Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 301816 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 215 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 offshore. && .NEAR TERM /Today through Tonight/... As of 1050 AM Monday... Latest surface analysis shows the remnants of Bonnie centered near Myrtle Beach with an inverted trough extending northeast of the center across the NC Coastal Plain near interstate 95. To the east of this boundary a southeasterly flow is transporting rich moisture with dew points in the lower to mid 70s resulting in an increasingly unstable air mass with mlcape values now exceeding 1000 J/Kg across part of the central Coastal Plain. Regional radar shows isolated showers increasing in coverage and intensity across the Sandhills and Coastal Plain while a region of more widespread showers and storms across northeast NC shifts northward into VA. High resolution guidance pushes the surface trough across the Coastal Plain westward into the eastern Piedmont today. A vorticity maxima noted in WV imagery across southeast NC which is largely driving the larger area of showers in northeast NC will lift north this afternoon. Other than spurious vorticity maximums rotating about the deep cyclonic circulation associated with Bonnie, most of the convection today will be diurnally forced in a very wet, weak to moderately unstable air mass. The greatest convective coverage will be east of U.S. 1 with precipitation chances and amounts significantly diminishing to the west across the western Piedmont and Triad area where the air mass will be more stable and 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. While low level shear values are weak and storm organization will be limited, convective cells approaching the surface boundary will need to be monitored for enhanced, albeit short lived rotation. Highs today will be largely a function of the position of the surface boundary and periods of sunshine outside of precipitation. Look for highs today to range in the upper 70s to lower 80s. The convection tonight should diminish in coverage and intensity with the loss of heating with just an isolated shower expected overnight, mainly across the Coastal Plain. Lows will range in the mid to upper 60s with areas of fog and stratus re-developing tonight. -blaes && .SHORT TERM /Tuesday through Tuesday night/... As of 310 AM Monday... The mid level shear axis will weaken further Tue and continue an eastward drift into eastern NC/SE VA, as the center of TD Bonnie drifts NE over the southeast coast of NC. With the shift of both the mid level shear axis and the inverted surface trough eastward into coastal sections, our rain chances Tue should be a bit lower than today with the best coverage shifting into our far eastern sections and at the coast. PW will remain anomalously high, above 1.5" mainly east of Highway 1, so despite the waning dynamic forcing for ascent, it won`t take much to generate scattered showers and perhaps a storm or two especially over the eastern CWA. Will retain cloudy to mostly cloudy skies east, although the western CWA could see some sunshine if the weak mid level low center shifts into eastern NC/SE VA early enough. Highs in the low-mid 80s, coolest east where clouds should be thickest with greater shower coverage. Lows mostly in the mid 60s. -GIH && .LONG TERM /Wednesday through Sunday/... As of 305 AM Monday... Wednesday and Thursday: Tropical Depression Bonnie will continue to churn off the North Carolina coast on Wednesday somewhere between Wilmington and Cape Lookout. With no steering flow in place the forecast remains status quo with the best chances for precipitation in the east but models also hinting at precipitation forming as the result of orographic uplift as northeasterly flow approaches the Appalachians. Therefore will carry chance of showers and thunderstorms everywhere. Hot and humid with highs in the upper to middle 80s and dewpoints in the mid to upper 60s. Lows Wednesday night in the mid 60s. Thursday will see the depression move a bit further northeast and thus central NC may see a bit of a lull in precipitation before the next system approaches from the west. Will carry low chance pops in the forecast but it is possible that precipitation isn`t realized until later in the day as moisture transport ahead of the front increases. By evening expect thunderstorms to become more numerous in the Triad and points west. These will be driven mostly by diurnal heating as any dynamics associated with the fronts parent low will reside well to the north. Highs still in the mid 80s with lows in the mid to upper 60s. Friday through Sunday: Low pressure moving through the Northern Great Lakes and into Ontario and Quebec will move a frontal zone over the east coast and leave it there as it detaches and heads northeast. Back to the southwest an upper level low developing over Texas will help to initiate the development of a broad upper trough that will drape itself over the eastern US for several days. At the surface a couple of waves, most notably on Saturday afternoon, will move along the front and supply extra forcing for showers and thunderstorms over central NC. Expect best chances in the afternoon each day. Temperatures will cool off some during this time starting in the mid to upper 80s on Friday afternoon down to the lower 80s by Sunday afternoon. Lows each night in the mid to upper 60s. && .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 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...blaes NEAR TERM...blaes SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...blaes is the U.S. government's official web portal to all federal, state and local government web resources and services.