Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
1056 am EDT Tuesday Jul 7 2015
a very warm and muggy airmass will remain in place
today...until a cold front with showers and thunderstorms passes
across the region late afternoon and evening. Some of these storms
could become strong to severe with torrential downpours and gusty
winds. Behind the cold front...Wednesday will dry out with a return
to sunshine through the day and noticeably cooler dewpoints.
Near term /through tonight/...
a southwest wind will develop today ahead of the cold front to our
west. With the wind direction today off Lake Erie/Ontario...areas
along the shoreline and metropolitan Buffalo/Watertown will be slightly
cooler than yesterday as lake breeze circulations develop...while
areas across the Genesee Valley and Finger Lakes region may be a few
degrees warmer with a downslope flow into the valleys. This
downslope flow may even bring a few lower 90s to the Genesee Valley.
In general highs this afternoon should reach into the 80s...cooler
near lake shorelines and the hills of SW New York state.
This heat ahead of the cold front will rapidly destabilize the
atmosphere today. By around 21z...most unstable boundary layer cape
values will rise to 1000 to 2000 j/kg across the western southern
tier and Tug Hill region which should be enough to overcome the weak
lapse rates aloft. High precipitable water values in excess of 2
inches indicate heavy rain potential in any stronger shower or
Behind the cold front a few patches of fog are possible as falling
temperatures will cool to near the dewpoints. Expect clouds to
remain abundant overnight with lows dropping back to the low to middle
Short term /Wednesday through Thursday night/...
progressive Post-frontal drying will occur Wednesday from northwest
to southeast. This will result in a period of dry and stable
conditions Wednesday and Wednesday evening as high pressure builds
across the region. Highs Wednesday of lower to middle 70s with
noticeably lower humidity compared to today.
Middle level flow transitions to lower amplitude southwesterlies
immediately upstream of expanding subtropical ridging taking hold
over the southeast Continental U.S.. this evolution will potentially result in
a periodically active period through the latter half of the short
term period. This process will initiate late Wednesday night and
Thursday as a lead wave ejects out of the growing upper height field
across the southern Continental U.S.. respectable surface wave appears to
emerge with this feature...resulting in a compact but strong
corridor of forcing and accompanying moisture transport that shifts
into the Ohio Valley/Great Lakes during this time. Exact timing and
positioning remains somewhat ill-defined yet...potential exists for
at least southern portions of western New York to get into the
eventual precipitation swath. This continues to warrant a broader
and more conservative distribution of precipitation chances at this
stage with still a good deal of model spread remaining. The
extensive higher cloud cover and northerly low level gradient will
cap highs in the 70s Thursday...regardless of precipitation
Thursday night this surface wave will exit into New England with
rain chances diminishing from west to east.
Long term /Friday through Monday/...
Friday and Saturday a bubble of high pressure will stall in place
over the lower lakes and New England while a stalled frontal zone
remains to the west across the lower Ohio Valley and western lakes.
This should bring dry weather both days with temperatures slowly
warming back to just about average after a few cooler days midweek.
This will translate into highs in the lower 80s across lower
Sunday into early next week a middle level trough will move from the
upper Midwest into the western lakes. This will force increasing
moisture and instability back into our region...with large scale
forcing increasing by Monday as the middle level wave and weak surface
reflection move towards the lower lakes. This will bring a chance of
showers and storms again from later Sunday through Monday.
Temperatures will remain warm Sunday and Monday as long as showers
dont become too widespread...with highs in the lower 80s both days.
Humidity will be on the increase as well.
Aviation /15z Tuesday through Saturday/...
at 12z mainly VFR flight
conditions were found across the region.
Through the morning to middle afternoon hours expect VFR flight
conditions to be predominate. A few diurnally driven showers and
thunderstorms will be possible across the Genesee Valley/Finger
Lakes region with activity drifting northeastward. Later in the day
a few thunderstorms may Blossom across western New York...this on a
lake breeze boundary. This activity may near the kjhw/kroc
The larger concern this taf period will be a convective line of
showers and gusty thunderstorms passing across the taf sites. A cold
front will develop a line of storms...with activity nearing far wny
around 00z...and then pushing eastward across the taf sites between
00z and 06z. Expect a thunderstorm this evening with perhaps a
strong gust of wind...to be followed by trailing showers and areas
of low fog developing where rain has fallen. Some MVFR/IFR visibilities
will be likely for a few hours behind the cold front before drier
air arrives towards daybreak...allowing for improving flight
Wednesday...VFR. Thursday...mainly VFR with a chance
of showers and thunderstorms. Friday and Saturday...VFR.
on the lake waters southwesterly winds will freshen to
around 15kts today ahead of the cold front...however conditions
should remain below small craft levels on Tuesday.
The cold front will cross the lakes Tuesday evening...potentially
generating a squall line with a short period of stronger winds as it
crosses the lakes. Winds will quickly slacken behind the front as
weak high pressure moves across the region and lingers through the
rest of the week.