PREV DISCUSSION... /ISSUED 455 PM EST MON FEB 12 2007/
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
THE CALM BEFORE THE STORM ACRS FCST AREA THIS
AFTN. TEMPS HAD
WARMED INTO THE L/M30S ACRS MOST OF FCST AREA...PUSHING 40 DEG
ACRS NRN KY. VERY LIGHT PCPN (LARGELY IN THE FORM OF RAIN) WAS
FALLING ACRS MUCH OF CNTRL KY.
MAJOR WINTER STORM REMAINS FOCUS OF SHORT TERM.
MODELS CONTINUE TO
ALIGN...AND THE NORTHWARD SURGE TO THE WARMER BNDRY LYR AIR AND
TRACK OF THE
SFC LO ADVERTISED ON RUNS LAST NIGHT HAVE BEEN
SUPPRESSED
BACK SOUTH TODAY. 12Z
GFS IN FACT LOOKED AWFULLY
SIMILAR TO SUN
AFTN GFS WITH REGARDS TO ITS THERMAL PROFILE AND
PCPN TYPE. 12Z
NAM WAS SENDING THE 0 DEG ISOTHERM AT 850
MB ALL
THE WAY INTO WEST CNTRL OH ON TUES
AFTN. STILL BELIEVE THIS IS TOO
AGGRESSIVE OF A PUSH NORTHWARD WITH THE WARMER AIR CONSIDERING
STRONG NE
SFC LO. QUICK LOOK AT 18Z
NAM SUPPORTS THIS
THINKING...AS WARMER AIR SUPPRESSED SLIGHTLY FURTHER SOUTH. 12Z
GFS APPEARS TO BE MORE CONSISTENT WITH LO LVL THERMAL FIELDS AND
IS WELL SUPPORTED IN TERMS OF A MORE SRN
SFC LO TRACK THRU SRN
KY/NRN TN BY 12Z RUNS OF
GFS ENSEMBLES...
ECMWF AND
UKMET. HAVE
THUS TRENDED POTENTIAL PCPN TYPES AND DURATION MORE TOWARDS
CONSENSUS SOLN AND LESS TOWARDS
NAM WHICH AGAIN JUST SEEMS TOO
WARM. HAVE UPGRADED TO A WARNING ACRS ALL BUT FAR SNR FCST AREA
WHERE A WINTER
WX ADVISORY HAS BEEN ISSUED.
OTHER THAN SOME LIGHT PCPN...SHOULD BE RELATIVELY QUIET AT LEAST
INITIALLY THIS EVNG. LO LVL LIFT AND CONV REALLY GET GOING ACRS
SRN IN/OH AND NRN KY AFT MIDNIGHT WITH A MID LVL DEFORMATION/
FRONTOGENESIS AXIS SETTING UP. MODEL SOUNDINGS CONTINUE TO
GENERALLY SUPPORT ALL SNOW LATE TONIGHT EXCEPT NEAR AND SOUTH OF
THE OHIO RIVER WHERE FZRA AND IP ARE LIKELY TO MIX IN AS THE
WARMER BNDRY LYR AIR SURGES NORTH LATE. BY 12Z TUES...MIXED PCPN IS
EXPECTED ALONG AND SOUTH OF A CINCY METRO TO HILLSBORO AND PIKETON
LINE. FURTHER NORTH...PCPN WILL REMAIN SNOW.
SFC LO THEN TRACKS
ACRS SRN KY/NRN TN DURING THE DAY TUES WITH ABUNDANT GULF MOISTURE
BEING LIFTED INTO THE REGION COMBINED WITH DEEP MID LVL
DEFORMATION AND LIFT. SPLIT UPR
JET PLACING REGION IN RIGHT REAR
QUAD WILL FURTHER ENHANCE LO LVL CONV AND LIFT. THE AREA OF MIXED
PCPN WILL CONTINUE TO LIFT NORTH THRU THE DAY WITH BEST GUESS AS A
NORTHERN EDGE BEING AROUND OR JUST NORTH OF THE I-70 CORRIDOR.
NORTH OF HERE ACRS WEST CNTRL OH INTO AREAS NORTH OF CMH
METRO...HVY SNOW IS EXPECTED WITH MINIMAL OR NO SLEET MIXING IN.
