Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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649 FXUS62 KRAH 031152 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 752 AM EDT Mon Jun 3 2024 .SYNOPSIS... A series of mid-level disturbances will move east and interact with a surface trough and unseasonably moist airmass over NC through Thursday. && .NEAR TERM /THROUGH TONIGHT/... As of 400 AM Monday... Amid an unseasonably moist airmass characterized by PWs around 1.5" (~90th percentile at GSO), a tropopause-based disturbance will move from cntl SC esewd and offshore through 12Z. Meanwhile, an MCV evident in KRAX data over wrn Chatham Co. will drift slowly, generally ewd and across the ne NC Piedmont this morning/through ~16Z and across the Coastal Plain this afternoon/through ~20-21Z. At the surface, high pressure centered near Bermuda will continue to extend wwd and across the South Atlantic states. Meanwhile, a lee trough will sharpen with diurnal heating over the Foothills and wrn Piedmont of the srn Middle Atlantic and Carolinas, while a sea breeze will move inland and into the NC Coastal Plain and ern Sandhills. A weak backdoor cold front will drift south and across the Delmarva and Chesapeake Bay tonight. While cloud tops have generally been warming with the area of convection now moving across west-cntl NC, bursts of cooling and deepening convection have been noted immediately surrounding the center of the aforementioned MCV, as it moves east through a weakly unstable environment over cntl NC. This compact area of convection will probably be maintained as the MCV continues to move slowly ewd through the day, and the airmass diurnally warms into the lwr-mid 80s and becomes moderately unstable throughout cntl NC. In the wake of the MCV, additional, isolated/widely scattered showers/storms are expected to develop along the lee trough and spread east and across the wrn Piedmont later this afternoon-evening. A lack discernible forcing features for tonight suggest today`s convection should dissipate with nocturnal cooling, with seasonably muggy low temperatures in the mid/upr 60s. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 350 AM Monday... A lack of a synoptic forcing mechanism makes any details for Tuesday`s forecast difficult, but precipitable water values will be so high (GFS shows between 1.5-1.8") that any lift that does occur should be able to develop showers/thunderstorms (with CAPE values between 500-1000 J/kg). Models have shown the potential for a back- door cold front entering the area, but this remains tenuous. In addition, flow is less than 20 mph throughout the vertical column, so any showers that do develop will be slow-moving in nature. After a dry morning, have gone with chance pops in the afternoon and evening, with at least slight chance pops lingering into the overnight hours. Any flow in the vertical column that does occur will have a southerly component, and this weak warm advection should push highs into the mid/upper 80s. Tuesday night`s lows will be in the mid/upper 60s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 350 AM Monday... By Wednesday morning, a stacked low will be over Manitoba, with an upper trough and surface cold front arcing southeast across Minneapolis into Illinois and down across the southern Mississippi River. Both of these features will approach North Carolina during the day, and have expanded likely pops across the entire forecast area on Wednesday. Southerly flow will continue to increase, and the GFS indicates that PW values could approach 2", nearing record territory. High chance pops will continue into Wednesday night, with a lobe of energy breaking off both the surface and upper features and another stacked low forming near Lake Huron by Thursday morning. Slightly expanded the coverage of likely pops on Thursday, now covering all areas southeast of US-1, although models are showing some indecision in how quickly the cold front will move through. While some parameters depict the front moving east late Thursday into Thursday night, other parameters show the front bisecting the region somewhere along the US-1/I-95 corridor Thursday night with a more definitive push through the region Friday morning. Have continued with the slight chance pops everywhere Friday afternoon based on ensemble solutions despite deterministic solutions showing all precipitation moving to the coast. Dry weather returns to the forecast for the start of the weekend with dry conditions forecast Friday night, Saturday, and Saturday night. Another front should remain west of the region on Sunday, and with a lot of model uncertainty, only have slight chance pops in the forecast for Sunday. Thursday should be the warmest day, with highs ranging from the mid 80s to the lower 90s. The Thursday/Friday will only drop temperatures by a couple degrees, but it will bring a noticeably drier air mass into the region. The weekend should have highs in the 80s. Lows will mostly be in the 60s, with some upper 50s near the Virginia border Friday and Saturday nights. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... As of 750 AM Monday... A mid and upper-level disturbance, and accompanying rain and embedded showers/storms and flight restrictions, will move east across RDU, FAY, and RWI this morning. In their wake, an area of IFR ceilings at INT/GSO should lift and scatter to VFR by ~14-15Z. Otherwise, and elsewhere, daytime heating of a seasonably humid airmass may support a brief period of convective cloud bases between 2-3 thousand ft AGL through early this afternoon. Associated cumulus will probably deepen into scattered showers/storms with continued heating and destabilization through the rest of the afternoon, but nebulous and/or low predictability forcing mechanisms suggest probability of occurrence at any particular TAF site will be just 20- 30 percent at this time range. Areas of IFR stratus will be possible again late tonight-Tue morning, mainly over the Piedmont. Outlook: Seasonably humid conditions will support a risk of late night-early morning stratus and fog and mainly diurnal showers/storms through at least Thu, after which time a late week cold frontal passage, and following drier air, should end the threat of both. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...Green LONG TERM...Green AVIATION...MWS