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Office: ILM

FXUS62 KILM 222234

Area Forecast Discussion
National Weather Service Wilmington NC
635 PM EDT Tue May 22 2018

A tropical airmass will remain across the Carolinas for the next
week. A cold front approaching from the north will create better
chances of showers or thunderstorms Wednesday and Thursday. The
front will dissipate Friday, with fewer showers expected into
Saturday. Low pressure developing this weekend across the Gulf
of Mexico will throw more moisture our way for Sunday and
Monday, with substantial rain chances returning to the area.


As of 300 PM Tuesday...The convection that developed along the sea-
breeze just before noon is now decreasing in coverage. Inland
isolated convection appears to continue as the HRRR 16 UTC is not
showing an increase activity this evening. So will continue with
isolated showers and thunderstorm through the evening.

At the surface the area will continue to be on the eastern edge of
the Bermuda high and the deeper moisture is seen returning with
precipitable water near 2 inches. Both the NAM and GFS are showing
diurnal convection with the GFS being a bit more zealous with
convection in the northwest quarter of the area. The NAM is showing
less precipitation mainly west of the sea-breeze and focused over
northeast South Carolina. The 12 UTC ECMWF is closer to the NAM12

Lows tonight will range from the upper 60s inland to the lower 70s
at the coast. Highs on Wednesday will be in the middle 80s inland
and the lower 80s at the coast.


As of 300 PM Tuesday...The chance for showers and thunderstorms will
increase Wednesday night into Thursday as a cold front drifts south
across the forecast area. The precipitable water will pool ahead and
along the boundary along with marginal to moderate surface based
instability. While the amount of cloud cover will ultimately impact
the amount of instability any increase in cloud cover would also
imply slightly cooler temperatures than what is currently forecast.
For now favor a blend of MAV/MET temperatures, and POPs decreasing
Thursday evening with the front drifting farther south and


As of 300 PM Tuesday...A baggy upper level trough across the
lower Mississippi Valley and Gulf of Mexico will become better
defined Saturday and Sunday. Upper ridges building across the
Pacific coast of Mexico and out over the western Atlantic
between the Bahamas and Bermuda will help to spin this feature
up. A surge of Caribbean moisture very similar to what we saw
last weekend will be drawn northward in the deep southerly flow
between this upper trough and the offshore ridge, and this could
lead to another good rainfall event Sunday into Monday. The
latest WPC QPF outlook for just Sunday and Monday is around 1.5
inches across our area, with forecast 7-day totals of 2-3 inches.

Latest models show there will probably be some sort of low
pressure development across the Gulf of Mexico late this week,
but FSU cyclone phase diagrams show only the Canadian developing
a significant warm core aloft. The 12z ECMWF (not currently part
of the FSU website) shows the cyclone keeping a pronounced
gradient in 1000-500 mb thickness above the surface low,
implying subtropical characteristics at best. The GFS is the
farthest east with its low pressure development across Florida
on Sunday, while other guidance is westward. While not ruling
out anything just yet, it's expected the low will remain too far
west for any direct impacts on the Carolinas, but enhanced
southerly flow should help enhance our rainfall potential Sunday
and Monday when my highest rainfall chances (50-70 percent) are
currently forecast.

The warmest days should be Friday and Saturday when there will
be more sunshine and lower shower chances. Highs should reach
the mid to upper 80s both days inland, several degrees cooler
near the coast. Temperatures should top out in the lower 80s
Sunday, and lower to mid 80s Monday and Tuesday. Lows in the
upper 60s to lower 70s through the period are evidence of the
tropical airmass we'll have in place.


As of 00Z...VFR through the evening hours with a moderate south
southwest flow. Overnight, could see some IFR conditions, mainly
with respect to ceilings. Visibilities will be MVFR as some mid
cloud ceilings above the stratus will hinder fog formation.
Wednesday, time height indicates fairly good moisture through
500 mbs. The LFC should be fairly low and convection should kick off
around noon, with more coverage than today.

Extended Outlook...The potential for MVFR/tempo IFR will increase
late Wed/Thur as a cold front drops across the area and again during
the weekend as tropical moisture returns.


As of 300 PM Tuesday...The marine waters will continue to be
under the influence of the high pressure we have seen the last
few days. Winds will be southwest overnight and will shift to
the south on Wednesday as the sea-breeze develops. Winds will be
around 10 knots increasing to 10 to 15 knots during Wednesday.
Seas will range between 2 and 3 feet through the period.

As of 300 PM Tuesday...Bermuda high pressure will maintain
southwesterly flow across the waters Wednesday evening. However,
the flow will veer to a westerly direction as a weak front
drifts south across the area. The front is expected to become
increasingly diffuse as it passes south of the waters allowing
weak onshore flow to prevail by Thursday afternoon. Seas will
be 3 ft or less through the period. Scattered showers and
thunderstorms are also possible with the front in the vicinity.