AMOUNTS HERE WILL BE SIGNIFICANT WITH SNOW TO LIQUID RATIOS LIKELY
TO BE MORE ON THE ORDER OF 15 TO 1 AS OPPOSED TO 10 TO 1. AS
SFC
PRES GRADIENT TIGHTENS DURING THE
AFTN...N/NW WINDS WILL INCREASE
WITH GUSTS TO AROUND 30 MPH EXPECTED. THIS WILL ALLOW FOR A
SIGNIFICANT AMOUNT OF BLOWING AND DRIFTING OF SNOW TO TAKE
PLACE...WITH POTENTIAL FOR NEAR
BLIZZARD CONDITIONS AT
TIMES...ESPECIALLY ACRS WEST CNTRL OH.
SOUTH OF I-70...VARYING AMOUNTS OF MIXED PCPN ARE EXPECTED...WITH
POTENTIAL FOR EXTENDED PERIOD OF IP/FZRA FROM A BROOKVILLE IN-
WILMINGTON-LANCASTER LINE SOUTH INTO CINCY METRO. SIGNIFICANT
ICING IS EXPECTED IN THIS ZONE. FOR DAY/CMH METROS...MIXED PCPN IS
EXPECTED BUT SNOW WILL LIKELY REMAIN MORE DOMINANT PCPN TYPE. IP
AND FZRA MAY BE EXPERIENCED THROUGH THESE AREAS. SOUTH OF A
CINCY-CHILLICOTHE LINE...APPEARS ENUF WARM AIR WILL BE PULLED
NORTH TO ALLOW FOR
SFC TEMPS TO CLIMB ABV 32F AND THUS A PERIOD OF
RAIN TUES
AFTN/EVNG. AS
SFC LO SHIFTS EAST TUES NIGHT WITH ENERGY
TRANSFER INTO A COASTAL LO SOMETIME AFT MIDNIGHT TUES NIGHT...
COLDER AIR WILL RUSH
BACK INTO FCST AREA FROM NW DURING EVNG
HOURS. PCPN WILL CHANGE
BACK OVER TO ALL SNOW ACRS FCST AREA
SHORTLY AFT MIDNIGHT. WINDS WILL REMAIN STRONG TUES NIGHT ON
BACK
SIDE OF
SFC LO...WITH SUSTAINEDS NEAR 20 MPH AND GUSTS TO 30 MPH
AND GREATER. THIS WILL CONTINUE TO CAUSE BLOWING/DRIFTING OF SNOW
ACRS NRN FCST AREA. FURTHER SOUTH....SIGNIFICANT PROBLEMS ARE
EXPECTED WITH ANY ICE ACCUM ON TREES/POWER LINES. PCPN INTENSITY
SHOULD DECREASE DURING THE NIGHT AS DEEPER MOISTURE AND LIFT SHIFT
EAST OF REGION. HOWEVER...
MODELS INDCG MID LVL DEFORMATION AXIS
HANGS
BACK BEHIND
SFC LO ACRS FCST AREA THRU ERLY WED...ALLOWING
FOR SNOW TO LINGER FOR MUCH OF THE OVERNIGHT.
AS HAS BEEN STATED ALREADY...ANY SUBTLE SHIFT IN STORM TRACK WILL
HAVE A MAJOR IMPACT ON PCPN TYPE AND DURATION IN ANY ONE LOCATION.
BREAKDOWN ON SN/IP/FZRA ACCUMS THRU TUES NIGHT IS AS FOLLOWS...
10-14 INCHES OF SNOW ACRS WEST CNTRL OH...6-10 INCHES OF SNOW WITH
IP AND SOME FZRA ACCUM ACRS WHITEWATER/MIAMI VLYS INTO CMH
METRO...4-7 INCHES OF SNOW WITH SIGNIFICANT ICE ACCUMS IN A SWATH
FROM BROOKVILLE EAST THRU WILMINGTON AND CONTINUING NORTH INTO
AREAS SOUTHEAST OF CMH...2-4 INCHES OF SNOW/IP ACCUM WITH
SIGNIFICANT ICE ACCUMS FROM CVG METRO NE TOWARDS CHILLICOTHE.
FINALLY...ACRS FAR SRN FCST AREAS OF NRN KY AND SOUTH CNTRL
OH...LIGHT SNOW AND ICE ACCUMS ARE POSSIBLE WITH PERIOD OF RAIN
LIKELY AS WELL.
http://www.srh.noaa.gov/productview.php?pil=AFDILN
In essence, the models the forecasters use to come up with their forecasts have again shifted the track of the storm further to the south. That means that most of us along I-70 and to the north will see more snow. Those to the south of that, and along I-71 and to the east, may see more icing.
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