Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 272314
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
714 PM EDT MON OCT 27 2014

.SYNOPSIS...
ISSUED AT 114 PM EDT MON OCT 27 2014

UNSEASONABLY WARM AIR WILL BE OVER THE REGION THIS AFTERNOON WITH
AFTERNOON HIGHS WELL INTO THE 70S. A STRONG COLD FRONT WILL BRING
SHOWERS AND POTENTIALLY A FEW THUNDERSTORMS TONIGHT INTO TUESDAY
MORNING...WITH DRIER AND COOLER AIR FUNNELING BACK IN FOR THE
MIDDLE OF THE WEEK.

&&

.UPDATE...
ISSUED AT 714 PM EDT MON OCT 27 2014

SUBTLE BAND OF ENHANCED MOISTURE CONVERGENCE AND ISENTROPIC ASCENT
IS CURRENTLY TOUCHING OFF A FEW SHOWERS AND THUNDERSTORMS ACROSS
THE AREA WITH THE HELP OF STEEP MIDLEVEL LAPSE RATES. LOWER LEVELS
ARE STILL RELATIVELY DRY AND QPF AMOUNTS HAVE BEEN LIGHT BUT DID
EXPAND AND PUSH UP THE TIMING OF POPS FOR THE EARLY OVERNIGHT
PERIOD IN LIGHT OF LATEST RADAR IMAGERY AND CG LIGHTNING REPORTS.
STILL EXPECT PRECIP TO EXPAND IN OUR NORTHWEST COUNTIES LATER
TONIGHT AS COLD FRONT APPROACHES SO NO MAJOR CHANGES AFTER
06Z...AN IDEA SUPPORTED BY LATEST HRRR AND RAP GUIDANCE.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 309 PM EDT MON OCT 27 2014

REASONABLY GOOD MODEL AGREEMENT FOR TONIGHT INTO TUESDAY WITH
APPROACHING COLD FRONT AND PCPN CHANCES. WATER VAPOR THIS
AFTERNOON CLEARLY SHOWS PARENT LOW OVER THE NORTHERN PLAINS WITH
PLUME OF DEEP MOISTURE OVER THE SOUTHERN PLAINS INTO THE MS VALLEY
REGION STREAMING NORTHEAST TOWARD OUR AREA. MAIN SHORT WAVE RIDING
AROUND BASE OF UPPER LOW AND SHOULD MOVE THROUGH HERE LATER
TONIGHT. INCREASING MOISTURE ADVECTION THROUGH THE EVENING WITH
INITIAL WEAK LEAD SHORT WAVE AND INCREASING LOW LEVEL JET TO 50
KNOTS MAY AID IN A FEW SCATTERED LIGHT SHOWERS OVER NORTHERN HALF
OF THE CWA EARLY THIS EVENING. HIRES GUIDANCE ALL SHOWING THIS
DEVELOPMENT WHILE AFTERNOON RADAR MOSAIC INDEED SHOWS SHOWER
DEVELOPMENT ALREADY BEGINNING OVER EASTERN MO INTO WESTERN IL.
WILL ACCOUNT FOR THIS WITH A LOW TO MODERATE POP FROM 00Z THROUGH
06Z THEN RAMPING UP POPS AFTER 06Z...ESPECIALLY OVER WESTERN AREAS
AS MAIN SHORT WAVE APPROACHES. EXPECT BURGEONING AREA OF PCPN
UPSTREAM THIS EVENING WITH BEST FORCING AHEAD OF SHORT WAVE WHICH
SHOULD THEN SPREAD ACROSS THE CWA LATE TONIGHT AND TUESDAY
MORNING. THUNDERSTORMS REMAIN POSSIBLE GIVEN MOISTURE AND DYNAMICS
BUT NOT EXPECTING SEVERE WEATHER. COULD SEE A FEW ISOLATED STRONG
WIND GUSTS WITH STRONGEST UPDRAFTS GIVEN LOW LEVEL JET.

SPEED OF SYSTEM AND DISTANCE CURRENTLY BETWEEN PARENT LOW AND
MOISTURE FEED SUPPORT STRONG DRY SLOT MOVING IN TUESDAY QUICKLY
ENDING PCPN FROM WEST TO EAST. MODEL DEPICTIONS SHOW STRONG
SUBSIDENCE AND DRYING WITH SKY CONDITIONS EXPECTED TO BECOME MOSTLY
SUNNY. A BIT CONCERNED ABOUT STRATOCUMULUS FILLING IN DURING THE
AFTERNOON WITH COLD AIR ADVECTION ALOFT BUT NOT READY TO GO AGAINST
SUBSIDENCE AND PRIOR TRENDS AT THIS TIME.

