTHWEST WILL MOVE INTO ONTARIO TONIGHT. A COLD FRONT TRAILING
SOUTH FROM THIS DISTURBANCE WILL DROP INTO THE REGION ON WEDNESDAY
PROVIDING A CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY
AFTERNOON THROUGH THURSDAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 411 AM EDT TUE MAY 14 2013

STRONG ISENTROPIC UPGLIDE THIS MORNING HAS LED TO FAIRLY EXPANSIVE
MID CLOUD DECK. EXPECTING THIS MID LEVEL CLOUDINESS TO LINGER
THROUGH EARLY THIS MORNING AS SHEARED VORT MAX ASSOCIATED WITH UPPER
JET STREAK TOPPING UPPER RIDGE TO THE WEST NOSES INTO THE GREAT
LAKES REGION. SCATTERED SPRINKLES OR LIGHT RAIN SHOWERS HAVE BEEN
REPORTED ACROSS SOME OBSERVATION STATIONS IN WEST CENTRAL/CENTRAL
LOWER MICHIGAN THIS MORNING. SOME LOW END CHANCE STILL EXISTS FOR A
FEW OF THESE SPRINKLES AND SHOWERS TO MAKE IT INTO THE LOCAL AREA
OVER THE NEXT FEW HOURS. NET ISENTROPIC OMEGA PROGS FROM NAM DEPICT
MAXIMUM LIFT IN 300K-295K LAYER CENTERED TOWARD 12Z...ALTHOUGH BY
THIS TIME THE LOWER CONDENSATION PRESSURE DEFICITS SHIFT EASTWARD.
SUBCLOUD LAYER ALSO TO REMAIN VERY DRY THIS MORNING AND THUS
MEASURABLE PRECIP MAY BE TOUGH TO COME BY. BEST CHANCE OF A STRAY
HUNDREDTH OR TWO MAY BE ACROSS THE EXTREME NORTHEAST AND HAVE NOT
MADE MANY CHANGES TO INHERITED 20 POPS THIS MORNING BEFORE STRONGER
LIFT SHIFTS EAST OF THE AREA.

DECREASING CLOUDS ARE EXPECTED THIS AFTERNOON AS ZONE OF STRONGEST
MID LEVEL WAA SHIFTS INTO OHIO AND HEIGHT RISES ENSUE ACROSS THE
WESTERN GREAT LAKES. FAIRLY STRONG PRESSURE FALL MAX ON THE ORDER OF
4MB/3HR NOTED IN 07Z MSAS ANALYSIS ACROSS SOUTHEAST WISCONSIN WHICH
SHOULD TRANSLATE ACROSS LOWER MICHIGAN THIS MORNING. THE COMBINATION
OF DIURNAL MIXING AFTER 12Z COUPLED WITH A CONTRIBUTION TO THE
SOUTHERLY WINDS FROM PRESSURE FALL CENTER NORTH OF THE AREA SHOULD
BE CONDUCIVE FOR A PERIOD OF GUSTY SOUTH WINDS TO 25 TO 30 MPH FROM
MID MORNING THROUGH MID AFTERNOON. VERY STRONG LOW LEVEL WARM
ADVECTION WILL ALLOW FOR A DRAMATIC WARMUP IN TEMPERATURES TODAY AND
BIG QUESTION WILL BE JUST HOW DEEP WE ARE ABLE TO MIX GIVEN STRONG
WAA. NAM FCST SOUNDINGS DEPICT MIXING UP TO ABOUT 875 HPA THIS
AFTERNOON. SOME CONCERN THAT THIS COULD BE A BIT UNDERDONE DESPITE
THE WAA GIVEN RECENT DIFFICULTIES MODEL INITIALIZATIONS HAVE HAD IN
TERMS OF OVERDOING LOW LEVEL MOISTURE...WHICH IS ALSO EVIDENT IN 00Z
MODEL INITIALIZATIONS. HEDGING TOWARD SLIGHTLY DRIER LOW LEVEL
FORECAST...MIXED HEIGHTS COULD BE A BIT GREATER. PREVIOUS FORECAST
STILL APPEARS REASONABLE WITH LOWER TO MID 80S FAR WEST GIVEN ABOVE
FACTORS AND ONLY TWEAK MADE TO WAS TO SLIGHTLY WARM ESPECIALLY
EASTERN HALF INTO THE MID TO UPPER 70S. EXACT WEST TO EAST GRADIENTS
IN MAX TEMPS STILL A BIT ON THE LOW CONFIDENCE SIDE HOWEVER
CONSIDERING SHARP WEST TO EAST THERMAL GRADIENTS WITH THE WARM
FRONT. ALSO SOME LOWER CONFIDENCE ACROSS NORTHERN PORTIONS OF
BERRIEN COUNTY WHERE PRECISE SOUTH WIND DIRECTIONS WILL BE CRITICAL
FOR TEMP TRENDS. BY LATE AFTERNOON AS FLOW VEERS MORE
SOUTHWEST...LAKESHORE AREAS ACROSS EXTREME NORTHWEST COULD FALL BACK
INTO THE LOWER TO MID 70S.

