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Area Forecast Discussion

000
FXUS63 KIWX 180958
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
558 AM EDT FRI APR 18 2014

.SYNOPSIS...
ISSUED AT 400 AM EDT FRI APR 18 2014

A WEAK COLD FRONT WILL PASS THROUGH THE AREA THIS MORNING WITH A
SLIGHT CHANCE OF SHOWERS. HIGH PRESSURE AND DRY CONDITIONS WILL
THEN RETURN BY THE AFTERNOON. THIS HIGH PRESSURE SYSTEM WILL BRING
MOSTLY CLEAR SKIES FOR MUCH OF THE WEEKEND.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM EDT FRI APR 18 2014

WEAK COLD FRONT CURRENTLY CROSSING THE AREA WITH VERY LITTLE 
FANFARE. IN FACT...NOT MUCH EVIDENCE OF A SURFACE FRONT AT ALL IN 
LATEST TEMP/PRESSURE/WIND REPORTS. BETTER EVIDENCE OF FRONTAL 
FEATURE RESIDES AROUND 850MB WITH INCREASED BAROCLINICITY AND 
CONVERGENCE SEEN THERE. IT IS WITHIN THIS ELEVATED REGION OF WEAK 
BUT SUBTLY INCREASING FRONTOGENESIS THAT OUR CHANCES OF PRECIP 
REMAIN. REGIONAL REFLECTIVITIES HAVE GRADUALLY INCREASED IN THE PAST 
FEW HOURS AS EXPECTED. THIS IS IN RESPONSE TO SHORTWAVE TROUGH OVER 
THE UPPER MIDWEST FINALLY APPROACHING THE REGION. UPPER LEVEL FLOW 
CONFIGURATION ASSOCIATED WITH THIS WAVE AND THE TROUGH MOVING 
THROUGH THE GULF COAST STATES HAS ALSO LEFT THE SOUTHERN GREAT LAKES 
IN A FAVORABLE POSITION WITH RESPECT TO CORRESPONDING JET STREAKS. 
ASSOCIATED UPTICK IN LOW LEVEL FGEN AND DIVERGENCE ALOFT HAS ALLOWED 
SHOWERS TO INCREASE BUT DRY AIR BELOW 6 KFT...AS SEEN ON 00Z KILX 
SOUNDING...IS STILL TAKING ITS TOLL AMID ONLY MODEST FORCING. ONLY 
TRACE REPORTS SEEN SO FAR. MORE IMPORTANT ASPECT TO NOTE FOR TODAY'S 
FORECAST IS THE TRANSIENT NATURE OF AFOREMENTIONED JET STREAKS. 
POSITIONING FAVORABLE TO OUR CWA WILL ONLY LAST A SHORT TIME THIS 
MORNING WITH LEFT ENTRANCE FRONTOLYSIS NOTED BY MIDDAY. THIS 
SUGGESTS A GRADUAL DECREASE IN ALREADY HANDICAPPED PRECIPITATION 
EFFICIENCY THROUGH THE REST OF THE MORNING. LATEST HI-RES/RAPID 
UPDATE MODELS REFLECT THIS EXPECTATION WELL WITH LITTLE TO NO QPF 
AFTER ROUGHLY 13Z. WILL THEREFORE PARE BACK LATE MORNING POPS AND 
REMOVE ANY MENTION POST 18Z. THIS SHOULD ALLOW FOR FAIRLY PLEASANT 
AFTERNOON. WEAK CAA WILL SEND 925MB TEMPS TO AROUND 5C IN THE 
NORTHWEST BUT STILL HOLDING ABOVE 10C IN THE SOUTHEAST. MIXING 
DEPTHS APPEAR MUCH GREATER IN THE SOUTHEAST AS WELL BASED ON LATEST 
NAM AND GFS BUFR SOUNDINGS. THEREFORE EXPECT ANOTHER DAY OF MID TO 
UPPER 60S IN OUR SOUTHEAST BUT ONLY UPPER 50S AROUND KSBN. CLOUDS 
WILL ALSO DECREASE THROUGH THE DAY AND CLEAR SKIES WITH LIGHT 
NORTHEAST WINDS COULD ALLOW TEMPS TO DROP INTO THE LOW TO MID 30S 
FOR MANY AREAS TONIGHT. LOWERED INHERITED MINS JUST A TOUCH TO BE 
MORE IN LINE WITH CONSENSUS OF LATEST MOS AND RAW GUIDANCE BUT 
OVERALL CHANGES MINIMAL. 

