Special Marine Warning 64, NWS Buffalo, NY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
252 PM EDT MON JUL 8 2002

HIGHEST INSTABILITY IN THE FORECAST AREA CURRENTLY OVER AREAS EAST
OF WATERTOWN AND LOWVILLE...WHERE DEW POINTS IN THE MID 60S COMBINED
WITH SOME UPSLOPE HAVE RESULTED IN ISOLATED SHOWERS IN HIGHER
ELEVATIONS.  MAY HAVE TO CARRY AN ISOLATED SHOWER FOR THE EVENING
EAST OF LAKE ONTARIO...BUT ELSEWHERE CONDITIONS SHOULD REMAIN DRY
WITH DEW POINTS ONLY IN THE MID AND UPPER 50S WEST AND SOUTHWEST OF
ROCHESTER.

MOISTURE WILL INCREASE OVERALL ACROSS WESTERN AND CENTRAL NEW YORK
OVERNIGHT.  SOME OF THE HIGHER DEW POINTS TO THE WEST WILL BEGIN TO
ADVECT INTO THE AREA...ESPECIALLY AFTER 06Z IN THE FAR SOUTHWEST
ZONES...BRINGING DEW POINTS AT LEAST INTO THE MID 60S BY DAWN
THROUGHOUT WESTERN AND CENTRAL NEW YORK.  MODELS ALL AGREE WITH THE
BASIC SCENARIO OF A COMPLEX OVER THE NORTHERN GREAT LAKES SWOOPING
SOUTHEAST ACROSS WESTERN NEW YORK BETWEEN 09Z AND 13Z.  WITH THE
MODELS...THERE ARE BIG DIFFERENCES IN QPF.  THE NGM SHOWS A TENTH OR
LESS...THE ETA IS BETWEEN 0.25 AND 0.50...AND THE AVN PROVIDES FOR
1.5 INCHES OR MORE IN SPOTS THROUGH THE DAY TUESDAY.  LOOKING AT THE
DETAILS...BOTH THE NGM AND ETA HAVE MUCH LESS OF A 850MB LOW-LEVEL
JET OVER WESTERN AND CENTRAL NEW YORK OVERNIGHT...WHILE THE AVN
SUPPORTS A DECENT LOW-LEVEL JET FROM NORTHERN OHIO INTO WESTERN NEW
YORK BY SUNRISE.  NOT BEING ONE TO FOLLOW BIG BULLSEYES...WILL LEAN
TOWARD THE ETA SOLUTION ON AVERAGE...THOUGH BOTH THE AVN AND ETA
SHOW A WEAK WAVE ALONG THE SURFACE FRONT MOVING INTO WESTERN NEW
YORK TOWARD SUNRISE WHICH COULD PROVIDE FOR ISOLATED HEAVY AMOUNTS
OF RAIN ESPECIALLY WITH A FLOW ALOFT THAT IS NOT VERY STRONG.

EAST OF LAKE ONTARIO OVERNIGHT...SOME OF THE PRECIPITATION FROM
CANADA WILL SKIRT THE AREA.  LOOP OF THE LATEST RADAR DATA SHOWS
MOST OF THE PRECIPITATION SHOULD STAY NORTH OF JEFFERSON COUNTY THIS
EVENING...AND WITH THE EMPHASIS OF LIFT AND INSTABILITY FARTHER
SOUTHWEST LATE TONIGHT AS ELEVATED LIS FROM 900MB FALL TO -1 OR -2
IN FAR WESTERN ZONES...WILL LEAN TOWARD HIGH CHANCE POPS.  MODELS
SHOW THE HIGHEST 850MB THETA-E AIR OVER THAT AREA DURING THE EARLY
EVENING HOURS...WITH A RELATIVE MIN MOVING NORTHEAST FROM NORTHEAST
OHIO AND FAR WESTERN NEW YORK.  MID-LEVEL VORTICITY IS ALSO PROGGED
TO STAY NORTH OF JEFFERSON AND LEWIS COUNTIES OVERNIGHT.