LOWS TONIGHT LIKELY TO REMAIN IN THE 60S MOST AREAS WITH CLOUD COVER
AND WINDS. TEMPS NOT EXPECTED TO DO MUCH ON TUESDAY WITH MORNING
COLD FRONT PASSAGE. COLDER AIR INITIALLY SLOW TO INFILTRATE...LIKELY
BEING OFFSET BY CLEARING AND DIURNAL SUN IN EARLY AFTERNOON. SHOULD
SEE TEMPS FALL MORE RAPIDLY MID TO LATE AFTERNOON AS SUN BEGINS TO
SET AND COLD WEDGE DEEPENS OVER THE AREA...ESPECIALLY IF MORE CLOUD
COVER DEVELOPS. HIGHS IN THE LOW TO MID 60S EXPECTED SOMEWHERE IN
THE MORNING TO EARLY AFTERNOON HOURS.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 309 PM EDT MON OCT 27 2014

PERIOD WILL START ON THE QUIET SIDE WITH NEAR TO SLIGHTLY BELOW
NORMAL TEMPERATURES AS A WEST TO NORTHWEST FLOW HOLDS ACROSS THE
REGION. MODEST WARM AIR ADVECTION WILL TRY TO NOSE IN THURS INTO
THURS NIGHT AHEAD OF A STRONG PIECE OF ENERGY WHICH WILL BREAK OFF
FROM LOW PRESSURE OVER NORTHERN CANADA. FOLLOWING THE FAR SUPERIOR
ECMWF OF THE PAST SEVERAL WEEKS IN THESE MORE ENERGIZED PATTERN A
BRIEF BUT POTENT SHOT OF COLD AIR WILL ARRIVE FRIDAY INTO SATURDAY
WITH MUCH BELOW NORMAL TEMPERATURES AND A CHANCE FOR RAIN SHOWERS
BOTH WITH PASSAGE OF THE SURFACE COLD FRONT AND IN ITS WAKE WITH
FLOW OFF LAKE MICHIGAN. AT THIS POINT...BULK OF THE COLDEST AIR WILL
BYPASS THE FORECAST AREA BUT THAT BEING SAID 850 MB TEMPS WILL STILL
DROP INTO THE -6 TO -8 C RANGE AT 850 MB. ANY PRECIPITATION WITH THE
SYSTEM SHOULD BE ON THE LIGHTER SIDE. WITH THE AMOUNT OF COLD AIR
COMING IN AND 1000-850 MB THICKNESSES DROPPING BELOW 1300 M...THE
CONCERN IS RAISED FOR A BIT OF WET SNOW BEING MIXED IN FRIDAY
AFTERNOON. SOUNDINGS SHOW BELOW FREEZING TEMPS THROUGH 925 MB...BUT
SFC TEMPS SUGGEST READINGS AROUND 40. A MENTION OF SNOW MAY NOT HURT
IN FAR NE AREAS BUT HOLDING OFF FOR NOW WITH BEST TIME FRAME
OCCURRING AS BEST PRECIP CHANCES ARE DEPARTING.

AS MENTIONED...COLD AIR WILL BE SHORT AS DEEP UPPER LOW PIVOTS OFF
THE NEW ENGLAND COAST WITH A CONTINUED BUT MORE RELAXED NW FLOW IN
TERMS OF COLD AIR ALOFT ALLOWING FOR TEMPS TO BEGIN TO MODERATE BACK
TOWARDS NORMAL BY MONDAY AS WARM FRONT BEGINS TO MOVE TOWARDS THE
REGION. ECMWF SUGGESTS SOME LIGHT PRECIPITATION ON THE NOSE OF
INCREASING THETA E BUT WITH AMOUNT OF DRY AIR STILL IN PLACE WILL BE
SOMEWHAT CONSERVATIVE AND KEEP TONED DOWN ESPECIALLY IN EASTERN
AREAS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 714 PM EDT MON OCT 27 2014

SHOWERS AND THUNDERSTORMS GRADUALLY EXPANDING THIS EVENING ALONG
SUBTLE BAND OF ENHANCED ISENTROPIC ASCENT/MOISTURE CONVERGENCE.
STEEP MIDLEVEL LAPSE RATES HAVE LED TO SCT THUNDERSTORMS DESPITE
DRY LOW LEVELS AND HIGH CLOUD BASES. LIGHTNING WILL BE THE MAIN
AVIATION CONCERN AT KFWA THROUGH THE EARLY EVENING WITH LIMITED
VIS/CEILING REDUCTION SEEN IN PRECIP SO FAR. DETERIORATING
CONDITIONS EXPECTED LATER TONIGHT AT BOTH TERMINALS AS COLD FRONT
APPROACHES THE AREA. WILL HOLD ABOVE FUEL ALTERNATE FOR NOW BUT A
BRIEF PERIOD OF LOW END MVFR CONDITIONS ARE POSSIBLE BY EARLY
TUESDAY MORNING. QUICK IMPROVEMENT TO VFR CATEGORY EXPECTED BY
LATE TUESDAY MORNING AS DRY SLOT OVERSPREADS THE REGION.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EDT WEDNESDAY FOR LMZ043-046.

&&

$$

UPDATE...AGD
SYNOPSIS...STEINWEDEL/LASHLEY
SHORT TERM...LASHLEY
LONG TERM...FISHER
AVIATION...AGD


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