Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 230530
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
130 AM EDT WED APR 23 2014

.SYNOPSIS...
ISSUED AT 736 PM EDT TUE APR 22 2014

COLDER AIR WILL CONTINUE TO FILTER INTO THE AREA OVERNIGHT AS HIGH
PRESSURE DEEPENS OVER THE GREAT LAKES. LOWS TONIGHT WILL DROP TO
NEAR OR BELOW THE FREEZING MARK WITH PATCHY FROST POSSIBLE.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 343 PM EDT TUE APR 22 2014

STRONG ISENTROPIC DESCENT/LARGE SCALE SUBSIDENCE IN ADVANCE OF A
BUILDING MID LEVEL RIDGE WILL SUPPORT DRY CONDITIONS AND MAINLY
CLEAR SKIES TONIGHT INTO WEDNESDAY. GUSTY NORTHERLY WINDS WILL
QUICKLY SUBSIDE EARLY THIS EVENING WITH LOSS OF DEEPER DIURNAL
MIXING AND WEAKENING PRESSURE GRADIENT AS AN UPPER MIDWEST SFC RIDGE
BEGINS TO BUILD INTO THE LOCAL AREA. COLD/DRY CP AIRMASS AND
DECOUPLING UNDER CLEAR SKIES WILL ENSURE A CHILLY NIGHT WITH MOST
LOCATIONS DROPPING INTO THE LOW 30S. NO FROST/FREEZE HEADLINES
NEEDED WITH GROWING SEASON NOT IN FULL SWING YET...BUT DID CONTINUE
WITH A SPS GIVEN POTENTIAL FROST DAMAGE TO SENSITIVE OUTDOOR PLANTS
AND FLOWERS. TOMORROW WILL FEATURE LIGHT WINDS AND A 25-30F DIURNAL
TEMP RECOVERY UNDER HIGH PRESSURE.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 343 PM EDT TUE APR 22 2014

LONG TERM PERIOD WILL BEGIN WITH NEAR NORMAL TEMPERATURES WEDNESDAY
NIGHT INTO THURSDAY...AS LARGE SCALE RIDGE CENTERED OVER THE REGION
SLIDES TO THE EAST. WAA RESPONSE AHEAD OF DIGGING UPSTREAM S/W AND
DEEPENING SFC CYCLONE COULD YIELD SOME LIGHT PRECIPITATION ACROSS
WESTERN AND NORTHERN AREAS LATE WEDNESDAY NIGHT INTO EARLY THURSDAY
MORNING. NARROW MID LVL FRONTOGENETIC BAND/CORRIDOR OF ISENTROPIC
ASCENT IS PROGGED TO CLIP THE NORTHWEST HALF OF THE AREA AFTER 00Z.
WHILE THE MID LVL FORCING AND MOISTURE LOOK SUFFICIENT FOR THE
DEVELOPMENT OF MEASURABLE PRECIP...LOW LEVELS LOOK EXTREMELY DRY
WITH THE ONSET OF THE FORCING...AND REMAIN FAIRLY DRY BELOW 850 MB
THROUGH THE OVERNIGHT. WILL STICK WITH THE SPRINKLE MENTION IN THE
FCST...AS COMPACT NATURE OF THE FRONTAL BAND/FORCING LOOKS TO BE
INCAPABLE OF SUFFICIENTLY SATURATING THE LOW LEVELS AND PRODUCING
MEASURABLE PRECIP.

AFTER A PLEASANT DAY ON THURSDAY...WITH NEAR TO SLIGHTLY ABOVE
NORMAL HIGH TEMPS IN THE MID TO UPPER 60S...PRECIPITATION CHANCES
WILL INCREASE LATE THURSDAY AFTERNOON THROUGH THURSDAY NIGHT. A
FRONTAL BOUNDARY WILL APPROACH THE REGION FROM THE WEST...AS A
MID/UPPER S/W AND SFC LOW TRACK EAST ACROSS THE GREAT LAKES REGION.
LATEST MODEL SOLUTIONS GREATLY DIFFER WITH THE HANDLING OF THIS
SYSTEM. 12Z ECMWF REMAINS FARTHER NORTH WITH THE MID/UPPER LVL
ENERGY AND 500 MB JET...WITH A SEPARATE MID/UPPER LEVEL WAVE TRACKING
FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY. THE SOUTHERN
PERIPHERY OF THE TROF AXIS REMAINS NEUTRALLY TILTED...RESULTING IN A
SLOWER SOLUTION. 12Z GFS IS FARTHER SOUTH WITH THE MID LVL WAVE AND
JET...PHASING WITH THE SOUTHERN STREAM WAVE AS IT KICKS NORTHEAST
TOWARD THE REGION. THIS PHASED SYSTEM RESULTS IN A FASTER FRONTAL
PASSAGE. RESULTING FCST SOLUTION IS A BLEND OF THE PREVIOUS FORECAST
AND THE 12Z MODEL SOLUTIONS...WEIGHTED TOWARD THE 12Z ECMWF. THIS
FCST RESULTS IN POPS HOLDING OFF UNTIL 00Z EXCEPT FOR THE FAR WEST.
HELD WITH LIKELY POPS AND CHANCE THUNDER FROM 00Z TO 06Z...ALTHOUGH
THUNDER CHANCES LOOK MARGINAL AT BEST AT THIS POINT.

