Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/11/18

Area Forecast Discussion
National Weather Service Charleston SC
1027 PM EDT Thu May 10 2018 .SYNOPSIS... Unseasonably warm Atlantic high pressure will prevail across the region through the weekend. An upper level disturbance is expected to bring unsettled weather to the region beginning Monday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 1020 PM: KCAE Doppler Radar detected the cold pool/outflow was outpacing the convection across the midlands of SC. As a result, the convection was steadily weakening. However, an old seabreeze was located on 10 to 15 miles to the east of the advancing cold pool. If the boundary collision occurred a few hours ago I would expect new updrafts to develop over the boundary intersection. SPC mesoscale indicates that the low levels of the atmosphere have become quite stable. I will not forecast additional convection. SCHC PoPs will highlight the passage and eventual dissipation of weak showers through 1 AM. As of 755 PM: Sfc observations and regional radar composite indicated that the leading edge of a cold pool was sliding east across the midlands of SC. A few thunderstorms were along and just west of the cold pool. However, a seabreeze was clearly located on KCLX from Bulloch to Allendale Counties, pushing inland. SPC mesoanalysis shows very stable conditions across SE SC and GA. I will anticipate the convection to largely dissipate upstream of the forecast area. However, I will expect a few dissipating showers to move over the inland SC counties before completely ashing out. I will add SCHC PoPs for late this evening. As of 555 PM: KCLX detected an isolated thunderstorm over and south of Sapelo Island. SPC mesoscale analysis showed a pool of 1000 J/kg of CAPE along and west of an advancing seabreeze. East of the seabreeze, CIN values have increased to 15-25 J/kg. GOES-16 visible indicated on shallow Cu across the inland forecast area, with coverage gradually decreasing from the east. Given the trends and the time of the day, I will indicate SCHC PoPs only for the area of ongoing convection. Latest run of the HRRR shows the convection over the foothills and Piedmont generally dissipating during the mid evening across the Fall Line of the Carolinas. Previous Discussion: This Evening and Tonight: A few showers will continue for the next hour or two over parts of Southeast Georgia where sufficient instability remains near a seabreeze circulation. Showers will likely track slowly east, but diminish and/or dissipate while encountering a slightly cooler marine layer and the loss of diurnal heating with the approaching sunset. The main issue during the overnight period will deal with convection that has developed in the upstate. A mid/upper trough along with sfc lee trough over the Midlands should help push convection toward inland areas during overnight hours, but most if not all convection will likely have a tough time reaching parts of Southeast South Carolina as instability wanes. A dry forecast remains in place after sunset and through the overnight period, but a few showers can not be ruled out before the night is over, mainly well inland in Southeast South Carolina. Low temps will remain mild tonight, suggesting the overall threat of fog being low tonight. Low temps should dip into the low/mid 60s inland to upper 60s along the coast. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... High confidence this period with unseasonably warm Atlantic high pressure expected to continue. Increasingly warm and muggy conditions are likely through at least Saturday, although rain chances will be very low given the limited moisture, mainly confined to inland areas during the afternoon each day. Temperatures should top out in the lower to mid 90s during the afternoon away from the locally cooler coastal areas. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Models have started coming into a somewhat better agreement for the long term. An upper level low and surface low will be over the northeastern Gulf of Mexico Monday. Meanwhile, a front will be far to our north. The lows will move ever so slightly northward Tuesday, merging with the front by Wednesday. The flow around the lows will bring showers to our area Monday through Wednesday. There are still differences in the models regarding how much rainfall and when, so expect more adjustments going forward. For now, we have POPs increasing Monday through Wednesday. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... VFR conditions are expected to prevail at KCHS and KSAV through 0z Saturday. Extended Aviation Outlook: Mainly VFR through the weekend except low chance for restrictions from low clouds/fog each morning near daybreak. Better chance of restrictions after Sunday from low clouds and rain. && .MARINE... This Evening and Tonight: Sfc high pressure over the coastal waters will slide south while a weak mid/upper trough of low pressure passes aloft. As this process unfolds, a fair gradient will persist near the coast between the lee trough inland and high pressure over coastal waters. In general, south winds should peak near 15 kt this evening, especially near coastal locations. Winds should then slightly veer to southwest and remain at or below 10-15 kt overnight. Seas will range between 2-4 ft, highest in offshore Georgia waters. Friday through Tuesday: Atlantic high pressure will prevail through the weekend before weakening early next week. Overall no significant concerns expected. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...RJB LONG TERM...MS AVIATION...NED/RJB MARINE...DPB/RJB
