Area Forecast Discussion
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FXUS62 KRAH 301951
Area Forecast Discussion
National Weather Service Raleigh NC
345 PM EDT Mon May 30 2016
.SYNOPSIS...The remnants of Tropical Storm Bonnie will slowly
meander northeast along the Carolina coast to a position near Cape
Hatteras by Thursday. A cold front will approach from the west
late in the work week as the remnants of Bonnie finally move
.NEAR TERM /Tonight/...
As of 315 PM Monday...
Latest surface analysis shows the remnants of Bonnie centered
just west of Myrtle Beach with an inverted surface trough extending
northeast of the center across the NC Coastal Plain. The surface
boundary was located near or just a little west of Interstate
95 with an east to southerly flow and dew points in the lower 70s
east of the trough and a northeast flow with dew points in the mid
to upper 60s west of the boundary. The visible satellite today shows
a transition from a more stable cloud pattern this morning to a
largely convective depiction as 18z MLCAPE values range from 500-
1000 J/KG across central NC.
Regional radar shows widespread showers and thunderstorms
along the NC coast associated with a plume of deep moisture
while more scattered showers along with a few thunderstorms
were slowly moving across the Coastal Plain, Sandhills and
eastern Piedmont. This convection is largely diurnally forced
with an enhanced western broken line or edge associated with 925-
850 hPa convergence and perhaps some weak upglide into the cool side
the surface boundary. Convection allowing models handle this trend
reasonably well although they have underdone the convective coverage
in the east. Scattered to numerous showers and isolated
thunderstorms will continue to lift northwest and north into
central NC during the remainder of the afternoon and evening. The
greatest convective coverage will be located near and east of U.S. 1
with precipitation chances and amounts significantly diminishing to
the west across the western Piedmont where the low level flow is more
divergent. Convection today should be efficient rain producers again
which combined with slow storm motion will lead to
quick accumulations of rain and a localized flooding concern,
especially in locations which had significant rain yesterday.
The convection should diminish in coverage and intensity during the
course of the evening with the loss of heating. Only isolated
showers are expected overnight, again mainly from U.S. east. Areas
of fog are likely to redevelop tonight with lows in the mid to upper
.SHORT TERM /Tuesday through Tuesday night/...
As of 345 PM Monday...
Not a lot of change in conditions are expected on Tuesday and
Tuesday night as the remnant low of Bonnie slowly meanders up the
Carolina coast. While the upper level trough across the carolinas
lifts somewhat on Tuesday and Tuesday night, the trough axis shifts
only ever so slightly east. The air mass across the region changes
very little with deep moisture persisting as precipitable water
values at or above 1.5 inches across much of the RAH CWA.
Accordingly, sensible weather conditions on Tuesday should be
similar to those of today with areas of morning stratus and fog
giving way to improving conditions with some breaks of sunshine,
especially in the western and southern Piedmont. Primarily
diurnally forced convection should redevelop on Tuesday, with perhaps
a subtly decrease in coverage with convection most widespread during
the afternoon and early evening. Showers and a few thunderstorms
will be most numerous across the northeast Piedmont and northern
Coastal Plain. Highs in the low-mid 80s, coolest east where clouds
should be thickest with greater shower coverage. Lows mostly in the
mid 60s. -blaes
.LONG TERM /Wednesday through Monday/...
As of 345 PM Monday...
A rather unsettled period expected as the remnants of Bonnie
slowly drift up the NC coast on Wednesday and Thursday. The
remnant surface low should move offshore on Friday as the western
Atlantic ridge weakens and an initial northern stream short wave
trough moves across the Great Lakes and Northeast on Friday and an
associated cold front drops into the Mid Atlantic. The result will be
a continuation of a fair amount of cloudiness and the threat of
mainly afternoon or evening scattered showers and thunderstorms.
Rain chances should decrease a bit on Wednesday into early Thursday
before ramping up again on Friday as the cold front approaches.
It will be muggy with highs in the lower to mid 80s on Wednesday
warming into the mid to upper 80s by Friday. Morning lows will range
in the mid to upper 60s.
Forecast confidence decreases for the end of the period as the
southern extent of the developing trough in the Plains closes off in
Texas on Friday into Saturday as the northern portion of the trough
deepens and slowly moves east over the weekend into Monday. A cold
front will linger across the area over the weekend before possibly
being pushed offshore on Monday. This will result in increasing rain
chances over the weekend with highs in the lower to mid 80s and lows
in the 60s. -blaes
.AVIATION /18Z Monday through Friday/...
As of 215 PM Monday...
Periods of adverse aviation conditions are expected across central
NC this afternoon and especially tonight.
The air mass across NC this afternoon is increasingly moist and
unstable from west to east as a plume of deep moisture extends
into eastern NC. Widespread LIFR and IFR conditions early this
morning in stratus and fog have improved to a mix of VFR and MVFR
ceilings. Scattered to numerous showers and isolated thunderstorms
will become more numerous this afternoon and lift northwest and north
in the circulation associated with the remnants of Tropical Storm
Bonnie. The greatest convective coverage along with a possible
thunderstorm is expected during the mid to late afternoon near and
especially east of U.S. 1 at the KFAY/KRWI/KRDU terminals where a
period of MVFR to IFR vsbys and cigs are possible. The coverage and
intensity of the shower and thunderstorms will slowly decrease during
the evening with precip chances low enough overnight to exclude a
mention in the TAF. Expect low stratus and fog to develop again
overnight, mainly after midnight with the greatest confidence of IFR
to possibly LIFR cigs and vsbys across the eastern Piedmont and
Sandhills including KRWI/KRDU/KFAY with slightly better conditions in
the Triad at KINT/KGSO.
Looking beyond 18Z Tuesday: Improving sky conditions are expected on
Tuesday as stratus lifts during the day with additional showers and
thunderstorms developing during the afternoon and early evening
Tuesday. Another period of sub-VFR conditions in fog/stratus expected
Tuesday night. A somewhat unsettled period of weather is expected for
Wednesday through Friday with a slight decrease in convective
coverage on Wednesday into early Thursday before increasing again as
a cold front approaches late Thursday into Friday. -blaes