Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Binghamton New York
1059 am EDT Wednesday Aug 20 2014
a low pressure system moving slowly through the Great Lakes
region will bring the area showers and thunderstorms this afternoon
through Thursday. Locally heavy rain is possible through
Thursday, especially in New York state.
Near term /until 6 PM this evening/...
at 11 am...radar shows rain showers entering our western counties in The
Finger lakes in assctn with a well defined upper level wave as
seen on the water vapor imagery. This wave will work east this
afternoon and provide lift and just enough instability to lead to
numerous to widespread rain showers and some thunderstorms and rain moving across all of c New York
and NE PA through 6 PM. Winds are fairly light in the column and
precipitable waters are 1.7 inches and hence we will have threat for heavy
rainfall but at this time there is too much uncertainty for a
Flash Flood Watch and frankly the radar echoes are not that
impressive. Model qpfs are running up to 1 inch or so which
suggests convective potential of 1 inch per hour or so. We will
continue mention in severe weather potential statement and monitor.
Previous dscn below...
at 415 am...local radars trends during the past several hours
showed activity over western New York both weakened and become
scattered. Stronger activity has developed recently over eastern
Ohio and western PA where instability and middle level lapse rates
are more favorable for convection.
500 mb low over northern Michigan and associated weak surface reflection will
slowly track east today. As this occurs middle level short waves
rotating around upper level feature will spread showers and
embedded thunderstorms across New York state primarily west of i81 this
morning with activity spreading into the eastern portion of forecast area and
northeast PA this afternoon. Due to fairly high precipitable waters (1.50-1.75
inches), model soundings indicating tall/skinny cape and a fairly
deep warm cloud layer any convective elements will be capable of
producing heavy rainfall. This is not a widespread heavy rainfall
event but more of a localized heavy rainfall scenario depending on
where the stronger convective cells develop. Since its been dry
recently, rainfall around 3 inches will be needed in a short
period of time (3 hours) before any significant flash flooding
begins to occur. Will continue to advertise likely probability of precipitation for
showers by middle afternoon across all of central New York and northern tier of
PA with chance probability of precipitation in the far southeast. Due to some instability and
forcing will continue with chance of thunder.
Short term /6 PM this evening through Friday night/...
tonight through Thursday...upper level feature and weak surface
reflection will slowly drop southeast during the period and reside
over central New York by Thursday. Period will continue to be wet with
likely probability of precipitation over central New York and high chance for NE PA. Airmass will
remain very juicy with the potential for heavy downpours and
localized flooding especially in central New York.
Thursday night through Friday night...conditions will gradually
improve as upper level low fills and moves east of forecast area. Will
continue with chance probability of precipitation Thursday night through Friday but mainly
dry by Friday night.
Long term /Saturday through Tuesday/...
same pattern that we have seen for much of the Summer continues with a
trough over new eng and ridging to the west. Nearly stationary warm fnt
boundary over western New York will be the focus for conv...and keep chance
or slight chance over the area for much of the period. Ll southeasterly flow will
keep cooler air in the area and afternoon temperatures especially below normal. Upper low
slowly deepens off the new eng CST allowing a slow retrograde of
the upper ridge. This in turn shd allow for gradual drying and imprvg
weather Sunday and Monday.
HPC guidance seemed rsnbl and was flwd through the period.
Aviation /15z Wednesday through Sunday/...
a storm system is slowly approaching the region from the west this
morning and mostly VFR with embedded MVFR ceilings are present. Expect
fog from last night to lift shortly after 12z. Showers will develop
over the region late afternoon and prevail through the reminder of
the taf period with VFR ceilings and MVFR visbys. IFR visbys are
possible this afternoon and tonight but confidence is too low on
where the heaviest rainfall will be... thus decided to keep
mention out at this time. Embedded thunder is also possible this afternoon
but also decided to leave it out also due to low confidence. Ceilings
are expected to fall from VFR to MVFR late tonight close to 12z.
Winds will be light through the period.
Wednesday aftn-sun...MVFR restrictions possible in afternoon shra/tsra...and
light overnight fog/St.