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 400 AM EDT FRI APR 18 2014

ANOTHER MILD WEEKEND IN STORE FOR THE AREA WITH PCPN LIKELY
HOLDING OFF UNTIL MONDAY. HIGH PRESSURE WILL DRIFT ACROSS THE
LAKES THIS WEEKEND. SATURDAY WILL SEE SURFACE WINDS FROM THE EAST
TO SOUTHEAST. LOW LEVEL FLOW OFF THE EASTERN LAKES WILL LIKELY
KEEP FAR NORTHEAST CWA IN A COOL MARINE LAYER WITH TEMPS REMAINING
IN THE 50S. FULL SUN EXPECTED DURING THE DAY AND NAM12 SOUNDINGS
INDICATE MIXING TO ABOUT 900MB WHICH YIELDS TEMPS IN THE LOWER 60S
CENTRAL AND MID 60S SOUTHWEST. DRY ATMOSPHERE YESTERDAY ALLOWED
FOR A LARGE DIURNAL SWING WITH SUPERADIABATIC LAPSE RATES NEAR THE
SURFACE AND THINK THIS WILL BE POSSIBLE SATURDAY OUTSIDE OF
AFOREMENTIONED LAKE INFLUENCE.

HIGH PRESSURE WILL SLIDE EAST TO NEW ENGLAND ON SUNDAY ALLOWING FOR 
WARMER RETURN FLOW AND DEEPER MIXING HEIGHTS TO 850MB. MIXING TOOLS 
SUGGEST TEMPS COULD EASILY APPROACH MID 70S IF THESE PROFILES 
VERIFY. HAVE CONTINUED TREND OF BUMPING TEMPS UP AS CONFIDENCE 
INCREASES. MAY SEE SOME AFTERNOON CIRRUS DRIFT OVER AHEAD OF NEXT 
SYSTEM WHICH MAY IMPACT TEMPS A FEW DEGREES. 

NEXT SHORT WAVE MOVES THROUGH MONDAY AND MONDAY EVENING. DEEP 
MOISTURE IS LACKING BUT A LITTLE BETTER THAN CURRENT SYSTEM WHICH IS 
STRUGGLING TO PRODUCE MEASURABLE PCPN. GULF REMAINS CUT OFF BUT 
MODELS ARE A BIT STRONGER WITH DYNAMICS. GFS PLACES RIGHT ENTRANCE 
REGION OF MID LEVEL JET OVER THE GREAT LAKES WHICH WOULD AID LIFT. 
ECMWF NOT AS STRONG WITH THIS JET. KEPT THE ALLBLEND POPS IN THE MID 
CHANCE RANGE GIVEN THESE FACTORS. 

MID WEEK LOOKING COOLER IN WAKE OF THIS SHORT WAVE AND ASSOCIATED 
COLD FRONT. 00Z ECMWF CONTINUES TO TREND COOLER WITH 850MB TEMPS 
DROPPING TO -5C WEDNESDAY MORNING. MEX MOS HAS ALSO TRENDED COOLER 
WITH LOWS WEDNESDAY MORNING IN THE UPPER 30S...ABOUT 6 TO 8 DEGREES 
COOLER THAN 17/00Z RUN. HAVE LOWERED TEMPS WEDNESDAY SEVERAL DEGREES 
FROM ALLBLEND GIVEN THESE LATEST MODEL SOLUTIONS. 

ANOTHER HIGH WILL SLIDE THROUGH THE GREAT LAKES WEDNESDAY INTO 
THURSDAY. RETURN FLOW ONCE AGAIN DEVELOPS THURSDAY AS STRONG LOW 
PRESSURE STILL EXPECTED TO ORGANIZE IN PLAINS. THIS WILL HELP 
INCREASE LOW LEVEL JET AND ALLOW WARMER AIR TO SURGE NORTH. SHOULD 
SEE TEMPS REBOUND BACK INTO 60S AND LOWER 70S ON THURSDAY WITH A 
CHANCE FOR SHOWERS.      

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 558 AM EDT FRI APR 18 2014

LIGHT RAIN SHOWERS ASSOCIATED WITH WEAK COLD FRONT HAVE NOW EXITED
KSBN AND EXPECT KFWA TO REMAIN DRY GIVEN NORTHWARD DISPLACEMENT OF
BETTER JET FORCING. SLIGHT CHANCE OF SOME MVFR VISIBILITIES AT
KSBN RIGHT AROUND SUNRISE DUE TO CALM WIND AND ADDED SURFACE
MOISTURE FROM OVERNIGHT SPRINKLES BUT ANY REDUCTION WILL LIKELY BE
BRIEF AND MINOR. OTHERWISE VFR CONDITIONS EXPECTED THE REST OF THE
DAY AS HIGH PRESSURE BUILDS INTO THE REGION. CEILINGS AROUND KSBN
MAY HOVER AROUND 3 KFT AS DIURNAL CU RAMP UP THIS MORNING BUT
CLEARING SKIES EXPECTED AT BOTH TERMINALS BY AFTERNOON.

&&

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

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...LASHLEY
AVIATION...AGD

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