FOR TONIGHT HIGHLY PROGRESSIVE AND COMPACT UPPER WAVE ACROSS PACIFIC
NORTHWEST THIS MORNING WILL TRACK INTO SOUTHERN ONTARIO ALLOWING A
FRONTAL BOUNDARY TO DROP SOUTHWARD ACROSS THE SOUTHERN GREAT LAKES.
ALTHOUGH MID LEVEL LAPSE RATES STEEPEN...UNIMPRESSIVE LOW LEVEL
MOISTURE PROFILES GIVE PAUSE TO ANY POP INCLUSION ACROSS THE FAR
NORTH. MILD CONDITIONS TONIGHT IN THE WARM SECTOR WITH LOWS
GENERALLY IN THE LOWER TO MID 60S.

&&

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 411 AM EDT TUE MAY 14 2013

A NORTHERN STREAM UPPER LEVEL WAVE PROPAGATING EAST THROUGH ONTARIO
INTO WESTERN QUEBEC IN PROGRESSIVE FLOW PATTERN WILL FORCE A SHALLOW
FRONTAL BOUNDARY SOUTH THROUGH THE FORECAST AREA WEDNESDAY
AFTERNOON/EVENING. SFC AMBIENT TEMPS WILL WARM NICELY IN WARM SECTOR
AHEAD OF THE FRONT WITH HIGHS REACHING THE UPPER 70S TO MID 80S.
SLIGHT MOISTURE POOLING WITH SFC DEWPOINTS 55-60F (GFS MID 60
DEWPOINTS LIKELY OVERDONE) SHOULD YIELD SBCAPE`S UP TO 1000 J/KG
WHICH HINTS AT THE POTENTIAL FOR A LATE DAY CONVECTIVE RESPONSE
ALONG THE FRONT. BULK OF 00Z GUIDANCE A LITTLE FASTER WITH THIS
FEATURE REACHING OUR SOUTHERN ZONES BY PEAK HEATING. AS A RESULT
REMOVED/LOWERED POPS ACROSS THE NORTHERN HALF OF THE FA BUT DID
CONTINUE WITH LOW/MID CHC POPS MAINLY 21-06Z IN THE SOUTH...WITH
LIMITING FACTORS FOR HIGHER POPS/COVERAGE BEING A LACK OF UPPER
LEVEL SUPPORT/COOLING IN BETWEEN SHORTWAVES IN SPLIT FLOW (NEARING
SOUTHERN STREAM DISTURBANCE AND DEEPER MOISTURE SHEAR SOUTH AND WEST
OF THE LOCAL AREA) AND INITIAL STRONG 850-800 MB CAPPING INVERSION.

