Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Newport/Morehead City NC
714 PM EDT Thursday Apr 17 2014

Synopsis...
high pressure extending down the eastern Seaboard will weaken and
move northeast Friday. Low pressure will develop in the Gulf of
Mexico Friday. The low will move off the southeast coast Saturday
night. It will continue to slowly move northeast early next week.
A cold front will move through Tuesday night. High pressure will
build in Wednesday and Thursday.

&&

Near term /until 6 am Friday morning/...
as of 700 PM Thursday...lowered overnight mins slightly to near 40 well
inland and middle to upper 40s coast...otherwise init for current conds. M
models in very good agreement in the short term. Narrow ridge of
high pressure will continue to extend down the eastern Seaboard.
Low pressure developing in the Gulf of Mexico late tonight will
begin to spread low level moisture into the area. Low temperatures will
range from lower 40s coastal plain to lower 50s Outer Banks.

&&

Short term /6 am Friday morning through 6 PM Friday/...
as of 330 PM Thursday...moisture continues to increase. Models show
Theta-E ridge building in from the east southeast. Isentropic lift
will increase as the low moves east northeast and expect light
rain to spread in during the afternoon over the southern counties
and adjacent coastal waters. Highs range from the upper 50s
northern Outer Banks to middle 60s southwest.

&&

Long term /Friday night through Thursday/...
as of 330 PM Thursday...deep trough moving through the Gulf Coast region
will cut off then move through the deep south and off the southeast coast.
This will set up a mainly cloudy and wet pattern over the forecast
area for much of the upcoming weekend.

Rain will begin to spread into eastern NC as an area of isentropic
and deep moisture approaches from the south Friday night well ahead of
the main Upper Cutoff low. Have ramped up probability of precipitation to likely over all
but far northern areas (which is on the northern fringes of the main
precipitation area) later Friday night through Saturday morning. There are still
model differences in the northern extent of precipitation shield
particularly with the drier NAM solution so probability of precipitation may need to be
adjusted as details can be further defined with later model runs.
Temperatures will cool into the upper 40s inland to low to middle 50s coast
Friday evening before leveling or rising toward Saturday morning.
Temperatures may struggle to reach into the low to middle 60s Saturday
depending on how much precipitation overspreads the area.

The upper low gradually moves off the southeast coast and into the western
Atlantic during the latter half of the weekend. This slower movement
lends itself to a cloudy and potential wet Sunday particularly for
coastal areas. The forecast will show a gradual decrease in probability of precipitation
from northwest to southeast from late Saturday through Sunday night again in
deference to the drier NAM solution but gut feeling is that cloudier
cooler and wetter Sunday will occur given the overall more
pessimistic model trends. Again forecast details can be adjusted as
later model runs come into more alignment.

There may be a sharp gradient of rainfall from north to south but
if the wetter models solutions hold, rainfall amounts could exceed an
inch or more over southern areas this weekend.

There is decent model agreement for clearing skies and temperatures
at more seasonable levels early next week. Milder low level SW flow
will increase ahead of an upper trough approaching from the northwest Tuesday
into Tuesday night. Will cap probability of precipitation at slight chance for this forecast
period for now given the lack of moist inflow given middle level west-northwest
flow. Midweek weather looks dry and seasonable as upper ridge builds
toward the East Coast.

&&

Aviation /23z Thursday through Tuesday/...
short term /tonight & Friday/
as of 7 PM Thursday...VFR through the short term. Gusty northeast
winds will diminish quickly this evening then less than 10 knots
overnight. Mostly clear this evening but increasing low level
moisture forecast after midnight and continuing during the day
Friday. Ceilings developing in the predawn hours Friday around 5
kft. Some light rain possible in the afternoon Friday at southern
terminals oaj and ewn...with isolated and pgv remaining dry. Northeast
winds during the day remaining around 10 knots.

Long term /Friday night through Tuesday/...
as of 330 PM Thursday...as rain spreads NE into the area Friday night
into Sat expect reduced flight categories espcly southern tier where
best covering of rain expected. As low pressure drifts further offshore to
the southeast Sunday, very gradual improvement expected with mainly VFR
returning by late Sunday into Monday.

&&

Marine...
short term /tonight & Friday/
as of 700 PM Thursday...main change to extend Small Craft Advisory for Albemarle and
Alligator river through this evening. Models remain in very good
agreement in the short term. Northeast flow continues in between
high pressure extending down the eastern Seaboard and a stationary
front over the offshore waters. Small craft advisories will
continue through early next week for the coastal waters.

Long term /Friday night through Tuesday/...
as of 330 PM Thursday...strong high pressure extending into the Carolinas
Friday night will maintain north-northeast winds of 15 to 25 kts near the CST. As
low pressure slides east-northeast to the S Sat into sun expect the gusty north-northeast
winds to continue poss gusting 25 to 30 kts outer waters. The NE winds
will slowly diminish Monday as the low moves further offshore and
high pressure weakens as it builds toward CST. The persistent NE flow
will keep seas elevated through the period with Small Craft Advisory over the coastal
waters continue into Monday night. Seas will peak at 8 to 12 feet over
the outer waters late Sat through Sunday. Then slowly subside to 4 to
6 feet Monday night.

&&

Mhx watches/warnings/advisories...
NC...none.
Marine...Small Craft Advisory until 8 PM EDT Friday for amz135.
Small Craft Advisory until midnight EDT tonight for amz130-131.
Small Craft Advisory until 6 am EDT Tuesday for amz150-152-154.
Small Craft Advisory until 1 am EDT Tuesday for amz156-158.

&&

$$
Synopsis...hsa
near term...jac/hsa
short term...hsa
long term...btc
aviation...jac/btc/hsa
marine...jac/btc/hsa