Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Newport/Morehead City NC
421 PM EDT Friday Mar 14 2014
high pressure will continue to slide offshore tonight. A cold
front will approach from the northwest Saturday and move into the
region late Saturday night. The front will stall just to the south
Sunday through Tuesday as a series of low pressure systems move
east along the boundary. High pressure will build in from the
north Tuesday and slide offshore Wednesday. Another cold front
will cross the area Thursday.
Near term /through tonight/...
as of 230 PM Friday...high pressure will continue to push offshore
tonight with SW flow persisting. A weak middle level shortwave will
move across the area bringing increased middle and high
clouds...however the low levels will remain dry and not
expecting any precipitation. The exception could be over the coastal
waters south of Hatteras where deeper moisture and better low
level convergence resides near the Gulf Stream. Clouds and light
SW flow will bring much milder temperatures tonight with lows generally
in the middle 40s to around 50 along the coast.
Short term /Saturday/...
as of 230 PM Friday...the shortwave moves offshore Sat morning with
zonal flow developing aloft. Middle level clouds push east during the
morning but will likely see high cloud continuing much of the day.
High pressure continues offshore with SW to west flow persisting ahead
of a cold front approaching from the northwest. A mild day in store with
low level thicknesses around 1360m supporting high in the lower
70s inland while coastal sections will see highs in the middle to
Long term /Saturday night through Friday/...
as of 4 PM Friday...unsettled weather pattern through much of the
long term period as several short waves in a progressive upper
pattern are expected.
Confidence in timing of the first batch of unsettled weather is
high...and therefore maintained categorical probability of precipitation late in the
weekend into the beginning of the work week. Discrepencies in
model solutions develop Monday night into the end of next week and have
therefore limited probability of precipitation to chance category.
Weak backdoor cool front will work its way through east NC overnight
Sat...stalling over the area on Sunday. Inverted surface trough will
develop along this boundary and promote low pressure development over
the region through the day Sunday. Strengthening SW 850 mb flow will
increase fgen/isentropic lift sun and continue through Sun night. Have
an increase pop trend Sun morning from SW to NE...with column rapidly
becoming saturated per model soundings by afternoon and therefore
inherited categorical probability of precipitation look good. Several waves of low pressure
look to keep the rain threat ongoing through the overnight Sun
night as upper flow remains southwesterly with NE surface winds continuing. It
appears now the heaviest rains will be across the eastern half of
the forecast area...though ultimately the exact placement of the mesoscale
boundaries will dictate the area of heaviest rainfall.
Probability of precipitation in the 60-70 range on Monday as forcing aloft wanes
somewhat... though still appears a raw cloudy day with light rain
or drizzle throughout the day. Maximum temperatures only in the upper 40s
inland to middle 50s southern coast with continued NE winds.
Larger model discrepencies for Monday night into Tuesday so pop forecast is
low confidence at this time. Wide spread in European model (ecmwf) ensemble members even
though operational European model (ecmwf) dries the column considerably by Monday
night. GFS indicates a stronger middle level vorticity propagating through
mean flow aloft Monday night into early Tuesday though this feature
appears to be polluted with convective feedback. Due to the
uncertainties have trimmed back probability of precipitation to the 30-50 percent range.
Thermal profiles still support mainly a cold rain throughout the
period so will keep all liquid ptype for now. Though there may be
a potential for some sleet or even some mixed snow at times
especially Monday evening...though impacts are expected to be
neglibible if this happens due to marginal surface temperatures. A prolonged NE
flow may also result in minor coastal flood issues and high surf
for the northern Outer Banks through late Tuesday.
Unsettled weather may plague the area middle week as return flow
develops. Again there are uncertainties in model solutions due to the
progressive nature of the middle level flow pattern...with the European model (ecmwf)
on the wetter side with higher precipitable waters and GFS on the drier side.
Have indicated low chance probability of precipitation. Temperatures will be rebounding closer to
climatology Wednesday into Thursday with the ensuing return low level flow.
Aviation /20z Friday through Wednesday/...
short term /through Saturday/...
as of 230 PM Friday...VFR conditions will persist through the taf
period. A shortwave trough will pass across the area tonight
bringing increased middle and high clouds but the low levels will
remain dry with ceilings expected to remain above 10k feet. SW winds
will continue to gust around 15-20 knots this afternoon with light
mixing continuing tonight preventing any fog concerns. West/SW winds
expected to gust to around 15-20 knots Sat ahead of a cold front
approaching from the northwest.
Long term /Sat night through Wednesday/...
as of 4 PM Friday...a weak front will move through the terminals Sat
night into Sunday morning...with a series of low pressure systems
moving along the front Sunday night into Tuesday. Prolonged period
of sub-VFR conditions expected to develop sun...with a good chance
of IFR ceilings and occasional rain Sun night through Monday evening. Improving
conditions possible Tuesday with a lesser chance of rain though
sub VFR conditions may persist.
short term /through Saturday/...
as of 230 PM Friday...SW winds increase to 15 to 25 kts this evening
and overnight with the high offshore and front approaching well to
the northwest. Highest winds are expected over the central waters and local
Swan models shows some 6 foot seas developing east of hat late and will
continue Small Craft Advisory for just central waters late tonight into middle morning Sat.
SW/west flow around 10-20 knots continues Sat ahead of approaching
frontal boundary. Seas subside to around 2-4ft during the
Long term /Sat night through Tuesday/...
as of 4 PM Friday...a backdoor cold front is prognosticated to move south
across the waters late Sat night into early sun with NE winds
increasing behind it. However it appears the winds will remain sub
Small Craft Advisory at this time as the front weakens over east NC. A series of low
pressure systems will ride along the stalled front. Initial low
will move through Sun night into Monday with winds turning SW across
the southern half of the waters. Exact track of this low will
dictate whether NE flow continues over the northern waters and
sounds...and also whether Small Craft Advisory criteria is met in the southern
waters with strong SW flow. A stronger low is expected to move
just south of the waters Monday night into Tuesday and this will bring a
good chance of Small Craft Advisory conditions in high winds and waves to all of
the waters with strong north-northeast winds. Some indication that there may
be gale criteria met later Monday afternoon into evening as low pressure
strengthens off the NC coast. Seas build to at least 8-12
feet...highest off the northern obx in response to the long NE fetch
early next week.
as of 1145 am Friday...will continue Special Weather Statement for enhanced fire danger most
areas this afternoon. Relative humidity has dropped to 20-30% area
wide late this morning and expect slightly lower min relative humidity values
than previously forecast. Many areas away from the immediate coast
could see min relative humidity in the 15-20% range early to middle afternoon. High
pressure slides offshore this afternoon with southerly return flow
developing allowing dewpoints to begin to increase late this
afternoon. However...SW winds will also gradient increase with gusts
18 to 23 miles per hour middle to late afternoon.
Marine...Small Craft Advisory from 2 am to 10 am EDT Saturday for