Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 190044 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 845 PM EDT Sun Jun 18 2017 .SYNOPSIS... A warm, moist, and unsettled air mass will remain in place through Monday. A cold front will move slowly into the area from the northwest Monday night through Tuesday. && .NEAR TERM /Today through tonight/... As of 230 PM Sunday... A later start to convection today as opposed to yesterday as low cloud cover remained a player through the morning. As far as the environment is concerned, we once again have about 2000 J/Kg of MLCAPE to work with but a little less well defined surface trough. There is a bit of low level convergence in the SW piedmont and this is where the first convection of the afternoon has indeed formed. PW values are much drier than previous days Flow has picked up so storms are moving at a better clip than they were the last few days. Therefore don`t see heavy rain as big of a threat as it has been. Forecast soundings point out well the mid and upper level drying that has occurred. This how ever does mean that DCAPE values are a little higher than they have been in previous days. CAMs agree that coverage should certainly be less this afternoon. That being said the better environment for wind means that what does form could have a better chance of being accompanied by damaging wind. Hail is still very unlikely with freezing levels near 14 kft and not much in the way of updraft support. After sunset, convection should end fairly quickly. Highs today topping out in the upper 80s to low 90s. Tonight expect low stratus to form across the area with IFR/MVFR ceilings likely. Low temperatures in the low 70s. && .SHORT TERM /Monday through Monday night/... As of 230 PM Sunday... Low pressure over the Great Lakes will help to move a cold front closer to the area on Monday. This will cause an increase in precipitation chances Monday afternoon and evening as moisture transport increases ahead of the front, combining with diurnal heating to bring chance to likely PoPs into the region late Monday and early Tuesday. Lift will be aided by the right entrance region of an 850 mb jet over the northern portion of the CWA. This will be coupled with the greatest mid-level vorticity moving through the CWA during peak heating hours. The best upper level dynamics will stay well to the north of the area however, making this a good, but not great setup for severe weather. The day 2 outlook from SPC has a slight risk for severe weather in the northwest piedmont with a marginal risk across the rest of the CWA. The most likely threat will be damaging winds with storm mode likely being multi-cellular or line segments based on bulk shear values of 20-30 kts. While some organization to storms is possible, hodographs are not particularly conducive to rotation and 0-1 km shear and helicity are both fairly low at 10 kts and less than 100 m2/s2 respectively. While freezing levels remain high, better organization of updrafts could mean some better chances for severe hail but still much less likely than severe wind. Expect precipitation to continue through Monday night and into Tuesday as the front slows to a crawl. This will keep good rainfall chances in the forecast through the middle of the week. High temperatures Monday in the mid to upper 80s with lows in the upper 60s to lower 70s. && .LONG TERM /TUESDAY THROUGH SUNDAY/... AS OF 300 PM Sunday... Tuesday and Wednesday: The upper level trough that has persisted west of the region will slowly progress eastward, swinging over Central NC Tuesday and Wednesday. Continued deep south-southwesterly flow will result in a persistent moist airmass over the area through Wednesday. Showers and thunderstorms with the general diurnal nature will continue, best chances in the aft/eve and lowest overnight. The surface trough/front axis will stall over NC through Wednesday as well, with the possibility of a lull in convective activity, though the chance for convection east of the boundary will still exist. Highs in the low to mid 80s and lows in the mid 60s to near 70 degrees. Thursday through Sunday: A good deal of uncertainty still exists for this part of the forecast and the evolution of a tropical low over the Gulf. Where the low develops and subsequently moves will have a large impact on the weather for Central NC through the rest of the extended period and given the significant differences between the medium range models, will hold off on specifics for now. The southwesterly flow should persist and thus expect continued climatological chances for showers/thunderstorms through the period. Highs in the mid to upper 80s Thursday and Friday, and upper 80s to low 90s for the weekend. Lows in the low to mid 70s will persist through Saturday night. The models do come into a bit better agreement with the overall pattern toward the end of the period. A cold front will approach from the northwest Sunday and Sunday night, which could bring a reprieve from the heat and humidity early next week. && .AVIATION /00Z Monday through Friday/...
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As of 845 PM Sunday... 24 Hour TAF period: Stronger diurnal showers and storms have weakened with sunset, but approach of a short wave in the deep southwest flow will continue to spawn widely scattered showers and a few storms overnight. Won`t be including in the TAF`s as timing is very low confidence as well as the small number of showers making it unlikely that the airports will see one breeze through. Do expect a recurrence of stratus after midnight in the muggy airmass. Pressure gradient will hinder development of fog, and the height of the stratus deck is expected to be around the 1000 foot IFR/MVFR changeover point. Showers will begin to ramp up fairly early in the west ahead of an approaching front tomorrow, with fairly good coverage of thunderstorms at the GSO/INT sites by early afternoon, and a couple of hours later (20-21Z) over eastern sites. Can`t pin down a high-confidence window of thunder at this point, and will have VCTS in the TAFS for the final 6 hour (18-00Z) time frame. Long term: The front approaching central NC tomorrow will linger in the area, most likely over the east, through Wednesday. Uncertainty surrounding a low pressure center coming out of the Gulf of Mexico leaves a low confidence forecast for the end of the week.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Ellis SHORT TERM...Ellis LONG TERM...KC AVIATION...MLM

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