SPREAD HAS CONTINUED TO NARROW AMONG LATEST NWP GUIDANCE WITH
THETA-E/INSTABILITY GRADIENT SETTLING JUST SOUTH OF THE AREA LATER
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THIS LENDS INCREASED
CONFIDENCE IN DRY CONDITIONS ACROSS THE NORTHERN HALF OF THE FA AS
HIGH PRESSURE BUILDS INTO THE GREAT LAKES. HELD ON TO LOWER CHC POPS
IN THE SOUTH GIVEN CLOSE PROXIMITY TO BOUNDARY.

LOW AMPLITUDE SHORTWAVE RIDGING INTO THE GREAT LAKES IN ADVANCE OF
AN AMPLIFYING WESTERN CONUS UPPER TROUGH IS EXPECTED FRIDAY INTO
SATURDAY. AT THE SFC EXPECT THE INCREASINGLY DIFFUSE FRONTAL
BOUNDARY TO ATTEMPT TO MIX BACK NORTH INTO THE AREA IN WEAKER
ISENTROPIC ASCENT/THETA-E ADVECTION REGIME. A LEAD CONVECTIVELY
ENHANCED/MODIFIED MCV MAY INTERACT WITH THIS NWD MIXING FRONT TO
BRING A PERIOD OF RAIN/THUNDER TO THE AREA...BEST CHANCES LATER
FRIDAY NIGHT/SATURDAY PER LAST SEVERAL MODEL CYCLES.

GLOBAL MODELS ARE IN OVERALL AGREEMENT IN TRANSITION TO A MORE
AMPLIFIED LONGWAVE PATTERN SUNDAY INTO MONDAY WITH WESTERN TROUGH
EJECTION INTO THE CENTRAL US. INCREASING SOUTHERLY FLOW EAST OF THE
DEVELOPING PLAINS/UPPER MIDWEST LOW PRESSURE SYSTEM WILL SUPPORT
RENEWED WARM/MOIST ADVECTION. GIVEN THIS RETAINED CHC POPS FOR
SHOWERS/STORMS (BETTER CHANCES MONDAY...POSSIBLY SEVERE GIVEN OPEN
GULF AND INCREASING SHEAR WITH SHORTWAVE ROUNDING BASE OF UPPER
TROUGH INTO THE REGION) AND WARMER TEMPS AS WARM FRONT EVENTUALLY
LIFTS NORTH OF THE AREA PER LATEST GFS/ECMWF PROGS.

AS FOR TEMPS THURSDAY THROUGH MONDAY...GENERALLY REMAINED CLOSE TO
WARMER MOS GUIDANCE OVER 00Z MODEL CONSENSUS INITIALIZATION...
ESPECIALLY SUNDAY INTO MONDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 604 AM EDT TUE MAY 14 2013

MID LEVEL WARM ADVECTION FORCED CLOUDINESS SHOULD GRADUALLY DEPART
FROM WEST TO EAST LATER THIS MORNING WITH MOSTLY SUNNY SKIES THIS
AFTERNOON. THE COMBINATION OF TIGHTENING GRADIENT OVERNIGHT AND
CONTRIBUTION FROM SFC PRESSURE FALLS TRACKING ACROSS LOWER
MICHIGAN SHOULD PRODUCE SOUTH WIND GUSTS OF AROUND 25 KNOTS FROM
MID MORNING TO MID AFTERNOON. WINDS WILL VEER SOUTHWESTERLY LATER
THIS AFTERNOON AS WARM FRONT CONTINUES TO LIFT NORTHWARD. A FAST
MOVING UPPER LEVEL DISTURBANCE ACROSS NORTHWEST CONUS WILL MOVE
INTO ONTARIO TONIGHT WITH A COLD FRONT TRAILING INTO THE WESTERN
GREAT LAKES TOWARD THE END OF THE PERIOD. ISOLD SHOWERS MAY
DEVELOP ALONG AND IN ADVANCE OF THIS FRONT TOWARD THE END OF THE
FORECAST PERIOD...BUT PERSISTENT DRY LOW LEVELS AND HIGH BASED
ISOLATED NATURE OF ANY POTENTIAL SHOWERS PRECLUDES A MENTION AT
THIS TIME.

&&

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

$$

SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...STEINWEDEL
AVIATION...MARSILI


VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA