Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 181932 AFDRAH AREA FORECAST DISCUSSION National Weather Service Raleigh NC 330 PM EDT Thu Jul 18 2019 .SYNOPSIS... An upper level disturbance will slowly cross the area today, before settling across southeast North Carolina tonight. A strong ridge of high pressure will build over the Mid Atlantic region from Friday through the weekend, bringing dangerous heat. A pattern change to cooler weather will arrive next week. && .NEAR TERM /THROUGH TONIGHT/... As of 250 PM Thursday... Scattered storms have already sprung up over western and north- central NC, translating cyclonically eastward following the mid level steering flow associated with the incoming weak shortwave trough. The latest surface analysis continues to feature a weak trough through the Piedmont. MLCAPE has already risen to 1500-2000 J/kg with D-CAPE of 900-1200 J/kg and low level lapse rates of 7.5- 8.0, all just slightly lower than yesterday`s values, but still supportive of scattered strong storms with downburst potential well into this evening, particularly given additional large scale forcing for ascent provided by the mid level wave, despite the poor deep layer shear. Will have high chance to low likely pops spreading W to E through the evening, with a gradual NW to SE downturn overnight as a subtle vorticity lobe shifts to our E. Based on this morning`s temps and statistical guidance, will have lows in the mid-upper 70s except lower 70s NW. -GIH && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 330 PM Thursday... Another dangerously hot day. The heat advisory will be maintained for the Coastal Plain and eastern Piedmont/Sandhills counties for Fri for heat indices of 102-107. The shortwave trough will weaken further as it shifts slowly to our E, while the surface trough holds over the CWA. As the high PW (>2") shifts into our SE half, the better convection chances should follow suit, and with MLCAPE peaking at 2000-2500 J/kg in this same area, will retain good chance pops in the E and S, peaking in the mid afternoon through early evening, before tapering down in the far SE overnight. Once again, the poor deep layer shear will limit storm organization and maintenance despite the potential for vigorous updrafts. Little change in the overall thermal profile is expected, with 850 mb temps still hovering near 19C, and surface dewpoints should remain solidly in the 70s. As such, the earlier issued heat advisory, an areal expansion from today`s, will be maintained. Given these successive days of hot weather with little recovery at night, the heat illness risk will be on the rise, even if peak HI values hold under 105F. Highs in the mid-upper 90s and lows 73-78. -GIH && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 320 PM Thursday... ...Excessive Heat Watch 11 AM Saturday through 11 PM Sunday evening for the eastern Piedmont, Sandhills, and Coastal Plain... More of the same as far as the heat is concerned for at least the first half of the long term forecast as the strong upper ridge remains anchored in place over the southeastern CONUS that will keep afternoon highs well into the 90s through Monday. Heat will reach potentially dangerous levels on over the weekend as heat index values could reach values higher then 110 degrees across the eastern half of the forecast area both Saturday and Sunday afternoons with heat indices in the western half of the CWA between 105-110 degrees. As such, an excessive heat watch is in effect from 11 AM on Saturday through 11 PM on Sunday. Everyone needs to take proper precautions if outside this weekend. There is an end in sight however to the oppressive heat as a very strong cold front will move southward through the mid-Atlantic states Monday and into the Carolinas on Tuesday, aided by a deepening upper level trough coming out of eastern Canada. Not only will this extinguish the extreme heat but also provide some quality rain chances as early as Monday evening for the Triad and through the day on Tuesday for the entire forecast area. As the front sinks south it will begin to slow and therefore a good amount of the area could see upwards of 2 inches of rain with the system with some localized areas, particularly in the southeast coming in with slightly higher values through Wednesday as the front hangs up along the coast. As far as post frontal temperatures are concerned, Tuesday afternoon highs should remain in the 80s across the board with low 80s north and high 80s to near 90 degrees in the south. By Wednesday afternoon, the cooler airmass continues to move in with highs generally in the low to mid 80s across the board. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 115 PM Wednesday... VFR conditions will dominate for the next 24 hours, outside of scattered showers and storms, which could bring a short period (likely under 1 hr in duration) of sub-VFR cigs/vsbys in rain. Gusts up to 40 mph may occur both in and near storms, including outflows that may spread well away from storms. The storm threat will peak late this afternoon through late evening, although southeast sections including FAY will see a storm threat lasting through around 08z. Isolated patches of MVFR or high-end IFR fog may form late tonight/early Wed morning near or over bodies of water, but these should not be widespread. Toward the end of the TAF valid period, after 16z, scattered storms may begin to develop near FAY. Winds will generally be from the SW around 5-10 kts with some gusts to around 12-15 kts the rest of this afternoon, then light/variable into Fri morning with a veer to the W and NW. Looking beyond 18z Fri, there is a good chance of late day storms Fri afternoon/night in the SE, especially 21z-06z. Shower/storm chances will decrease over the weekend, with a return to mostly dry and hot conditions for Sat-Mon, although storm chances will start to creep back up by late Mon and remain high through Tue. With isolated exceptions, the risk for early-morning sub-VFR fog/clouds through this period is generally low. -GIH && .CLIMATE... Record high temperatures and years for the next few days. RDU GSO FAY Thu 7/18 103/1887 97/1986 103/1942 Fri 7/19 101/1902 98/1977 101/2002 Sat 7/20 102/1942 100/1977 104/1932 Sun 7/21 102/2011 102/1926 105/1937 Mon 7/22 103/2011 101/1926 107/1932 && .RAH WATCHES/WARNINGS/ADVISORIES...Corrected. Heat Advisory until 7 PM EDT this evening for NCZ011- 026>028-041>043-077-078-085-086-088-089. Heat Advisory from noon to 7 PM EDT Friday for NCZ007>011-024>028- 040>043-075>078-085-086-088-089. Excessive Heat Watch from 11 AM EDT Saturday through 11 PM Sunday evening for NCZ007>011-024>028-040>043-075>078-085-086-088-089. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield SHORT TERM...Hartfield LONG TERM...Ellis AVIATION...Hartfield CLIMATE...CC is the U.S. government's official web portal to all federal, state and local government web resources and services.