Area Forecast Discussion
National Weather Service Des Moines IA
629 PM CDT Thu May 10 2018 ...Updated for 00z Aviation Discussion... .SHORT TERM.../Today through Tonight/ Issued at 340 PM CDT Thu May 10 2018 The frontal boundary was south of Iowa across northern Missouri at 18Z with a surface ridge extending south into northern Iowa. Aloft, an upper low will drift southeast into the central Rockies by Friday resulting in split flow across the central US. Iowa should be influenced by the southern stream in the split flow pattern with shortwaves ejecting out across the plains into early next week. The before mentioned surface boundary from the plains east across northern Missouri/southern Iowa will remain quasi- stationary. For tonight...thunderstorms should develop across the western plains and then move ese tonight. The latest HRRR run moves a MCS east across Nebraska reaching the Missouri river after midnight. In the meantime, strong moisture transport over the surface frontal zone and very good isentropic lift should result in elevated thunderstorm development across northern Iowa by late evening. The showers and thunderstorms over Nebraska should reach central Iowa after 09z and persist into Friday morning. .LONG TERM.../Friday through Wednesday/ Issued at 340 PM CDT Thu May 10 2018 .../Friday through Monday/...Confidence: Medium Once the MCS activity and elevated storms over northern Iowa diminish Friday morning, we should see a minimum in precipitation coverage Friday afternoon with cloudy and cool weather north of the surface boundary for all but the southern two rows of counties in Iowa. In southern Iowa, the surface front may drift into the area which would result in much warmer conditions. This is the reflected in the current forecast but confidence is not high. The NAM/GFS (12Z) both suggest warm air advection over the boundary around 700 mb resulting in a strong cap over the frontal zone Friday afternoon. Without any significant forcing, the cap looks strong enough to inhibit surface based convection Friday afternoon. However, the low-level jet over the boundary may initiate thunderstorm development Friday night. For the weekend, with the surface boundary in place, periodic shortwaves move through the SW flow aloft and abundant moisture, low-medium POPS look reasonable through the period with below normal temperatures Saturday and near normal on Sunday. .../Monday Night through Wednesday...Confidence: Low to Medium A split flow upper air pattern remains in the long-range with Iowa in the southern sw flow regime. In addition, the Gulf of Mexico remains open with moisture intersecting the surface boundary in, or near, Iowa. This upper air pattern favors unsettled weather over Iowa and POPS remain for several in place for several days. Temperatures will remain dependent upon cloud cover, precipitation coverage, etc. and generally near normal. && .AVIATION.../For the 00Z TAFS through 00Z Friday evening/ Issued at 631 PM CDT Thu May 10 2018 Light showers over northern Iowa will pass through early this evening and then the focus is on thunderstorms moving in later tonight. -TSRA included for most likely time of storms with MVFR restrictions, though refinements to impacts expected in next TAF issuance. There should be a lull in showers and storms by late morning, but low ceilings will linger through the end of the period at all but OTM. IFR ceilings at MCW may extend farther south to ALO and FOD, but lower confidence in those locations so left at low end MVFR. && .HYDROLOGY... Issued at 340 PM CDT Thu May 10 2018 Flood watches remain in effect of parts of the Cedar and Des Moines rivers in northern Iowa due to QPF driven rises Friday. Given the synoptic pattern, hydrology will remain a concern for the next several days especially over northern Iowa. Looking at the precipitable water values, Iowa will have values at or above 150 percent of normal into next week. Thunderstorms in this environment should be proficient precipitation producers. People which interests along the rivers should remain alert for the next several days. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Johnson LONG TERM...Johnson AVIATION...Ansorge HYDROLOGY...Johnson
