Possible Large Freezing Rain Event. PV down to 500mb!
Posted by JAC on 1/30/2011, 10:50 am
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
545 AM EST SUN JAN 30 2011

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...

MODELS ARE IN PRETTY GOOD AGREEMENT IN THE SHORT TERM AND WILL USE
A BLEND. MAIN FORECAST CHALLENGE THROUGH MONDAY WILL BE
TEMPERATURES...BUT THEN FOCUS WILL CHANGE TO THE MAJOR STORM
EXPECTED TO PUSH THROUGH THE AREA DURING THE MIDDLE PART OF THE
WEEK.

THE BROAD...COLD HIGH PRESSURE SYSTEM IS EXPECTED TO KEEP THE COLD
NORTHEAST FLOW ACROSS THE FORECAST AREA TONIGHT AND MONDAY. TIME
HEIGHT SECTIONS AND FORECAST SOUNDING SHOW GENERALLY A DRY COLUMN
WITH LITTLE IN THE WAY OF FORCING TONIGHT AND MONDAY. THUS AGAIN
EXPECT MOSTLY CLOUDY SKIES THROUGH MONDAY ALONG WITH HIGHS COOLER
THAN THE MAVMOS AND LOWS SLIGHTLY WARMER THAN MAVMOS.

THE STRONG STORM SYSTEM CURRENTLY APPROACHING THE WEST COAST OF
THE UNITED STATES WILL THEN BEGIN TO EFFECT THE AREA STARTING ON
MONDAY NIGHT AS THE GFS AND NAM SUGGEST A PRECURSOR TO THE MAJOR
WAVE THAT WILL PUSH THROUGH ON TUESDAY THROUGH WEDNESDAY. GFS 290K
ISENTROPIC SURFACE SHOWS STRONG LIFT ACROSS THE AREA AFTER 00Z
TUESDAY...WITH MIXING RATIOS NEAR 4 G/KG. FORECAST SOUNDINGS ARE
SATURATED AND BELOW ZERO ACROSS THE NORTHWEST...WHILE MUCH OF THE
REST OF CENTRAL INDIANA REVEALS A CLASSIC FREEZING RAIN TYPE
SOUNDING. THUS WILL RAISE POPS DURING THIS TIME FRAME...BUT LEAN
WARMER THAN MAVMOS ON LOWS GIVEN THE EXPECTED PRECIPITATION.

