Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 211916 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 315 PM EDT Sun May 21 2017 .SYNOPSIS... Weak high pressure will wedge south into most of central NC as the backdoor cold front temporarily stalls near the South Carolina border. The stalled front will lift back north-northeast as a warm front tonight, in advance of a cold front that will move into the region on Monday. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 315 PM Sunday... Near term models appear to have a good handle on a vort max and attendant shear axis lifting slowly north-northeast across northeast GA/northwest SC. This system interacting with a stalled front draped along the SC border into northwest NC and an abundantly moist atmosphere will cause showers and possibly a few thunderstorms to develop. The threat through 05Z appears to be greatest west of highway 1 and in particular, over the western-northwest Piedmont. along the western-northwest periphery of our CWA as the main upper support is projected to lift across western NC into sw Virginia. Will maintain low end likely PoPs for now but there is the potential for showers to be more numerous or persistent than forecast, leading to the possibility of categorical PoPs. Elsewhere, a few instability showers and storms are probable, primarily across the sandhills and coastal plain through mid evening. Abundant cloud cover and a light sfc wind slowly veering to a southerly direction will maintain mild/warm overnight temperatures. Min temps in the mid-upper 60s.
-- End Changed Discussion --
&& .SHORT TERM /MONDAY AND MONDAY NIGHT/...
-- Changed Discussion --
As of 315 PM Sunday... Unsettled weather pattern persist for Monday and Monday night. Lead mid-upper level vort max will continue to lift slowly northeast across southern VA Monday morning. This feature will provide enough forcing to cause a band of showers/isolated thunder to cross the northeast Piedmont/Sandhills and northern coastal plain during the morning hours. This feature should depart our region by mid day. Subsidence in its wake will likely suppress atmosphere enough to limit afternoon convection. Expect just isolated convection Monday afternoon-Monday evening. Next mid-upper level s/w will begin to influence the weather over our Piedmont counties Monday night with an increasing threat for showers and thunderstorms. The next s/w will move along a lingering surface trough stretched southwest-northeast over the western Piedmont. The increasing low level confluence along this boundary coupled with deep southwest flow will enhance the potential for training showers/storms along this feature, especially late Monday night into early Tuesday. Will maintain likely PoPs for now across the western Piedmont but if model trends continue, categorical PoPs will be necessary. A smaller than normal diurnal temperature trend will occur due to extensive cloud cover and morning showers in the east. Highs Monday upper 70s-lower 80s. Low temps Monday night generally mid-upper 60s.
-- End Changed Discussion --
&& .LONG TERM /TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
As of 235 PM EDT SUNDAY... Model consensus is a little better depicting a vigorous wave lifting out of the north central Gulf and riding deep southwest flow northeast into NC on Tuesday. Timing issues abound, however, as the GFS would like to lift the wave out a little further north and considerably (~9 hours) faster, which maintains a heavier rain axis west of the area, but cuts off the heavier rain abruptly Tuesday afternoon. Per its more consistency over the past couple of days, will maintain our ongoing ECMWF bias in the timing and QPF amounts, with categorical PoPs into Tuesday night and total rainfall amounts Tue-Thu in the 2.25-3 inch range. The bulk of the heavy rain (up to 2 inches) will fall Tuesday and Tuesday night and there will be a threat of flooding, particularly in our more urban areas, as the southwest flow and slow eastward translation of the system will encourage training convection. Strong low level convergence and low level jet of 40-50 Kts will be sufficient to produce strong storms, but severe potential will be diminished due to limited instability with the widespread antecedent cloudiness and weak mid level lapse rates...your basic high shear/low CAPE environment. Highs will range from ~70 northwest to mid and upper 70s in the coastal plain. Convection...particularly stronger convection...will diminish with loss of diurnal influence as the surface wave lifts north of the area early Tuesday night. However, southwest flow maintains relatively deep moisture transport overnight and through the day on Wednesday as a second cold front approaches from the west. As such, will maintain likely PoPs into Wednesday night, and we could see some pretty vigorous storms develop ahead of this second front on Wednesday afternoon as we will get some modest mid level cooling and drying behind the initial wave to steepen mid lapse rates. Will raise PoPs to the 60% range through the day, diminishing to a chance of showers Wednesday night into Thursday as we get dry-slotted by wrap- around from the cutoff low over the northern Ohio Valley. Highs Wednesday and Thursday will range from 75 to 80. Dryness returns at last on Friday and should persist through the weekend. Initial northwest flow flattens through the weekend, and the cool airmass moderates from the 70s Friday to the low to mid 80s Saturday and Sunday.
-- End Changed Discussion --
&& .AVIATION /18Z SUNDAY THROUGH FRIDAY/... As of 155 PM Sunday... There is a high likelihood of adverse aviation conditions across central NC through Tuesday as a series of upper level disturbances crosses the moist air mass in place across central NC. Each disturbance will kick-off scattered showers and thunderstorms with associated MVFR/IFR ceilings and visibilities. The first disturbance will cross central NC this evening through Monday morning. Another is expected to affect our region late Monday night into Tuesday. In between the periods of showers and storms, MVFR/low end VFR ceilings will prevail due to the available moisture in the atmosphere. The unsettled weather will persist through Wednesday. An improving weather pattern is anticipated by Thursday with VFR conditions highly probable for Thu-Fri. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...WSS/CBL NEAR TERM...WSS SHORT TERM...WSS LONG TERM..mlm AVIATION...WSS

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.