Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/20/20

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
640 PM CDT Wed Aug 19 2020 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...VFR conditions are expected through the next 24 hours. Leftover convective cirrus this evening will fade to cumulus tonight and through tomorrow. Light winds overnight will become moderate during the daytime. && .PREV DISCUSSION... /issued 301 PM CDT Wed Aug 19 2020/ SHORT TERM (Tonight through Thursday Night): Currently, KBRO radar is indicating some isold conv firing over Zapata and Jim Hogg Counties with little or no movement. Daytime heating may help maintain this isold conv for a few more hours with the pcpn diminishing later this evening with the loss of the diurnal heating. The latest HRRR run maintains this spotty activity over the next few hours. Vsbl satl imagery doesn`t show much in the way of CU development at this time, so believe that the current conv should remain confined primarily to the western counties throughout the early evening hours. The short term NAM/GFS and ECMWF guidance shows relatively drier and more stable air pushing into the region throughout Thurs and Thurs Night. This should shutdown the conv chcs tomorrow afternoon and evening. So will go close to single digit pops throughout tomorrow and tomorrow night. With a relatively dry atms prevailing throughout the short term, expect high temps tomorrow to edge up a couple of degrees. The most recent short term temp guidance from the NAM/GFS/ECMWF are all in reasonably good agreement for maxes/mins through tomorrow night and will stick pretty close to this blend. LONG TERM (Friday through Wednesday):The mid-level pattern to start the long term period is in good agreement with the model guidance indicating ridging focused across the Desert Southwest while a large trough stretches from the Ohio Valley across the western Gulf of Mexico. With limited low-level moisture through Saturday, fair conditions are expected with temperatures at or slightly above average and generally rain free. The pressure gradient at the surface gradually strengthens, resulting in the return of a light to moderate onshore flow. The most active portion of the long term forecast concentrates during the early to middle of next week. The mid-level trough located over the western Gulf of Mexico is expected to gradually weaken and eventually lift out. With varying model solutions on how quick this process occurs, results in higher uncertainty on the evolution of the tropical wave across the Carribean (invest 97L). This disturbance continues to be closely monitored by NHC and continues to feature a high chance (80%) of developing into a tropical cyclone within the next 5 days. Additional uncertainty exists with the disturbance, in regards to how quickly the tropical wave may try to organize and consolidate into a low-level circulation, and how much impact could land interaction have on the disturbance. Overall, despite the models diverging with the location and intensity of the tropical wave (possible tropical cyclone) for early next week, will increase rain chances across Deep South Texas with the prospect for an incoming influx of gulf moisture. Some heavy rainfall could be possible but it remains too early for any discussion on rainfall amounts. Into the middle of next week, I have elected to continue to keep lingering rain chances in the forecast. We will also keep an eye on the progress of the tropical wave to the east of the lesser Antilles (invest 98L) as that tropical wave could advance into the eastern Gulf of Mexico, as a potential tropical cyclone as well. The increased moisture and cloud cover should help to lower tempeatures slightly for the early to middle portions of next week. MARINE (Tonight through Thursday Night)...Swell data from Buoy020 shows seas offshore at <1 foot with other surface obs near the coastline showing relatively light onshore winds. So marine conditions do not geet much better than this. However, the S-SE low level winds will likely return tomorrow as the PGF strengthens a bit due to a little stronger surface ridging across the Gulf of Mex. No SCEC/SCA conditions expected through Thurs Night. (Friday through Monday night): Light to moderate onshore winds along with low seas are expected Friday through the majority of the weekend with a modest but gradually strengthening pressure gradient. Seas will then gradually build late Sunday through the end of the forecast period as a tropical wave/low pressure system advances from around the Yucatan Peninsula into the Gulf of Mexico. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 75 95 77 94 / 10 0 0 0 BROWNSVILLE 76 98 78 97 / 10 0 0 0 HARLINGEN 74 99 77 98 / 20 0 0 0 MCALLEN 76 100 77 100 / 20 0 0 0 RIO GRANDE CITY 76 103 76 103 / 20 0 0 0 SOUTH PADRE ISLAND 80 88 81 89 / 10 0 0 0 && .BRO WATCHES/WARNINGS/ADVISORIES...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV
Area Forecast Discussion
National Weather Service Peachtree City GA