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1007 PM EDT Thu May 10 2018 .SYNOPSIS... A weak cold front will push through the area late tonight into early Friday. High pressure will build in from the west into the weekend. A weak cold front will approach the area early next week. A trough of low pressure will impact the region mid to late next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 10 PM Thursday...Convection has moved into the nrn and wrn tiers as expected. Had one svr storm earlier but overall trend seems to be grad weakening with loss of heating. High res HRRR rapidly diminishes remaining storms in next cpl hours so will maintain likely pops inland and N a bit longer than expect to see activity weaken as it tries to move twrd srn cst. After about 06Z expect bulk of shra to be over with grad clearing. May see some patchy fog try and form as winds go light espcly where it rained. No change to lows with 60s area wide. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... As of 315 PM Thursday...As upper heights build across the region, a west to northwest downsloping flow will lead to slightly lower dewpoints on Friday and consequently warming temperatures as highs reach the mid/upper 80s inland, low/mid 80s south coast and mid/upper 70s Outer Banks. Skies will be sunny making for a near perfect May afternoon. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... As of 3 AM Thu...Above normal temps expected through the period, with increasing precip chances next week. Friday Night through Sunday...Above normal temps expected this weekend with mostly sunny to partly cloudy skies, as an upper ridge strengthens across the area with surface high pressure in control. Right now Sat looks like the warmest day with highs around 90 degrees inland, and 80-85 degrees along the coast. Some guidance shows highs in the low 90s inland Sat. Sun looks very similar to Sat, with a few more clouds. Overnight lows in the 60s. Ridge will likely suppress most convection, but isolated diurnally driven, seabreeze showers and tstms will be possible inland Sat afternoon/evening and again Sunday. Monday through Thursday...Below avg confidence in forecast specifics early next week, with decent amt of model spread. A weak backdoor front is forecast to approach the area Monday and Tuesday. The GFS keeps the front stalled to the north, while the ECMWF pushes the front further south late Monday and Tuesday before lifting back to the north Tue night. This could aid as a focus for convection. Models continue to develop a stacked low over FL and the Gulf of Mexico Monday and Tuesday. Given the front in the vicinity early next week and increasing moisture around the low and off the Atlantic, will continue chance pops. At this time looks like the best chances for widespread precip will be mid to late week, as low gets absorbed and moisture overspreads the area. Highs inland in the 80s and mid 70s/low 80s along the coast. Overnight lows in the mid to upper 60s. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term /Through Friday/... As of 615 AM Thu...Expect VFR to dominate however will have to watch line of storms that could lead to brief sub VFR later this evening espcly inland and N where could also see a stronger gust or two. After threat of convection pass after midnight cant rule out some patchy light fog or low clouds espcly if it rains, however most guidance not showing much so will keep as VFR. VFR conditions will prevail Fri with mclr skies with zonal flow aloft behind very weak cold front/trof. Long Term /Friday Night through Tuesday/... As of 3 AM Thu...Pred VFR conditions expected through the period. Patchy fog/stratus will be possible Sat and Sun mornings, and isolated diurnal showers/storms possible Sat and Sun afternoons. Precip chances increase next week with better chances for sub-VFR conditions. && .MARINE... Short Term /Through tonight/... As of 615 PM Thursday...Fcst looks good with SSW winds 10 to 20 kts this evening ahead of weak cold front/trof. Winds will diminish and become more W late. Prev disc...With advancing weak cold front and mid- level trough, winds will be SW 10-20 knots through the evening into tonight before diminishing toward morning. The winds become more W/NW behind the front Friday morning at 5-10 knots before becoming NE Friday afternoon. Seas are currently 3-4 feet and may get as high as 5 feet, especially late this evening into the early overnight hours, before dropping back to 2-4 feet for Friday per latest NWPS/SWAN model. Long Term /Friday Night through Tuesday/... As of 3 AM Thu...Looks like a nice day Sat with S winds 5-10 kt early increasing to 10-15 kt in the afternoon with seas 2-3 ft. SW winds 10-15 kt Sun, increasing to 10-20 kt Sun evening and into Monday with seas 2-4 ft. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...CTC NEAR TERM...RF SHORT TERM...CTC/BM LONG TERM...CQD AVIATION...RF/CQD MARINE...RF/CTC/CQD
Area Forecast Discussion
National Weather Service Morristown TN
