... Rain chances increase across the region through this evening as tropical moisture from Tropical Storm Isaias interacts with a stalling front. The storm is forecast to make landfall near the North Carolina and South Carolina border early tonight then cross eastern North Carolina late tonight. Our risk of heavy rainfall and isolated flooding will diminish as Isaias moves away from our region. A more typical summertime pattern of afternoon and evening thunderstorms will then return for the remainder of the week.
NEAR TERM /THROUGH TUESDAY/... As of 1035 PM EDT Monday: The latest RADAR mosaic is showing sct precip over the eastern half of the CWFA with most of the heavier rain bands associated with TC Isaias well to our east and southeast. With the heavy rain threat moving out of our fcst area, the Flash Flood Watch for the Northern NC Mtns was cancelled a few hours ago. Our eastern zones will likely get another 0.1 to 0.25 inches of rain before Isaias moves farther up the coast, but that's about it. Winds have also weakened over most sites as well, with the majority already reporting speeds of 5 kts or less. The main concern going forward will be any lingering high water on rivers and streams and the potential for widespread fog and/or low stratus overnight and tomorrow morning.
Otherwise, the remnants of TC Isaias will continue to move up the Atlantic Seaboard thru the period, as broad and deep upper trofing persists over much of the Eastern CONUS. At the sfc, TC Isaias is expected to be well to our NE by late tomorrow morning with very broad Canadian high pressure gradually spreading further south and east and over our area. The high will be slow to have much impact on the prevailing airmass with low-lvl winds still favoring a SWLY direction thru most of tomorrow. In addition, we retain a fair amount of low-level moisture and enough sfc-based CAPE to fuel scattered convection, especially over the higher terrain. However, profiles don't appear very conducive for strong to severe storms. A fairly early start is expected, but coverage should remain isolated to scattered, with the best coverage across the higher terrain and foothills. Temps should be close to normal.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 200 PM EDT Monday: As we move into the short term, the center of Isaias will be along the northern Mid-Atlantic coast and completely out of our hair. Deep upper trough centered from the Great Lakes down the OH/TN Valleys and to the Gulf will remain semi- stationary as the initial parent low lifts northeast but another shortwave dives down the back side, keeping the trough in place generally through the period. Expect a more typical pattern of diurnal convection, but enhanced by the lingering surface boundary that will be stalled across the area. A weak mid-level shortwave will push across the trough on Thursday, helping to enhance convective potential, and with boundary layer moisture remaining high, widespread likely pops seem reasonable. NAM remains, as usual, quite a bit higher with SBCAPE values both afternoons, but with the weak upper trough as well as the remnants of the surface boundary remaining in the area, cannot rule out isolated strong to severe in the afternoons. Temperatures will remain pretty close to normal.
LONG TERM /THURSDAY THROUGH MONDAY/... As of 215 PM EDT Monday: The upper trough will slowly push east and lift somewhat as we move into the weekend, with NW upper flow continuing through the end of the period, allowing a sequence of shortwaves to slide down into the area. Expect pops to mostly remain above climo values, though actual pops will be highly dependent on timing (which is currently uncertain) of the various shortwaves. Temperatures will remain fairly close to seasonal normals through the period.