Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
106 am EDT Sat Aug 23 2014
upper ridging will slowly build over the region by late today
and Sunday...bringing an end to the recent siege of shower and
thunderstorm activity. The upper ridge will dominate the weather
pattern over the northeast United States and southeastern Canada
from the early to middle of next week...with the next chance of
rainfall possible late Wednesday or Thursday from an approaching
midwestern frontal system.
Near term /until 8 am this morning/...
weak surface low near kidi...and a backdoor front pressing slowly
westward from the susq valley early this morning will lead to a
mainly cloudy and mild night with isolated...slow moving moderate
to heavy rain showers.
Digital precipitation rates have dropped off significantly over the past
hour with just a few small areas exceeding one inch per hour.
Rates just prior to 0330z were over 4 inches per hour in some
locations. Warm cloud depth is several kft...and no lightning has
occurred in these tropical like rain showers across the County Warning Area over
the past several hours. 2 areal flood advisories issued across the
middle susq valley for minor flooding of poor drainage areas and
small streams will expire shortly. Although additional...briefly
very heavy showers are possible near the slow moving backdoor
front in vicinity of kipt and kseg... it appears that the focus for
heavy rain will be across our SW zones in vicinity of of the aforementioned
quasi-stationary surface low...with better low level moisture convergence and
still just over 500 j/kg of surface based cape. Across most of the
central and northwest zones...conditions should stay dry for most places
Towards dawn...the moist easterly flow ascending the higher
terrain of central PA will likely result in developing low
stratus/ridge-shrouding fog and patchy drizzle across the central
mountains temperatures will remain mild under cloud cover...with lows
generally in the lower to middle 60s.
Short term /8 am this morning through 6 PM Sunday/...
expect one more moist day is in store for Saturday...with onshore
flow and slowly departing upper trough along the northern middle
Atlantic Seaboard combining to produce additional shower activity.
Widespread low clouds and patchy morning drizzle and fog may
persist well into Sat afternoon...keeping temperatures well below normal
on Saturday. Portions of the central/northern mountains may struggle to
climb out of the upper 60s. Far northwest sections...away from
the maritime flow and in downslope flow...may warm into the 70s.
The resulting instability could potentially result in a PM thunderstorms and rain
across Warren Colorado.
Long term /Sunday night through Friday/...
much of the extended will feature a ridge dominating the pattern
over the eastern and northeastern US.
The lingering effects of the trough over the northestern US sliding east
may keep a few showers in the picture Saturday night...otherwise
fair weather will develop along with warming temperatures as the
ridge establishes itself and maintains its hold until at least
Thursday when the next frontal system is advertised to
approach...albeit in different fashions by the various medium range
The operational GFS and European model (ecmwf) keep US dry through at least later
Wednesday while the gefs is more pessimistic bringing measurable
rains east quicker under a flatter upper flow. The gefs upper
pattern more closely resembles the operational European model (ecmwf) showing a
weaker trough hanging back in the middle west as heights in the east
slowly fall with the East Coast ridge flattening out in time.
The differences are at the end of the forecast period throwing
doubt on the forecast so I opted for a rather Bland chance of
showers starting Wednesday night lasting into Thursday night.
Overall the last full week of August will be a summery one for
the first days of school in many communities. Temperatures will be near
to a bit above normal Monday...then will remain above normal at
least through the end of the week when the airmass situation
becomes a little less certain.
Aviation /06z Saturday through Wednesday/...
still a few storms near jst.
Another batch from near ipt...southward across seg...to near MDT.
03z tafs will be adjusted for this.
Earlier discussion below.
As was the case yesterday...there is 2 areas of storms. One across
the south...and one across the north. The strongest storms are
across the north...where there has been more clearing today.
Can see the strongest storms out the window here.
Anyway...21z taf package updated. Did one at a time...given type
of conditions present...instead of sending all as a groug at
Showers are most numerous across the central... west central
mountains and south central mountains at midday and early this
afternoon...along with isolated embedded thunder. Brief thunderstorm visibility
and ceiling impacts are possible through late afternoon...and any
lingering storms should decrease in coverage and intensity into
A large area of high pressure will build southwestward from eastern Canada into the
northeast and down the east side of the applchns tonight through the
weekend. Easterly flow should bring low clouds/ceilings into the forecast
with some light rain/dz early Saturday with a few showers possible
later in the day. Look for improving conds sun through Tuesday.
sun...low ceilings possible early then becoming VFR.
Mon-Wed...VFR no sig weather.
long term...la corte