FXUS63 KIND 220328
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1027 PM EST MON DEC 21 2009
.UPDATE...
SATELLITE SHOWING A RELATIVELY IMPRESSIVE UPPER WAVE MOVING THROUGH
IOWA AT THE MOMENT. NEAR THE WAVE SNOW WAS SPREADING ACROSS IOWA.
LOCAL RADARS SHOWING INCREASING VIRGA ACROSS ILLINOIS AHEAD OF THE
SYSTEM...AND INCREASING RETURNS ACROSS NORTHERN MISSOURI AS WELL.
LATEST NAM/RUC MODELS SHOWING THAT AREA OF BEST FORCING WILL BE
FARTHER SOUTH THAN PREVIOUSLY THOUGHT. THE MODELS THUS BRING IN MORE
SNOW TO THE AREA...ESPECIALLY ACROSS NORTHWESTERN SECTIONS. THEY
ALSO BRING IN SOME FRONTOGENETICAL FORCING WITH THE WAVE. GIVEN THE
OBSERVED STRENGTH OF THE WAVE AND SOME SNOW ALREADY BREAKING OUT
ACROSS MISSOURI...FEEL THAT HIGHER POPS ARE WARRANTED ACROSS PARTS
OF THE FORECAST AREA. WENT LIKELY POPS IN THE LAFAYETTE AND KOKOMO
AREAS WITH CHANCE POPS DOWN TO NEAR THE BLOOMINGTON AND COLUMBUS
AREAS.
HIGHEST ACCUMULATIONS WILL MOST LIKELY BE NORTH OF THE FORECAST
AREA...BUT DID GO UP TO AN INCH ACROSS THE NORTHWEST FORECAST AREA.
LITTLE CHANGE TO REMAINDER OF FORECAST AS IT WAS ON TRACK.
THANKS TO NEARBY OFFICES FOR THE COLLABORATION THIS EVENING.
&&
.AVIATION...DISCUSSION FOR 22/00Z TAFS.
MVFR CIGS WILL CONTINUE ACROSS CENTRAL INDIANA TONIGHT...ALTHOUGH
THERE COULD BE A LITTLE IMPROVEMENT AT KHUF AND KBMG LATER TONIGHT
AS SOME DRYING OCCURS ALOFT WHICH WOULD MAKE THE CLOUD LAYER A
LITTLE THINNER. WEAK RIDGE OF HIGH PRESSURE ACROSS INDIANA WILL
CONTINUE TO MOVE EASTWARD AND LIGHT EAST TO SOUTHEAST FLOW WILL
DEVELOP LATER TONIGHT.
AN UPPER LEVEL WEATHER DISTURBANCE MAY BRING A FEW LIGHT SNOW
SHOWERS OVER NORTHERN AND CENTRAL SECTIONS LATE TONIGHT. THIS
COMBINED WITH LIGHT FOG SHOULD PRODUCE VISIBILITIES IN THE MVFR
CATEGORY. AS SE FLOW INCREASES ON TUESDAY...CIGS SHOULD LIFT TO 25
HUNDRED FEET MOST AREAS AND POSSIBLY EVEN BETTER AT KHUF AND KBMG.
&&
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...
LONG WAVE PATTERN EXPECTED TO REMAIN PROGRESSIVE OVER THE NEXT FEW
DAYS. RIDGING CURRENTLY OVER THE ROCKIES EXPECTED TO PUSH EASTWARD
INTO THE APPALACHIAN MOUNTAIN REGION BY THURSDAY...WITH THE NEXT
STORM SYSTEM EXPECTED TO BE LOCATED IN THE SOUTHERN PLAINS BY THAT
TIME. MODELS IN FAIRLY GOOD AGREEMENT ON THE MAIN FEATURES. FORECAST
FOCUS CENTERS ON POPS AND PRECIPITATION TYPE OVER THE NEXT COUPLE OF
DAYS.
MODEL DATA CONTINUE TO INDICATE AN AREA OF MID LEVEL FORCING ALONG
WITH NEAR SATURATION IN THE PRECIPITATION BEARING LAYERS OVER THE
NORTHERN SECTIONS OF THE FORECAST AREA DEVELOPING LATER TONIGHT AND
INTO TUESDAY. SNOW CURRENTLY BREAKING OUT ACROSS SOUTH DAKOTA AND
IOWA PROBABLY RELATED TO THIS. WILL KEEP CHANCE POPS GOING FOR LIGHT
SNOW OVER ABOUT THE NORTHEAST TWO THIRDS OF THE AREA FOR LATE
TONIGHT INTO TUESDAY AFTERNOON. POTENTIAL MAXIMUM SNOWFALL AMOUNTS
WITH THIS SYSTEM LOOK TO BE QUITE LIGHT...AROUND 1/2 INCH OR SO.
ATTENTION THEN TURNS TO THE SYSTEM THAT WILL BE AFFECTING THE LOCAL
AREA OVER THE SECOND HALF OF THE WEEK. OPERATIONAL MODELS ALONG WITH
THE ENSEMBLES CONVERGING ON PLACEMENT OF SURFACE LOW...IN THE
VICINITY OF SOUTHWEST MISSOURI AND SOUTHEAST KANSAS BY THURSDAY
MORNING. THE PRESENCE OF THE UPPER RIDGE AND A LARGE SURFACE HIGH
EXPECTED TO BE OVER THE NORTHERN GREAT LAKES FUNNELING DRY AIR INTO
THE SYSTEM SUGGESTS PRECIPITATION MAY HAVE A HARD TIME GETTING INTO
THE LOCAL AREA THROUGH WEDNESDAY NIGHT...BUT ALSO SUGGESTS
EVAPORATIVE COOLING PROCESSES MAY COME INTO PLAY REGARDING EVENTUAL
PRECIPITATION TYPE. AS A RESULT...PLANNING ON CHANCE POPS IN THE
SOUTHWEST FOR LATE TUESDAY NIGHT...AND CHANCE POPS ALL ARES
WEDNESDAY AND WEDNESDAY NIGHT. CRITICAL THICKNESSES SUGGEST MAINLY A
LIQUID OR FREEZING EVENT WITH LITTLE CHANCES OF SIGNIFICANT
SNOWFALL. AT THIS TIME...BEST CHANCES FOR FREEZING RAIN APPEAR TO BE
ALONG AND NORTHEAST OF INTERSTATE 74. BASED ON THE ABOVE
REASONING...EXPECTING ANY PRECIPITATION THAT OCCURS WILL BE RATHER
LIGHT. NO HEADLINES PLANNED AT THIS TIME.
