Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
1049 am EDT Sat Aug 1 2015
a weakening cold front will move across the region today, followed
by high pressure influencing the Middle Atlantic States on Sunday. The
next cold front is expected to cross our region late Monday into
early Tuesday, eventually stalling offshore to our southeast into
Wednesday and Thursday.
Near term /until 6 PM this evening/...
no significant changes made to the forecast so far. Only some
minor hourly grid adjustments, mainly temperature/dewpoints and sky
cover. Otherwise, forecast looks good; mostly dry with a isolated
showers/thunderstorms, mainly north.
A mostly dry day is expected across the region even as a weak cold
front/wind shift slides through this afternoon and evening.
Dewpoints behind and ahead of the front are relatively uniform so
not expecting a great deal of moisture convergence or stronger lift
with this feature. The best dynamics stay to our north this
afternoon as we maintain the slight chance probability of precipitation across our northern
zones this afternoon. MLCAPES get close to 1000j/kg but only for a
brief time period as we could have more interaction with a thermal
trough in northern New Jersey than anywhere else today.
Stronger heating combined with the lower humidity values should make
for a mostly sunny day...convective temperatures look just out of
reach. Better vertical mixing will allow for gusts upwards of 25 miles per hour
this afternoon with the frontal/wind shift passage. Overall a warm
but pleasant day expected.
Short term /6 PM this evening through 6 am Sunday/...
any diurnally driven showers dissipate with the loss of the daytime
heating and we lose the gusty winds. Any cumulus that forms will also
decrease in coverage giving way to mostly clear skies. It may take a
while to lose the sustained winds before decoupling but expecting
our sheltered locations to see temperatures drop back into the low-
60s with even cooler dewpoints.
Long term /Sunday through Friday/...
a quiet start to the long term is anticipated as an area of high
pressure to our southwest, centered over the central Appalachians,
extends east and influences the Middle Atlantic States. Ample sunshine
is expected across the region Sunday, with near to slightly above
average temperatures, as highs reach mostly into the middle/upper 80s
with a few areas nearing 90 degrees. Dewpoints will remain
tolerable, ranging mainly from the upper 50s to low 60s.
Into the new work week, a more active, unsettled pattern is expected
as a cold front approaches the region from the northwest during
Monday. The cold front is prognosticated to gradually pass through the
region from late Monday into early Tuesday, but timing and coverage
of any shower/tstorm activity associated with this boundary and some
shortwave energy aloft remains uncertain, and for now, we have kept
some slight chance probability of precipitation focused across the northwest half of the
forecast area where there should be somewhat better forcing and
lift. Into Tuesday, the cold front is prognosticated to be passing south
and east of our area, eventually stalling offshore. While overall
coverage of any pop-up showers/thunderstorms looks to be low, some slight
chance probability of precipitation have been kept as some model guidance shows another
possible shortwave aloft perhaps moving over the region later in the
This overall unsettled pattern looks to continue through Wednesday,
Thursday, and perhaps into Friday, with the stalled frontal boundary
remaining nearby just to our south. Timing and coverage of
shower/tstorm activity remains uncertain at this extended range, and
while a complete washout is not expected in the middle to late week
period, both the GFS and European model (ecmwf) show the potential for a wave of low
pressure to develop and move along the stalled boundary in the
Thursday timeframe. We therefore have focused some higher chance
probability of precipitation for the area on Thursday. Otherwise with above average
uncertainty, we mostly used a blend of wpc guidance with continuity
through the latter part of the long term period for temperatures,
pops, and winds.
Aviation /14z Saturday through Wednesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
Today...VFR. Light southerly winds will veer towards the west-
southwest and increase later this morning. Some gusts upwards of 20
knots look to occur at most of the terminals. Isolated showers with
embedded thunder should stay north of Abe this afternoon.
Tonight...VFR. Mostly clear skies with light westerly winds.
Sunday...VFR conditions are expected.
Monday through Wednesday...mainly VFR conditions through this
period; although, some isolated to perhaps scattered showers/thunderstorms
sub-Small Craft Advisory conditions expected today and tonight. Weak cold front moves
through our waters this afternoon. Southwesterly flow ahead of the
front veers towards the west-northwest late tonight with some
gustiness...we should stay below 20 knots. Seas will see an increase
towards 4 feet across the northern waters this evening and then
subside as the winds turn offshore.
Sunday...sub-advisory conditions are expected.
Monday and Tuesday...mainly sub-advisory conditions; however, some
wind gusts could be around 25 knots plus with seas increasing for
the coastal waters late Monday into early Tuesday associated with a
cold front passage.