Area Forecast Discussion
Issued by NWS Newport/Morehead, NC

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FXUS62 KMHX 272215

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
615 PM EDT Sat May 27 2017

A frontal system will drift south into the area tonight and
become stationary through Sunday, then lift northeast Sunday
night. A cold front will drift in Monday night and become
stationary along the coast through the end of the next week.


.NEAR TERM /Tonight/...
As of 615 PM Sat...Convection has initiated in ctrl VA as
expected early this evening. Poor man`s ensemble of the meso
model suite indicates this activity advecting ESE into nrn NC
through this evening and potentially impacting our nrn counties
generally north of hwy 64 after 02Z (10pm). Attm WRF_ARW is
performing fairly well with this convection and have blended
more heavily with this model through the overnight. Have inc
pops across the north to 40-60 percent with just a 20 pop far
south. Most likely this convection will move into the FA as an
outflow/cold pool dominated MCS as sfc based instability wanes
late tonight, though ML CAPES still sufficient for some strong
to potentially damaging wind gusts.

Previous discussion...As of 330 PM Saturday...A few cumulus
have develop over mainly inland areas late this afternoon as
temperatures have risen to around 90 degrees well inland with
low/mid 80s coast. Latest 3km HRRR, 4 km NAM and NSSL WRF are
fairly consistent in showing line of convection associated with
approaching frontal boundary and mid-level shortwave energy to
arrive at around 02z- 03z over the Albemarle Sound region. The
highest PoPs will be over the northeastern counties/Sounds
region with only a slight chance over the far south as any
convection should wane during the late night hours. The
northwestern counties remain in a Slight Threat of severe
tonight with decent shear but diminishing instability after
midnight. Lows tonight should be in the upper 60s to lower 70s.


As of 335 PM Saturday...Frontal boundary will drift south
through the CWA before dissipating Sunday afternoon as winds
quickly come back around to S/SW in the afternoon. Any leftover
boundaries along with heating as temperatures climb back toward
90 degrees will ignite a few scattered showers and thunderstorms
during the afternoon, mainly inland. With respectable
instability and weak low-level shear, some strong storms will be
possible, but only expect scattered coverage and will keep PoPs
at 30 percent inland and 20 percent coast. Highs Sunday will be
90-93 inland and 83-87 coast.


As of 425 PM Saturday...An unsettled pattern will be the rule
through the extended period as shortwaves/disturbances move
through the region aloft, with weak frontal passages moving into
the area and stalling Monday night and Wednesday night. These
features will lead to continued low confidence through the period
due to timing of shortwaves/frontal boundaries across area.

Sunday night-Monday night...A weak shortwave will move through
the region Sunday evening ahead of a stronger shortwave that
will move through VA late Sunday night into Monday morning.
Trended PoPs from high chance Sunday evening to slight chance
after midnight. Models generally agree on more widespread
convective threat with a stronger shortwave trough and surface
cold front moving toward area during peak afternoon heating
Monday. GFS/NAM forecast soundings indicate MUCAPE values of
2500-3500 with deep layer shear (0-6km) increasing to near 50
KT, thus increasing concern for strong to severe storms. SPC
continues Day 3 Outlook of Slight Risk of severe for entire
area. Brought PoPs down Monday morning due to lack of moisture
and brief subsidence behind departing shortwave, then maintained
PoPs in the 40 percent range for the afternoon. Guidance
indicates low level thicknesses building to near 1430 meters,
supportive of max temps 90-94 inland, with mid to upper 80s
along the coast. Lows Monday night remaining muggy 70-74.

Tuesday-Tuesday night...The frontal boundary is expected to
stall across the area Tuesday morning, and wash out across area
with additional short wave energy resulting in another period
of mainly diurnally driven showers and thunderstorms. Tuesday
afternoon convection could be similar to or exceed Monday`s
activity, mainly because of better moisture focused along the
stalled front and channeled shortwave/vorticity over the region
coincident with peak afternoon heating. More cloud cover and
lower thicknesses will keep max temps mainly in the 80s. Lows
Tuesday night 66-70 inland to lower 70s coast.

Wednesday-Saturday...Low confidence for this forecast period
due to poor model continuity. 12Z guidance continues the wet
trend for Wednesday and Wednesday night, though the ECMWF
suggest the stalled boundary may be farther offshore than the
GFS/GEM. Drying trend for Thursday looks good with front off
coast. Higher chance PoPs for Friday with front lifting back
north, helping to focus moisture over the area through Saturday
morning. Max temps still in the mid to upper 80s for Wednesday
and Thursday, then low 80s for Friday and Saturday due to cloud
cover and showers/thunderstorms. Lows from mid 60s to lower


Short Term /through 18Z Sunday/
As of 615 PM Saturday...VFR through the TAF PD. Thunderstorms
may impact the area after 10 pm, with KPGV seeing the best
chance of thunder tonight. Storms may tempo limit vsbys to
IFR/MFVR in heavy rain along with tempo gusty and erratic wind
gusts. May need to add a VCTS or tempo TS with later updates
after 02Z. Any storms move off and weaken late in the overnight
with benign conditions through much of Sunday.

Long Term /Sunday night through Thursday/
As of 410 PM Saturday...Sub-VFR conditions likely Sunday night
as a weak front and upper level disturbance move through the
area. Better chance for periods of sub-VFR with convective
activity each afternoon and evening from Monday through
Thursday. Less coverage for Wednesday and Thursday but sub-VFR
could linger with front stalled over area.


Short Term /Tonight and Sunday/
As of 345 PM Saturday...Winds continue to be SSW/SW at 10-15
knots with a few higher gusts at late afternoon with seas at
1-3 feet. Frontal boundary will enter the far northern waters
late tonight and will work its way south before dissipating
Sunday afternoon as the winds quickly become S/SW again. Expect
seas to perhaps rise to as high as 4 feet over the coastal
waters tonight but should drop back to 2-3 feet on Sunday per
latest SWAN/NWPS model.

Long Term /Sunday night through Thursday/
As of 430 PM Saturday...Zonal flow with weak disturbances aloft
will lead to several weak frontal intrusions into the area
Monday night and again Wednesday night. Southern half of waters
will mainly see SW winds 5-15 knots during period but northern
waters will see some periods of shifting winds but with speeds
less than 15 knots. Southern waters will see some periods of
seas building to 4 feet for outer portions with stronger SW
winds around 15 knots, otherwise seas mainly 2-3 feet during the
extended period. NWPS and Wavewatch in good agreement through
the medium range, with Wavewatch appearing reasonable for the
extended seas forecast.




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