As of 300 PM Tuesday...Bermuda high pressure will remain well
off the Southeast coast this weekend. By itself it would provide
a gentle southerly wind and typical summertime weather. However
models over the past few days have been showing the potential
for a tropical or subtropical cyclone to develop across the
Gulf of Mexico Friday or Saturday. The GFS is the farthest east
of any model with its latest run showing a low reaching Florida
on Sunday, while the ECMWF and Canadian are farther west. While
it's too early to completely rule out impacts, our latest
forecast has south winds increasing to around 15 kt Sunday, with
a lengthening fetch of stronger winds extending down into the
Bahamas. This could build seas up toward 6 feet, assuming our
wind forecast is correct.






Office: MHX FXUS62 KMHX 221824 AFDMHX Area Forecast Discussion National Weather Service Newport/Morehead City NC 224 PM EDT Tue May 22 2018 .SYNOPSIS... High pressure will continue offshore through Wednesday. A cold front will move through the area late Wednesday night followed by high pressure building in from the north Thursday. The high will move offshore Friday with a Bermuda high pattern returning for the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 220 PM Tuesday...Scattered convection over the nrn tier expected to lift NE and grad diminish thru early evening. Much of the night expected to be dry with no forcing over the region...did keep slight pops far N late as could see some remnant shra from activity well to the NW. Will be another muggy night with lows upr 60s to lower 70s. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 220 PM Tuesday...A cold front will approach from the N Wed then push SE thru the region Wed night. This front coupled with decent instab and deep moisture will lead to active weather Wed thru Wed evening. Should have enuf heating Wed for good instab to develop and although shear is not very strong NW flow aloft could lead to a strong to poss severe storm mainly acrs nrn tier where marginal risk is fcst by SPC. Have chc pops thru Wed morn then increase to likely later Wed nrn tier. Convection may weaken a bit with loss of heating Wed evening but expect good cvrg to grad shift S along/ahead of front and have likely pops thru evening central and S. Precip shld taper off from N to S late Wed night as drier air spreads in behind the front. Highs Wed mostly mid/upr 80s inland to lower 80s central and srn cst. Lows Wed night 65 to 70 N to lower 70s central and srn cst. && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 340 AM Tuesday...Little change in the overall forecast for the extended period. Pattern flip to a somewhat drier scenario Thursday and Friday. Moisture increases again Saturday with another round of wet weather possible for early next week. Thursday through Saturday...Somewhat drier and slightly cooler weather will prevail Thursday and Friday. With the front sagging over the far southern CWA Thursday morning, will keep a decent chance of showers and thunderstorms for this area early in the day. By afternoon, drier air will be the rule as dewpoints drop into the low/mid 60s, which will be followed by low temperatures into the low/mid 60s inland and around 70 Outer Banks for Friday morning. Good model consensus for a no PoP forecast for Friday as high pressure shunts all of the precipitation to the south of our CWA. Winds veer to S/SW by Saturday as high pressure strengthens offshore and moisture starts to return to the south due to an upper low over the northern Gulf of Mexico. Temperatures warm back to the mid 80s Saturday with a better chance of rain. Sunday and Monday...Deep moisture between low pressure along the central to western Gulf coast and strong high pressure anchored offshore will lead to increasing deep moisture for Sunday into early next week. Will continue forecast of higher PoPs and increasing SE/S winds Sunday and Monday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Short Term /Through 18z Wed/... As of 1230 PM...Mainly VFR conditions expected thru period however will have brief threat for reduced vsbys and cigs in convection mainly nrn tier this aftn and all areas Wed morn thru early aftn. With low lvls remaining nearly saturated cant rule out some lower stratus trying to form late tonight however fcst soundings look marginal and guidance not showing much so will keep out. SW breeze shld limit threat for late night fog. Long Term /Wednesday afternoon through Saturday/... As of 350 AM Tuesday...Widespread showers and a few thunderstorms will lead to frequent periods of sub-VFR conditions Wednesday aftn into Wednesday night. A somewhat drier airmass arrives Thursday and Friday behind a back door coldfront with VFR conditions likely. Increased moisture and a return to shower and thunderstorm activity will lead to a few periods of sub-VFR conditions for Saturday. && .MARINE... Short Term /Through Wed/... As of 220 PM Tuesday...Increasing SSW winds expected to develop this aftn and cont into Wed ahead of approaching cold front. Winds will be mainly in the 10 to 20 kt range...however some gusts 20 to 25 poss at times espcly Pamlico Sound and outer waters. These winds will lead to seas grad building to 3 to 5 feet highest central waters. Long Term /Wednesday Night through Saturday... as of 35 AM Tue...The front should pass across the CWA between 06z and 12z Thursday with winds becoming N/NE at generally 10-15 knots with a few gusts to 20 knots possible. Seas of 3 to 5 feet Wed night will drop back to 2-4 feet for Thursday into Saturday. As high pressure strengthens offshore, winds veer to SE by Friday and become S/SW at 10-15 knots with a few higher gusts by Saturday. No Small Craft Advisories are anticipated for the extended period at this time. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...RF NEAR TERM...RF SHORT TERM...RF LONG TERM...CTC AVIATION...RF/CTC MARINE...RF/CTC