FORECAST CONFIDENCE CONTINUES TO DECREASE SIGNIFICANTLY FROM THIS
WEEKEND INTO NEXT WEEK. TEMPERATURES ON FRIDAY LOOK COMPARABLE TO
THURSDAY IN THE WAKE OF THE OCCLUDED FROPA...WITH TEMPERATURES IN
THE UPPER 60S TO LOW 70S. FRIDAY NIGHT AND BEYOND...LARGE SCALE
PATTERN BECOMES SIGNIFICANTLY UNCERTAIN WITH REGARDS TO TEMPERATURES
AND PRECIPITATION.

MODELS DEPICTING A SECONDARY FRONT SHIFTING SOUTH INTO THE AREA
FRIDAY NIGHT INTO SATURDAY...AS MID/UPPER S/W AND ASSOCIATED SFC LOW
TRACKS EAST OUT OF THE GREAT LAKES TOWARD NEW ENGLAND. THIS COULD
BRING SOME LIGHT RAIN SHOWER ACTIVITY TO THE AREA FRIDAY NIGHT...AND
BELOW NORMAL TEMPERATURES ON SATURDAY THROUGH THE WEEKEND.
NORTHERLY/NORTHWEST FLOW AND STRONG CANADIAN SFC HIGH PRESSURE LOOKS
TO REINFORCE THIS BAROCLINIC ZONE JUST SOUTH OF THE AREA...AND SHARP
MID/UPPER LEVEL RIDGING TAKES HOLD ACROSS THE PLAINS IN RESPONSE TO
DIGGING WRN CONUS UPPER TROF. THIS WOULD SUPPORT PERIODIC PRECIP
CHANCES ALONG THE BAROCLINIC ZONE...WITH BELOW NORMAL TEMPS FOR THE
AREA. THIS IS THE CONSENSUS FROM THE 12Z GFS AND GEFS MEAN. THE END
OF THE 09Z SREF AND 12Z GEM SUPPORT THIS IDEA...HOWEVER THE
BAROCLINIC ZONE DEPICTED IS FARTHER NORTH THAN THE GFS/GEFS
SOLUTION. THE 12Z ECMWF REMAINS THE FARTHEST NORTH WITH THE LATE
WEEK S/W...AND KEEPS THE SECONDARY FRONT UP ACROSS THE NORTHERN
GREAT LAKES THROUGH THE WEEKEND. THIS WOULD PLACE THE AREA IN THE
WARM SECTOR OF THIS SYSTEM...LIKELY YIELDING ABOVE NORMAL
TEMPERATURES FROM SATURDAY THROUGH MONDAY.

WITH THE WIDE RANGE OF SOLUTIONS...NO MAJOR CHANGES TO THE FORECAST
REGARDING TEMPS AND PRECIP AFTER FRIDAY NIGHT. HOWEVER...DID ADJUST
SATURDAY HIGH TEMPERATURES UP A FEW DEGREES...ESPECIALLY SOUTH...AS
MODELS AS A WHOLE ARE TRENDING TOWARD A SLOWER SOUTHWARD PUSH OF THE
SECONDARY FRONT...ALONG WITH DECREASING CONFIDENCE IN THE GEFS
MEAN...WITH 850 MB STANDARD DEVIATIONS AROUND 4C ACROSS THE LOWER
GREAT LAKES DURING THIS TIME PERIOD.

TOWARD THE END OF THE FCST PERIOD AND JUST BEYOND...MODELS STILL
INDICATE A MORE BLOCKED PATTERN ACROSS THE CONUS. LARGE CUTOFF LOW
LOOKS TO DEVELOP ACROSS THE CENTRAL CONUS BY MIDWEEK...AND SLOWLY
MEANDER ACROSS THE EASTERN CONUS. MEANWHILE...ANOTHER LARGE CUTOFF
LOW DEVELOPS ACROSS THE EASTERN PACIFIC/OFF THE CONUS WEST
COAST...WITH AN EXTREMELY AMPLIFIED WRN CONUS RIDGE. THIS BLOCK
WOULD PROVIDED AN EXTENDED PERIOD OF BELOW NORMAL TEMPS FROM MIDWEEK
THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND...ALONG WITH PERIODIC
PRECIPITATION CHANCES...FOR MUCH OF THE EASTERN CONUS..INCLUDING OUR
FORECAST AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 130 AM EDT WED APR 23 2014

VFR CONDITIONS WILL PERSIST THROUGH THE PERIOD AS APPROACHING
MIDLEVEL RIDGE AXIS ENSURES A DRY/SUBSIDENT ENVIRONMENT THROUGH
MOST OF THE DAY. GRADUAL TOP-DOWN SATURATION EXPECTED LATER TODAY
THOUGH AS WAA SLOWLY INCREASES AHEAD OF NEXT TROUGH. A FEW
SPRINKLES ARE POSSIBLE AT KSBN TOWARD THE END OF THE PERIOD BUT
VERY DRY CONDITIONS IN THE LOWER LEVELS WILL LIMIT RAINFALL
POTENTIAL AND KEEP CEILINGS WELL ABOVE 3 KFT.

&&

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

$$

SYNOPSIS...CEO
SHORT TERM...STEINWEDEL
LONG TERM...NG
AVIATION...AGD


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