WAVE ALONG THE COLD FRONT MOVES THROUGH WESTERN AND CENTRAL NEW YORK
DURING TUESDAY MORNING...BUT WITHOUT A STRONG PUSH BEHIND THE FRONT
FOR THE DAY TUESDAY...THINK THE AIR MASS MAY RECOVER ENOUGH IN THE
AFTERNOON TO AT LEAST WARRANT A CONTINUED CHANCE OF THUNDERSTORMS
THROUGH THE AFTERNOON...AND INTO THE VERY EARLY EVENING MAINLY JUST
OVER THE SOUTHERN TIER.  MODEL SOUNDINGS SHOW CAPE INCREASING TO
AROUND 1500 J/KG IN THE AFTERNOON WITH DEW POINTS REMAINING AT LEAST
IN THE MID 60S.  K INDICES ARE IN THE MID 30S...AND AS THE MAIN
FRONT PUSHES THROUGH...THERE MAY BE ENOUGH LIFT TO SUPPORT SCATTERED
THUNDERSTORMS ALONG THE FRONT.  DIMINISHING SHEAR MAY KEEP MUCH FROM
HAPPENING...BUT THE MODEL SOUNDINGS ARE PRETTY UNSTABLE IN THE
AFTERNOON TUESDAY.  SEVERE WEATHER AN OUTSIDE POSSIBILITY...MORE IN
THE AFTERNOON THAN IN THE MORNING AND PROBABLY ISOLATED AND MARGINAL
DUE TO RELATIVELY LIGHT WINDS ALOFT AND HIGH FREEZING LEVELS.  DRIER
AIR MOVES INTO THE FORECAST AREA TUESDAY EVENING.  TENDED TO
FORECAST TEMPS NEAR THE HIGH END OF THE AVN...NGM...AND ETA
ESPECIALLY THROUGH TUESDAY EVENING.

UPPER LOW HANGS AROUND OVER THE CANADIAN MARITIMES THROUGH MID WEEK
AS THE SURFACE HIGH BUILDS IN.  MODEL SOUNDINGS SHOW ENOUGH
LOW-LEVEL MOISTURE AND COOL AIR ALOFT TO GIVE SOME AFTERNOON CU.
TEMPERATURES WILL BE SEASONABLY COOL BEFORE WARMING SOME AS THE
WEEKEND APPROACHES WITH INCREASING THICKNESSES AND A SHIFT TO A
LIGHT SOUTHERLY FLOW.

MRF...ECMWF...AND UKMET ARE ALL IN GOOD AGREEMENT WITH SURFACE HIGH
PRESSURE OVER WESTERN AND CENTRAL NEW YORK FOR MOST OF THE EXTENDED
PERIOD.  DRY CONDITIONS AND SEASONAL TEMPERATURES WILL BE THE RULE.
THE MRF IS FASTER WITH A DIGGING UPPER TROUGH OVER THE EASTERN GREAT
LAKES SUNDAY...BRINGING A WEAK COLD FRONT THROUGH THEN.  MOISTURE
WILL BE ON THE INCREASE LATE IN THE WEEKEND...BUT THE STRONG PVA
REMAINS NORTH OF THE AREA ON THE MRF AND THE DEGREE OF COLD AIR
ADVECTION DIMINISHES.  PLAN TO INCLUDE A CHANCE OF THUNDERSTORMS
SUNDAY...ANTICIPATING CONDITIONS IMPROVING MONDAY.  THE COLD FRONT
SHOULD BE EAST OF THE FORECAST AREA BY MONDAY MORNING...WITH HIGH
PRESSURE BUILDING IN AT THE SURFACE.  CORE OF THE UPPER LOW...IF THE
MRF VERIFIES...SHOULD BE FAR ENOUGH EAST MONDAY AFTERNOON TO KEEP
THE BETTER CHANCES OF DIURNAL SHOWERS OR THUNDERSTORMS JUST EAST OF
THE BUF CWFA.  THIS WILL HAVE TO BE WATCHED...THOUGH...AS THE NEW
AVN IS JUST A TOUCH SLOWER ON THE TIMING THAN THE 00Z MRF.

.BUF...NONE.

DJF