Special Marine Warning 99, NWS Buffalo, NY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
546 PM EDT TUE SEP 10 2002

HAVE THROWN OUT A QUICK UPDATE TO ADJUST THE FIRST PERIOD PRECIP
FORECAST FOR THE NORTH COUNTRY. LATEST KTYX AND KBUF RADAR LOOPS ARE
SHOWING THAT THE THUNDERSTORM ACTIVITY JUST NORTH OF LAKE ONTARIO IS
ON A TRACK TO CLIP NORTHERN JEFFERSON/LEWIS COUNTIES AFTER 8 PM THIS
EVENING...PLUS ITS BEGINNING TO EXPAND TO THE SOUTH A BIT. THIS IS
CONSISTENT WITH CURRENT LAPS ANALYSES...WHICH SHOW A BULLSEYE OF
FAIRLY STRONG MOISTURE CONVERGENCE JUST AHEAD OF THE STORMS/OVER
NORTHERN LAKE ONTARIO. WITH THESE FACTORS IN MIND...THE CURRENT
WORDING OF CHC TRW FOR LATE EVENING LOOKS A LITTLE SLOW...SO I HAVE
REMOVED THE LATE QUALIFIER FOR OUR NORTHERNMOST ZONES.

NO OTHER CHANGES HAVE BEEN MADE TO THE GOING PACKAGE AS OF THIS TIME.

THIS AFTERNOONS DISCUSSION FOLLOWS....

JJR

********************* PREVIOUS DISCUSSION ***************************

COLD FRONT PUSHING EAST ACROSS NORTHERN LOWER MICHIGAN AT THE MOMENT
WITH THUNDERSTORMS DEVELOPING MAINLY NEAR AND NORTH OF SAGINAW BAY
TO EAST OF GEORGIAN BAY WHERE THE SURFACE CONVERGENCE IS GOOD BASED
ON OBSERVATIONS.  CONVERGENCE MUCH LESS OVER SOUTHERN LOWER MICHIGAN
AND FAR SOUTHWEST ONTARIO AND LITTLE SHOWER DEVELOPMENT HAS TAKEN
PLACE THERE...YET.  ALL OF THE SHORT-TERM MODELS AGREE ON PUSH OF
COLD FRONT THROUGH WESTERN AND CENTRAL NEW YORK IN ABOUT THE 04Z TO
09Z TIME FRAME FROM WEST-TO-EAST...WITH GOOD LIFT IN WESTERN NEW
YORK BETWEEN 03Z AND 06Z AND AROUND AND JUST AFTER 06Z TOWARD OSWEGO
AND LOWVILLE.  STRONG UPPER DIVERGENCE IS FORECAST THIS EVENING IN
THE LEFT EXIT REGION OF A 60KT JET AT 500MB.  THE BEST LIFTED
INDICES ARE FORECAST OVER ONTARIO AND PARTS OF MICHIGAN LATE THIS
AFTERNOON...FALLING TO MINUS 5...INCREASING TO MINUS 1 DEG C OVER
WESTERN NEW YORK LATE THIS EVENING.  CAPE NOT FORECAST TO BE TOO
IMPRESSIVE...BUT STILL EXPECT SOME GUSTY WINDS ASSOCIATED WITH THE
FRONTAL PASSAGE AND ANY THUNDERSTORMS DUE TO STRENGTH OF THE FRONT
AND MID-LEVEL VORT MAX.  SPC MOVED SLIGHT RISK OF SEVERE INTO BUF
CWFA FOR THE OVERNIGHT HOURS...AND THOUGH THINK THE CHANCES FOR
SEVERE ARE LIMITED BASED ON THE TIME OF DAY OF THE SYSTEM MOVING
THROUGH...WOULD NOT BE SURPRISED TO SEE WIND GUSTS EXCEED 40 MPH
WITH FRONTAL PASSAGE.