THE NEXT AND MORE POWERFUL PART OF THE STORM SYSTEM LOOKS TO
ARRIVE ACROSS THE AREA ON TUESDAY AND WILL CONTINUE TO LAST INTO
WEDNESDAY. AHEAD OF THE SYSTEM A STRONG SOUTHWEST TO NORTHEAST
THERMAL GRADIENT WILL BE IN PLACE ACROSS CENTRAL INDIANA. THE
NORTH SIDE OF THIS BOUNDARY...LAF...KOKOMO...WILL MAINLY BE SEE
SNOW AS FORECAST SOUNDINGS SHOWS THEIR PROFILES TO REMAIN BELOW
ZERO. MEANWHILE TO THE SOUTH...IND...HUF...MIE...BMG...FORECAST
SOUNDINGS CONTINUE TO SHOW A CLASSIC FREEZING RAIN SOUNDING. MANY
FORCING MECHANISMS WITH THIS SYSTEM. FIRST...UPPER JET SHOWS
COUPLING. 300MB HEIGHTS SHOW RIGHT REAR REGION ACROSS WISCONSIN
AND AN APPROACHING LEFT ENTRANCE ACROSS MISSOURI. THIS SHOULD
RESULT IN STRONG LIFT ACROSS ILLINOIS...POISED TO PUSH THROUGH
CENTRAL INDIANA. SECOND...VERY STRONG VORTICITY ADVECTION SEEN AT
500MB AS THE TROUGH APPROACHES AND PASSES ACROSS CENTRAL INDIANA.
THIRD...POTENTIAL VORTICITY ALSO SHOWS STRATOSPHERIC INTRUSION
DOWN TO NEARLY 450-500MB DEPENDING UPON YOUR MODEL CHOICE. THIS IS
INDICATIVE OF VERY STRONG FORCING. THIRD...VERY STRONG Q VECTOR
DIVERGENCE ALOFT ACROSS INDIANA ON TUESDAY NIGHT INTO WEDNESDAY.
FOURTH...THE 700MB CLOSED LOW IS EXPECTED TO PUSH ACROSS CENTRAL
AND NORTHERN INDIANA ON TUESDAY NIGHT INTO WEDNESDAY. TYPICALLY
THE HEAVIEST PRECIPITATION WILL FALL ALONG THE PATH OF A 700 MB
CLOSED LOW. FIFTH...THE GFS 290K ISENTROPIC SURFACE SHOWS VERY
STRONG UPGLIDE ESTABLISHING ITSELF ON TUESDAY AFTERNOON AND
LASTING UNTIL EARLY WEDNESDAY MORNING. PLENTY OF MOISTURE IS
AVAILABLE ALONG THIS SURFACE AS MIXING RATIOS REACH 5 TO 6 G/KG.
SIXTH...FORECAST SOUNDINGS SHOW A DEEPLY SATURATED COLUMN WITH
STRONG LIFT. SEVENTH...THE SURFACE LOW IS EXPECTED TO APPROACH
INDIANA FROM WESTERN TENNESSEE ON TUESDAY NIGHT...PUSHING
NORTHEAST ALONG THE OHIO RIVER ON TUESDAY NIGHT. AGAIN...THIS IS A
FAVORABLE TRACK FOR HEAVY SNOW ACROSS CENTRAL INDIANA.
HOWEVER...FORECAST SOUNDINGS CONTINUE TO INDICATE A VERY
STRONG...LOW LEVEL JET LATE ON TUESDAY NIGHT. GFS HINTS AT 70-80
KNTS ACROSS KENTUCKY AND SOUTHEAST INDIANA. THIS KIND OF WARM AND
MOIST TRANSPORT CERTAINLY WILL OVERRUN COLDER AIR...EXPECTED TO BE
IN THE 20S...AT THE SURFACE. GIVEN THIS...NAM POTENTIAL
TEMPERATURE SURFACE AT 650MB ALSO SUGGEST TROWAL DEVELOPMENT LATE
TUESDAY NIGHT. FINALLY...BUFKIT SHOWS WIND GUSTS TO NEAR 35 MPH IN
THE WAKE OF THE SYSTEM ON WEDNESDAY AFTERNOON. IF SIGNIFICANT
FREEZING RAIN DOES OCCUR...THESE WINDS IN COMBINATION WITH THAT
ICE WILL RESULT IN DOWNED TREES AND POWER LINES.

I REST MY CASE.

GIVEN THIS WILL ISSUE WINTER STORM WATCH FOR THIS TIME
FRAME...STARTING ON TUESDAY AFTERNOON AND CONTINUING THROUGH 00Z
THURSDAY. GIVEN WE ARE STILL A FEW DAYS OUT ON THIS
SYSTEM...PRECISE TRACKING OF THE STORM IS NOT YET
AVAILABLE...HOWEVER CONFIDENCE IS HIGH THAT A STRONG SYSTEM WILL
BE PUSHING THROUGH THE AREA DURING THIS TIME FRAME. SOME AREAS
WILL SEE HEAVY SNOW AND OTHERS WILL SEE SIGNIFICANT FREEZING RAIN
OR ICE. THE POTENTIAL EXISTS FOR A SIGNIFICANT SNOWFALL AND ICE
STORM DURING THE MIDDLE PART OF THE WEEK...WHICH COULD RESULT IN
VERY DIFFICULT TRAVEL CONDITION...HEAVY SNOW AND EVEN DOWNED TREES
AND POWER LINES. VERY COLD AIR IS EXPECTED IN THE WAKE OF THIS
SYSTEM AND A QUICK THAW IS NOT EXPECTED.

&&

50
In this thread:
Is it just me? - Conclue, 1/27/2011, 6:41 pm
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.