Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
1245 PM EST Friday Nov 28 2014
high pressure will build east across the Ohio Valley today then off
the middle Atlantic coast on Saturday. Low pressure tracking out of the
northern plains will pass north of the Great Lakes on Saturday night
and pull a warm front north across the area. The associated cold
front will push south across the area on Sunday night with high
pressure building over the western Great Lakes on Monday.
Near term /until 6 PM this evening/...
flurries continue across northeast Ohio and northwest Pennsylvania
but area of precipitation is beginning to lift north as flow
begins to shift on the upper side of the ridge of high pressure.
Some clearing was developing across the lake at this time but will
quickly be overshadowed by middle and high clouds from the west with
the next upper level positive vorticity maximum. Backed off on
temperatures a tad as expected highs will likely not be reached
Short term /6 PM this evening through Sunday night/...
upper level pattern becomes more zonal by tonight with increasing
warm advection aloft. The GFS is an outlier in showing over 0.20 quantitative precipitation forecast
across our northern County Warning Area overnight while the majority of the other
models just clip our NE County Warning Area with light precipitation. Although the
GFS has been showing a little better coverage of precipitation for
the past several runs...the 00z run had at least double the quantitative precipitation forecast from
what most of the previous runs were showing. It is not entirely
clear what is driving the higher precipitation shown by the GFS but
the 500mb vorticity pattern does not look great and could have some
errors. Will lean towards the better consensus offered by the other
models which show increasing low level dry air interfering the the
snow and only carry 50-60 probability of precipitation in NE Ohio/northwest PA with less than an
inch of snow.
A Big Warm up is expected over the region as low pressure passes
north of the Great Lakes region. Highs on Saturday will only make it
to the lower 40s...but we will surge into the 50s on Sunday with
strong southerly flow. Although the moisture will be
shallow...models do suggest periods of light rain or drizzle in the
warm sector from late Saturday afternoon through Sunday.
Precipitation during this time will be light...then increasing
Sunday night as the cold front arrives. Precipitation type will
remain all rain through Sunday night.
Long term /Monday through Thursday/...
the cold front should be southeast of the forecast area by the start
of the period. The big questions today are how fast the precipitation will
cutoff behind the front and if it will cool enough to change the
rain to snow before the precipitation ends. Similar to the previous
forecast will keep a chance of mixed precipitation going Monday morning.
The 00z GFS has the area dry on Monday but the other guidance
including the new European model (ecmwf) keeps the precipitation around a little longer
which seems reasonable. High pressure will move across the region
on Tuesday keeping the area dry. Warm air advection will get going
Tuesday night into Wednesday. The models are indicating that there
could be enough warming and moistening to get another round of light
precipitation. Will go with chance probability of precipitation both periods. Precipitation type still
somewhat up in the area. It should be cold enough for mainly snow
on Tuesday night but a switch to rain is likely on Wednesday. A
cold front will sneak across the region late in the day and some
lake effect activity could occur on Wednesday night for a few
hours. High pressure and dry weather will return for Thursday.
High temperatures during the period will be mainly in the upper 30s and a
good 5 to 7 degrees below normal.
Aviation /18z Friday through Wednesday/...
still a few light lake effect snow showers/flurries northeast of a kcle
to kyng line. These will gradually decrease through the afternoon
as high pressure shifts winds around to the southwest and eventually
to the south. There will be a lull in the activity until the warm
advection increases over the area late this evening into the
overnight hours. The chances of some light snow will increase
overnight but it looks light. There is a small window of time
closer to sunrise where some very light freezing drizzle will be
possible. Have placed a prob30 in the taf sites that have the best
chance of this occurring. The freezing drizzle looks to be very
light and a short duration but could cause significant issues.
There may be a few areas of MVFR cloud cover under the heaviest
returns on radar tonight into Saturday morning.
Southerly winds will increase on Saturday and may gust up to 25
knots. Some light rain showers may develop by 18z Saturday in the
Outlook...non-VFR returning Sunday into Monday in light showers
with the next front.
a ridge will slide east across Lake Erie today. The flow on the
western basin will become SW this morning and with speeds already
coming down have gone ahead and removed the small craft from that
area. Will continue with a small craft over the remainder of the
nearshore through 10 am. Depending on how fast winds die down...the
day crew may need to extend it for a couple of hours. South to
southwest flow is then expected on the lake till a cold front
crosses the lake Sunday night. The lake could again need a small
craft for most of Monday. High pressure will slide east over the
lake by the end of the period causing winds to lessen and take on a