DON/T HAVE A MAJOR PROBLEM WITH THE GFS MOS TEMPS BASED ON LOW LEVEL
THICKNESSES...ALTHOUGH BY WEDNESDAY THE GUIDANCE MAY BE SEVERAL
DEGREES TOO WARM. WILL NUDGE DOWN THE NUMBERS IN THAT
PERIOD.
&&
.LONG TERM...THURSDAY THROUGH MONDAY...
MODEL CONSENSUS IS COMING INTO LINE ON THE LOW PRESSURE OCCLUDING
SOMEWHERE OVER NORTHERN MISSOURI OR SOUTHERN IOWA BY THURSDAY
NIGHT...WITH A SLOW NORTHEASTWARD PROGRESSION TO THE LOW THEREAFTER
AS STRONG HIGH PRESSURE REMAINS IN THE WAY NORTH OF THE GREAT LAKES.
TRACK DIFFERENCES HAVE BECOME RELATIVELY MINOR AT THIS POINT...AT
LEAST WITH RESPECT TO PRECIPITATION TYPE OVER CENTRAL INDIANA. HAVE
TAKEN A BLEND OF THE 12Z ECMWF AND GFS ENSEMBLE MEAN FOR THE TIME
PERIOD.
AM STILL A BIT CONCERNED THAT SURFACE TEMPERATURES MAY BE AT OR JUST
BELOW 32F AT DAYBREAK THURSDAY...ESPECIALLY NORTHEAST OF INTERSTATE
74. WILL THEREFORE ALLOW FOR A CONTINUATION FOR A CHANCE OF FREEZING
RAIN TO START...GRADUALLY SHIFTING NORTH DURING THE MORNING.
EVALUATION OF LOW LEVEL THICKNESSES AND SURFACE TEMPERATURES
SUGGESTING PRECIPITATION SHOULD BE FALLING AS RAIN ACROSS THE ENTIRE
FORECAST AREA BY MIDDAY THURSDAY OR SHORTLY THEREAFTER. HAVE SLOWED
DOWN LIKELY POPS TO THURSDAY AFTERNOON AND NIGHT AS DEEPER FORCING
ARRIVES AHEAD OF THE FRONTAL BOUNDARY. 50-60KT 850 LOW LEVEL JET
SHOULD SERVE TO ENHANCE RAINFALL CONVERGE AND INTENSITY...WITH
POTENTIAL FOR A SOLID 1 TO 1.50 INCHES ACROSS THE REGION. THIS COULD
LEAD TO SOME LOCALIZED FLOODING ISSUES...ESPECIALLY ALONG THE
STREAMS IN THE SOUTHERN FORECAST AREA WHICH HAVE BEEN RUNNING HIGHER
DUE TO RAIN LAST WEEK. WILL CONTINUE TO MONITOR THIS POTENTIAL OVER
THE NEXT FEW DAYS.
IN WAKE OF THE FRONTAL BOUNDARY FRIDAY MORNING...TEMPERATURES MAY
SLOWLY FALL THROUGH THE DAY AS COLDER AIR SPREADS BACK INTO CENTRAL
INDIANA. DRY SLOT ON BACK SIDE OF THE BOUNDARY MAY ACTUALLY ALLOW
FOR A PERIOD WITH NO PRECIPITATION DURING THE DAY FRIDAY.
PRECIPITATION WILL RETURN AS COLD POOL OVERSPREADS THE AREA DURING
THE AFTERNOON...EITHER AS SNOW SHOWERS OR AS A SNOW/RAIN MIX BEFORE
CHANGING TO SNOW. THEN AS THE LOW DRIFTS NORTHEAST ACROSS THE GREAT
LAKES THROUGH THE WEEKEND...ANTICIPATE SCATTERED SNOW SHOWERS ACROSS
CENTRAL INDIANA THROUGH SUNDAY. MODEL SOUNDINGS SHOWING PLENTY OF
LOW LEVEL MOISTURE AND INCREASING COLD ADVECTION SATURDAY AND
SUNDAY...ALONG WITH SHALLOW LOW LEVEL INSTABILITY. COULD SEE MINOR
ACCUMULATIONS OVER THE WEEKEND...AND WILL ADDRESS IN GREATER DETAIL
AS WE GET CLOSER. TEMPERATURES WARMING INTO THE 40S...POSSIBLY EVEN
LOWER 50S ON THURSDAY IN THE WARM SECTOR WILL BEGIN SLIDING BACK ON
FRIDAY...EVENTUALLY SETTLING IN THE MID AND UPPER 20S OVER THE
WEEKEND. LOWS WILL FALL BACK INTO THE TEENS FOR SATURDAY/SUNDAY/
MONDAY MORNINGS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...CS
SHORT TERM...JAS
LONG TERM...RYAN
AVIATION...JH