Office: RAH FXUS62 KRAH 222320 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 720 PM EDT Tue May 22 2018 .SYNOPSIS... A lee trough will linger over the srn middle Atlantic states ahead of a cold front that will settle southeastward into the area late Wednesday and early Wednesday night. Following high pressure will ridge south across the region on Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 400 PM Tuesday... A shear/trough axis evident from the Northeast swwd across the mid MS Valley and cntl Plains, and immediately preceding band of convection from the nrn middle Atlantic and lwr OH Valley swwd into the mid-South, will move ewd to the lee of cntl Appalachians through this evening. At the surface, a cold front was analyzed from a 1012 mb low over Lake Huron swwd across cntl OH and srn IL/MO. This boundary will move east to the srn New England coast swwd into MD and ern WV by Wed morning. An Appalachian-lee trough will meanwhile remain quasi- stationary over w-cntl NC. The aforementioned upstream convection centered over the cntl Appalachians and associated convectively-enhanced shear axis will drift east into cntl NC, likely in a weakening state owing to nocturnal stabilization, late this evening-early tonight. As such, some showers and storms may drift into the nrn and nwrn Piedmont through the first half of the night, before dissipating. Lows generally 65-70 degrees. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... As of 345 PM Tuesday... At the base of a mid-upr low migrating ewd across Hudson Bay and Quebec, a series of minor perturbations will sweep across the Northeast and middle Atlantic Wed, then offshore by Wed night. Mid- upr lvl flow will consequently strengthen slightly and veer to nwly over cntl NC, with effective bulk shear values likely to increase into the 25-30 kt range. At the surface, a cold front will settle swd, in backdoor fashion, across VA during the day, then into the nrn NC Piedmont very late Wed afternoon and evening, where it will overtake a preceding, quasi- stationary lee trough over w-cntl NC. The front, modulated by convective outflow, will settle swd through cntl NC overnight. A somewhat drier/lee humid/cooler air mass will follow, as post- frontal high pressure ridges swd across the middle Atlantic region. Initially scattered showers and storms are likely to focus along remnant outflow from convection from the previous day/night; and also along the lee trough. This activity is expected to become numerous by late afternoon and early evening, as convergence/lift increase with the arrival of the surface front. Storms are likely to become semi-organized in a multi-cellular storm mode along common outflow, with an associated strong to isolated damaging wind threat as storm clusters propagate sewd, with the relative greatest potential where the aforementioned bulk shear should be maximized over the nrn Piedmont and nrn Coastal Plain. The chance of showers and storms will linger overnight, particularly over the srn half of the CWFA, as the (effective) frontal zone settles swd. Any earlier severe threat will have diminished owing to both nocturnal cooling and prior convective overturning. Generally persistence temperatures in the mid-upr 80s are expected on average, though modulated and shortened by convection/clouds, with lows in the mid 60s to around 70 degrees. && .LONG TERM /THURSDAY THROUGH TUESDAY/... As of 235 PM Tuesday... Progressive high pressure over the Great Lakes will make a stab at drying us out, pushing a front south of the area early on Thursday. With the front along or south of the area, will have only small chance PoPs along the southern tier counties Thursday into Thursday night. Highs will be only mildly influenced by the front due to strong insolation and should reach mostly mid 80s. The high moves off the New England coast, with return flow beginning to spread into the west Friday into Saturday. As such, chance category PoPs in the west Friday taper off eastward, with all areas in the low chance category on Saturday as we sit beneath an upper ridge conducive to airmass thunderstorms in the resulting unstable, but weakly forced environment. Highs both days will mostly reach mid 80s after mild morning lows in the mid and upper 60s. The moisture transport from the south returns once again for the late weekend aided by the Bermuda high and a developing low pressure system in the Gulf of Mexico. The moisture return will increase precip coverage Sunday and into early next week, and while there is a lot of uncertainty as to the timing of forcing mechanisms driving heavier convection, it will be diurnally influenced, and will maintain high chance to likely PoPs Sunday through Tuesday. Highs will show little variation from previous days, mostly mid 80s, with morning mins in the soupier airmass closer to 70 each morning. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 720 PM Tuesday... Showers and storms, other than a few extremely localized downpours, have cleared central North Carolina by late evening Monday. Additional showers may be possible near to slightly after dark at INT and GSO, primarily related to the approach of a mid level trough and band of upstream convection now over the central Appalachians. Storm coverage is otherwise expected to remain isolated and/or of limited with decreasing coverage as the night continues. Similar to Tue morning, IFR-MVFR ceilings will be possible in the several hours centered around 12Z, with rising CIGs and eventually shower and thunderstorm development by Wednesday afternoon/evening. Outlook: Otherwise, another round of sub-VFR ceilings will probably result late Wed night-early Thu, owing to low level moisture convergence along and ahead of the aforementioned frontal zone. After relatively dry/VFR conditions Thu-Sat, moisture will increase by Sun-Mon, with resultant increasing probabilities of convection and morning stratus and/or fog during that time. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...MWS LONG TERM...mlm AVIATION...JJM/MWS