TIGHT GRADIENT USHERING IN MUCH COOLER AIR FROM THE NORTH...WITH
850MB TEMPERATURES FALLING TO 2C TO 4C ON BOTH THE NGM AND AVN BY
LATE WEDNESDAY AFTERNOON...SHOULD LIMIT TEMPERATURE RISES FOR THE
DAY WEDNESDAY.  ETA 850MB TEMPERATURES ARE A LITTLE WARMER...4C TO
6C BY WEDNESDAY AFTERNOON.  LAKE/850MB DELTA-T WILL PUSH 20C
WEDNESDAY AFTERNOON...BUT THE 1000-850MB MEAN WIND IS FORECAST TO BE
NEARLY DUE NORTH...LIMITING THE FETCH ACROSS THE LAKES.  MODEL
SOUNDINGS BECOME FAIRLY DRY PRETTY QUICKLY ON WEDNESDAY...BOTH OF
WHICH SHOULD LIMIT THE CHANCES FOR LINGERING SHOWERS BEYOND THE
MORNING HOURS.  WILL CONTINUE TO KEEP CLOUDS IN THE FORECAST THROUGH
WEDNESDAY EVENING...WITH SLOWLY WARMING 850MB TEMPERATURES AND
BACKING MEAN 1000-850MB WINDS RESULTING IN AT LEAST PARTLY CLOUDY
CONDITIONS BY SUNRISE THURSDAY.  AT THIS POINT...DO NOT PLAN TO
MENTION ANY FROST FOR SOUTHERN TIER VALLEYS LATE WEDNESDAY NIGHT...
BUT A FEW OF THE USUAL COOL SPOTS COULD SEE TEMPERATURES FALL INTO
THE 30S VERY LATE WEDNESDAY NIGHT ESPECIALLY IF THE WINDS CAN CALM
DOWN ENOUGH AND CLOUDS DIMINISH.

HIGH PRESSURE PREVAILS THROUGH THE END OF THE WORK WEEK AFTER THE
LOW PRESSURE SYSTEM MOVES OFF THE EAST COAST BY LATE IN THE DAY
WEDNESDAY.  THE AVN...AS WELL AS THE ETA...FORECAST A COLD FRONT TO
MOVE INTO SOUTHERN PARTS OF ONTARIO AND QUEBEC FRIDAY...BUT STRONG
HIGH PRESSURE CENTERED JUST TO OUR SOUTH SHOULD KEEP PRECIPITATION
AT BAY WITH THE DEEPER MOISTURE FORECAST TO REMAIN JUST NORTH AND
NORTHEAST OF JEFFERSON COUNTY.  QPF AND RIBBON OF HIGH MEAN RH ON
BOTH THE AVN AND ETA STAY ALONG AND JUST NORTH OF THE EAST/WEST PART
OF THE NORTHERN NEW YORK BORDER FRIDAY.  THE AVN MODEL HOLDS THE
NEXT COLD FRONT WELL TO OUR WEST SATURDAY...AND THE MRF IS SLOWER
WITH THE APPROACH OF THE FRONT WITH THE MOST RECENT RUN THAN WAS
FORECAST ON THE 09/00Z RUN OF THAT MODEL.  BY SUNDAY EVENING...THE
MRF HAS THE FRONT JUST APPROACHING EASTERN LAKE ERIE AND WESTERN
LAKE ONTARIO.  THE UKMET IS A LITTLE FASTER THAN THE MRF...BUT EVEN
THE OLD RUN OF THE ECMWF KEEPS THE FRONT FROM MOVING INTO WESTERN
NEW YORK UNTIL SUNDAY.  PLAN TO REMOVE THE CHANCE OF RAIN FOR
SATURDAY...BUT WILL KEEP THE THREAT OF RAIN IN FOR SUNDAY AND MONDAY
AT PRESENT...ESPECIALLY SINCE THE NEW AVN HAS THE FRONT ON OUR
DOORSTEP AT 12Z SUNDAY.  NEXT SHOT OF COOL AIR FOR MONDAY MAY BE
EVEN COOLER THAN WHAT WILL TRANSPIRE WEDNESDAY...THOUGH BASIC EXTRAP
BEYOND THE END OF THE AVN RUN MAY PUSH THE COOLEST THICKNESSES
TOWARD MAINE.

.BUF...NONE.

DJF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO, NY
1006 PM EDT TUE SEP 10 2002

TIME(EDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0855 PM    SANBORN                   NY   WIND DAMAGE
09/10/02   NIAGARA                        LARGE TREE DOWN REPORTED
                                          BY AMATEUR RADIO

0925 PM    MEDINA                    NY   WIND DAMAGE
09/10/02   ORLEANS                        LARGE TREE LIMBS DOWN
                                          REPORTED BY LAW ENFORCEMENT

SAGE