Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
352 PM EDT Thursday Jul 31 2014
weak high pressure will remain across the region tonight and into
early Friday. Several weak disturbances and a coastal front will
affect the area this weekend. High pressure will build across the
area early next week. Another disturbance will move toward the
area toward the middle of next week.
Near term /through tonight/...
fair weather cumulus clouds have developed across the region due to
daytime heating this afternoon. The passing shortwave has moved well
off to the north. This evening should be a dry one, except for the
slight possibility of a passing shower or thunderstorm northwest.
Probability of precipitation were lowered based on radar/satellite trends. Another cool and
comfortable night is in store for most of US, with the exception
being Delaware and south Jersey where humidity will be nudging ever
so slightly higher. Some low clouds and brief localized fog is
possible towards sunrise as well. Stayed close to the mav/met on
temperatures tonight and adjusted the evening temperatures slightly
based on the latest metar observation and incorporated the latest lamp/lav
guidance. Clouds will be on the increase ahead of the next system by
Short term /Friday/...
another shortwave to our west will cause a southeasterly flow to
develop over the region and an offshore front to back and move
closer to the coast. As a result, moisture will be on the rise on
Friday, both at the surface and at mid-levels. It will feel muggy
again just in time for August. Although the onshore flow will lessen
any instability that develops, showers and isolated thunderstorms
will still be possible in the afternoon Friday with the greatest
threat in the western parts of the region where the southeast flow
will have a lesser impact on instability. Cape values are expected
to be near 1000 j/kg in the western part of the region, and around
500-800 j/kg elsewhere. This will limit the threat for strong
thunderstorms but will still enough to have thunder in the grids.
Went a touch cooler than the mav/met for temperatures based on the
likelihood of clouds and spotty showers. Not sold on the wetness of
the NAM/sref in terms of qpf, so went rather light with this
element. Due to the spotty nature of any showers in the afternoon
went fairly low with chance probability of precipitation and slower timing on any rain when
compared to the NAM/GFS more in line with the rgem/ECMWF.
Long term /Friday night through Thursday/...
an unsettled period expected this weekend into early
Monday...before an improving picture next week.
A front/inverted trough will linger along the East Coast this
weekend while upper heights begin to build. The upper high across
the ocean will begin to build back across the area late this
weekend into next week. This will bring an onshore flow with
abundant moisture this weekend. Scattered showers and thunderstorms will be in
the forecast for Friday night and through the weekend. Temperatures will
hold to mostly normal or a bit below normal with all the extra
cloudiness. It will be a rather humid period however.
By Monday...the building high will cause the onshore flow to
weaken and the mean flow aloft will switch to move wrly/swly. This
will allow drier air to arrive...but also warmer temperatures.
Highs Tuesday-Thursday will mostly be in the middle/upper 80s across the southern
areas and low/middle 80s north. These temperatures are at or a bit
above normal. Scattered showers early Monday...then a mostly dry forecast
for next week.
Aviation /18z Thursday through Tuesday/...
general southwest winds this afternoon at all taf sites possibly
becoming more southerly tonight before becoming variable. Any gusty winds
should subside with loss of daytime mixing. Took out any groupings
with vcsh in it as the coverage is very localized away from the taf
sites at this time. Low clouds/patchy fog are possible tonight and showing
up on some BUFKIT soundings. Kept tafs more optimistic at this time as GFS/NAM
guidance is mixed on this with the NAM hitting harder. Climatology
suggests a 40% of MVFR conditions as well, giving some confidence to
lowering ceilings/visibilities but keeping VFR. Brought in a gradual
overcast tomorrow from south to north at about 10,000 feet lowering
it at phl by 15z. Showers we're not added to the tafs for tomorrow
given the highest chance is after 18z.
Friday night through Sun night...lower ceilings expected at times with on
onshore flow. Scattered showers/thunderstorms at times with lower visibilities.
Monday through Tuesday...mostly VFR with scattered showers.
seas and winds are expected to remain below Small Craft Advisory criteria at this time. Seas are
likely to be around three feet and winds less than 10 knots.
Outlook... Friday night through Tuesday ... Small Craft Advisory conditions expected
through the period. Scattered thunderstorms will create locally higher winds and