914 PM EDT Thu May 10 2018 .DISCUSSION...Earlier convection has moved out of the area. However, some weak short wave energy is helping to force convection over KY to our northwest, and both the NAM and HRRR indicate this will affect parts of our northeast after midnight. Will add some low PoPs to allow for this. Will also make some adjustments to sky cover, hourly temps, and dew points. update out soon. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 64 89 65 90 / 20 20 10 10 Knoxville McGhee Tyson Airport, TN 63 87 64 88 / 20 20 10 10 Oak Ridge, TN 62 88 64 89 / 20 20 10 10 Tri Cities Airport, TN 58 84 61 87 / 20 20 10 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday) Issued at 318 PM CDT Thu May 10 2018 This afternoon an upper level trough was over the western states while ridge was located over the Plains. Low pressure was located in the lee of the Rockies while a warm front was located north into Nebraska. There was a piece of energy moving northeast across COlorado into Wyoming. Atmosphere across northern Kansas remains capped to surfaced based convection in the presence of a stout EML. Temperatures have warmed into the mid and upper 80s this afternoon. Tonight models continue to show best forcing for elevated convection to remain north into Nebraska. CAMS, particularly the NMM and the HRRR show the Nebraska convection moving across northern Kansas along the border after 05Z tonight then moving off to the northeast late in the night as the low level jet increases advecting moisture northward into Iowa where favorable moisture transport will exist for MCS maintenance. Any elevated storms tonight will have the potential to produce strong wind gusts along with hail. Winds will increase later tonight as the low pressure in Colorado moves eastward into western Kansas. Forecast soundings show lower boundary layer will remain mixed and low temperatures will cool into the mid and upper 60. On Friday, the surface low is forecast to move out into central or southwest Kansas with a frontal boundary extending from Iowa southwest into southwest Kansas. During the afternoon hours The front is forecast to bisect the cwa from southeast Nebraska to near Salina or McPherson after 21Z. Forecast soundings continue to show a stout EML in place through the daytime hours. Convergence along the surface front is fairly weak and will likely not be enough to overcome the cap to initiate surfaced based convection. If a storm were to develop it would likely be storing to severe as 0-6km shear increases to 30 to 50 kts after 21Z and MLCAPE in excess of 2500 J/kg. Friday will be another very warm day as temperatures rise into the upper 80s to mid 90s. .LONG TERM...(Friday night through Thursday) Issued at 318 PM CDT Thu May 10 2018 For Friday night through Sunday, models continue to show a fairly strong elevated mixed layer (EML) over the forecast area capping the boundary layer. Meanwhile forcing is not that obvious with maybe some subtle waves aloft. Models also show heights generally rising through the weekend and low level convergence along the surface trough does not look that strong. The GFS seems to be one of the only solutions with much QPF over the forecast area and think given the factors working against convection that it may be overdone. In general I prefer the idea of the NAM/ECMWF with any MCS Friday night remaining north across NEB. Nevertheless have maintained a small chance for storms across the northern half of the forecast area. Precip chances Saturday may be tied more to whether diurnal heating and low level convergence can overcome the EML. Again with forecast soundings showing the cap holding, the forecast only has some 20 to 30 percent chance POPs. For next week, models show the EML weakening as southwest flow aloft continues. A moist and conditionally unstable airmass is progged to remain over the area through at least the first half of next week. So the forecast continues with some chance POPs through Tuesday. There are some differences between the GFS and ECMWF by mid week with the ECMWF trying to bring a weak surface ridge into the area by Thursday. Confidence in these mesoscale details is not that great this far out so have continued with some chance for showers and thunderstorms through the end of the forecast period. There doesn`t look to be much change in temps over the next several days. Models suggest the thermal ridge may still be holding on across east central KS on Saturday with highs in the lower 90s. But in general temps look to not very much from highs in the 80s and lows in the 60s. The one question mark is the potential for some stratus to move into parts of north central KS Saturday and Sunday. This could hold temps in the 70s if the low clouds hold in strong. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 636 PM CDT Thu May 10 2018 VFR conditions are expected for the TAF period with a slight chance of high-based showers and storms tonight. However, confidence in this precip was not high enough to mention in the 00Z TAFs. Southerly LLWS develops around 04Z and persists for the night, with gusty southerly surface winds increasing Friday morning. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...53 LONG TERM...Wolters AVIATION...Skow