Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 301042
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
642 AM EDT WED JUL 30 2014

.SYNOPSIS...
ISSUED AT 450 AM EDT WED JUL 30 2014

A STRONG LOW PRESSURE SYSTEM WILL REMAIN ANCHORED OVER JAMES BAY
CANADA REACHES SOUTH THROUGH WESTERN LAKE ERIE. THIS WILL RESULT
IN CONTINUED COOL WEATHER IN OUR AREA WITH SCATTERED...PRIMARILY
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH THE NEXT FEW DAYS.
HIGHS TODAY WILL GENERALLY REACH INTO THE MID 70S...THOUGH ONLY
NEAR 70 CLOSE TO LAKE MICHIGAN. LOWS TONIGHT WILL DROP BACK INTO
THE LOWER TO MIDDLE 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 446 AM EDT WED JUL 30 2014

ANTICIPATE SIMILAR SCENARIO AS SEEN YESTERDAY GIVEN HIGHLY BLOCKED
LONGWAVE PATTERN WITH DEEP LAYER TROF AXIS HOLDING FROM JAMES BAY
ANCHOR SOUTHWARD TO WESTERN LAKE ERIE. CONTINUED NWRLY PERTURBED
FLOW AMID STEEP 0-3KM LAPSE RATES PEAKING AT 7.5-8.25C/KM
MIDDAY/AFTERNOON WITH SFC/5H DIFFERENTIALS AGAIN IN UPPER 30C TO
NEAR 40C RANGE SHOULD BE SUFFICIENT FOR RENEWED CONVECTIVE
DEVELOPMENT BY LATE MORNING/MIDDAY. SURFACE DEWPOINTS HAVE CREPT
UPWARDS PER BOTH YESTERDAYS ISOLATED TO SCATTERED CONVECTION AS WELL
AS GENEROUS EVAPOTRANSPIRATION THROUGH CORN BELT. MODIFIED NAM12
POINT SOUNDINGS YIELD GENERALLY 600-800 J/KG WITH MID 70S/MID
50S...SAVE FOR ONLY ABOUT 250 J/KG DOWNWIND OF SOUTHEAST LAKE
MICHIGAN. WITH GREATER CONVERGENCE/INSTABILITY WELL INLAND AND ALONG
SOUTHEAST EXTENSION OF NERN IL/NWRN IN LAKE SHADOW...WILL OFFER SOME
SPATIAL DETAIL WITH COVERAGE TYPE WORDING...AND LOWER POPS AS WELL
AS NIX TSRA MENTION IN NWRN CWA CONCAVITY. AGAIN LITTLE LCL/LFC
DIFFERENTIAL SHOULD PROVIDE FAIRLY RAPID LOW TOPPED CONVECTIVE
DEVELOPMENT AND WET BULB ZERO HEIGHTS AROUND 9 KFT SUGGEST SMALL
HAIL WITHIN STRONGEST STORMS POSSIBLE. WEAKENING GRADIENT FLOW AND
REMNANT LOW LEVEL THERMAL TROF SUGGESTS ANOTHER GOOD LONGWAVE
RADIATIONAL EVENING/EARLY WED NIGHT AND LOWERED TEMPS
SLIGHTLY...ESPECIALLY AT KBEH WITH ANTICIPATED LAND BREEZE/DRAINAGE
WIND.

&&

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 446 AM EDT WED JUL 30 2014

CONTINUED SEASONALLY COOL MID LEVEL TEMPS ON THURSDAY WILL ALLOW
AFTERNOON LAPSE RATES TO STEEPEN WITH DAYTIME HEATING...AND SHOULD
ALLOW FOR A SLIGHT CHANCE FOR THUNDERSTORMS AS WEAK UPPER LEVEL
DISTURBANCES MOVE ACROSS THE AREA. WEAK UNIDIRECTIONAL WIND FLOW BUT
WITH LOW WET BULB ZERO HEIGHTS COULD ALLOW FOR SOME VERY SMALL HAIL
FROM A STORM OR TWO. THEREFORE...HAVE KEPT A SLIGHT CHANCE FOR
THUNDERSTORMS THURSDAY AFTERNOON. KEPT A LOW CHANCE OR SLIGHT CHANCE
FOR SHOWERS OR STORMS FRIDAY THROUGH SATURDAY AS THIS PATTERN
CONTINUES WITH ADDITIONAL WEAK SHORT WAVE ENERGY ROTATING AROUND THE
UPPER LOW THAT SHOULD BE OVER JAMES BAY EARLY THIS WEEKEND. THE
UPSTREAM UPPER LEVEL RIDGE SHOULD FLATTEN EARLY NEXT WEEK AND ALLOW
A MORE PROGRESSIVE UPPER LEVEL PATTERN. LOW LEVEL THETA E SHOULD
INCREASE TUESDAY...AND ALONG WITH WEAK LOW LEVEL FORCING...SHOULD
ALLOW FOR A SMALL CHANCE FOR THUNDERSTORMS TUESDAY. AS FOR
TEMPERATURES...FAVOR THE COOLER GFS MEAN ENSEMBLE TEMPERATURES WHICH
SEEM TO SUPPORT COOL 850 MB TEMPERATURES FOR THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 642 AM EDT WED JUL 30 2014

LITTLE CHANGE TO LATEST 12 UTC TAFS FOR NORTHERN INDIANA. PRIMARILY
VFR MET CONDITIONS THROUGH THE FORECAST PERIOD SAVE FOR MVFR
VSBSY NEAR DAYBREAK INVOF KFWA. OTHERWISE...SIMILAR SCENARIO AS
SEEN YDAY WITH MID TROPOSPHERIC COLD POOL REMAINING FROM NORTH OF
LAKE SUPERIOR INTO NWRN OH WITH SOLD/SCT CONVECTION POTENTIAL
INCREASING BY MIDDAY...AND HAVE ADDED MENTION OF VCTS AT KFWA 16-23
UTC GIVE HIGHER DEGREE OF CONFIDENCE...AND WILL MONITOR TRENDS
FOR POSSIBLE TEMPO INCLUSION LATER. SUFFICIENT INLAND SCOUR
DOWNWIND OF LAKE MICHIGAN SHOULD PRECLUDE SHRA/TSRA OCCURRENCE AT
KSBN.

&&

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

$$

SYNOPSIS...MURPHY
SHORT TERM...MURPHY
LONG TERM...SKIPPER
AVIATION...MURPHY


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