737 PM EDT Wed Aug 19 2020 .PREV DISCUSSION... /issued 348 PM EDT Wed Aug 19 2020/ SHORT TERM /Tonight through Thursday Night/... Primary concern in the short term period is heavy rainfall/ isolated flash flooding and diurnal convection. PW on KFFC morning RAOB was only 1.3in and 19Z RAP analysis 1.4in over all but far SE counties, yet deep convection in north GA so far today have been very efficient and moving just fast enough for some training/ redevelopment with favorable orientation and boundary interaction. PW progged to increase significantly to 1.75-1.85in this time tomorrow. Only hope for not seeing enhanced heavy rainfall and flooding threat is if clouds will diminish sfc heating and instability, which is a strong possibility. Vertical wind shear will be limited as well, so storms should be less intense Thursday. Guidance also indicating that convection Thurs night will persist past midnight, which is also very possible if deep moisture materializes to the extent forecast. Tried to modify max/min temps to decrease diurnal range but NBM max temps already quite cool tomorrow. SNELSON LONG TERM /Friday through Wednesday/... Wet weekend ahead as the long term picks up on Friday with stalled, sheared PV anomaly and associated 500 mb trough axis still to the west of the CWA. Broad ascent is forecast to continue to overspread the region focused in part by any vorticity maxima rotating around the trough as well as general WAA the the low levels which will also be bringing in plenty of gulf moisture. Models are supportive of likely or higher PoPs across the region both Friday and Saturday, though final coverage details may be influenced by mesoscale details, such as remnant outflow boundaries and leftover cloudiness from previous day`s/overnight convection, that courser global models won`t properly resolve. 700-500 mb lapse rates will remain rather lack luster on Friday, though ample day time heating and marginal shear will support some strong thunderstorm potential. Lapse rates improve a bit on Saturday as colder core of trough is expected to rotate through the CWA on its way to being absorbed within polar jet, making for somewhat better CAPE profiles and decent shear profiles, so some potential will once again exist for stronger thunderstorms across the area, though plenty of uncertainty remains with regards to timing as well as placement of aforementioned mesoscale features that could disrupt the larger scale set up. Trough begins to dissipate on Sunday as PV anomaly gets sheared out between large, persistent western ridge and another ridge sliding in from the Atlantic. Still, plenty of moisture will be wrapping into the CWA thanks to being on the western flank of that Atlantic ridge, so while PoPs may not be as prolific, still expect typical summer like coverage across the north, and possibly even better coverage to the south thanks to outflows and seabreeze type fronts. Similar situation on Monday, though more uncertainty begins to creep into the forecast. 12Z GFS shows tropical wave moving into the gulf during this time period. Location of this tropical wave will be highly dependent on how organized current system over the MDR of the tropical Atlantic becomes as well as details of the ridge sliding to the west over the Atlantic. Will carry this uncertainty in the PoPs, though still expect some coverage given tropical airmass will still be in place across the CWA. Lusk && .AVIATION... 00Z UPDATE... Line of TSRA sliding past ATL are terminals at this hour but still affecting AHN which will require a continued TEMPO group. Feel activity will remain north of CSG and MCN through this evening and will not include any mention of TS there. A brief period of IFR possible toward daybreak Thu and will continue the mention in the TAF. Have converted the predominant TSRA to SHRA for Thu afternoon and then a Prob30 for TSRA. Winds look to remain on the east side and generally light. //ATL CONFIDENCE...00Z UPDATE... Medium on IFR potential. High on remaining elements. Deese && .PRELIMINARY POINT TEMPS/POPS... Athens 68 84 68 81 / 50 80 80 70 Atlanta 69 83 70 80 / 60 80 80 70 Blairsville 63 78 64 74 / 50 80 80 80 Cartersville 68 85 69 80 / 60 80 80 70 Columbus 70 88 71 83 / 50 80 80 70 Gainesville 67 82 68 79 / 50 80 80 70 Macon 70 87 71 82 / 50 80 80 60 Rome 67 85 69 81 / 60 80 70 70 Peachtree City 67 84 69 79 / 60 80 80 70 Vidalia 71 89 72 85 / 40 70 70 60 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SNELSON LONG TERM....Lusk AVIATION...Deese
Area Forecast Discussion
National Weather Service Grand Rapids MI
731 PM EDT Wed Aug 19 2020 LATEST UPDATE... Aviation/Marine .SYNOPSIS... Issued at 242 PM EDT Wed Aug 19 2020 - Less risk for rain into the weekend - Turning warmer && .DISCUSSION...(This evening through next Wednesday) Issued at 242 PM EDT Wed Aug 19 2020 - Less risk for rain into the weekend Trends in the models keep the surface high pressure system over Southern Lower MI into the weekend. This will act to keep the frontal zone north of the CWA. Later Sunday and into Monday a weakening cold front tries to drop on down through the CWA...but the models show warm air advection returning on Tuesday. Thus any lift looks weak with this feature and POPs will be kept low for now. - Turning warmer Warm air advection strengthens over the next couple of days with the low level thermal ridge pulling in for Friday and Saturday. Temps at 850 mb reach the upper teens and that will support above normal temperatures. We could make a run at 90 those days...especially over interior parts of the state. Rather big differences show up next week with the High Res Euro drawing a significant low level thermal ridge in for the middle part of the week. Temps at 850 mb are shown to top 20 deg C Tue into Thu making 90s a possibility. The GFS is more conservative...about 5 degrees lower with the 850 mb temps. For now we will continue to feature above normal temperatures as the low level thermal fields continue to suggest ridging in the CWA. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 730 PM EDT Wed Aug 19 2020 Surface high pressure will continue to provide mostly clear skies tonight and light winds. It would not be out of the question for a little patchy fog as there was last night but given how sunny and warm it was today seems any fog would be rather limited. I did not put fog in any of the TAF but JXN would be the most likely to have fog if there were fog. On Thursday a warm front passes by well to our north, this may lead to some mid clouds in our northern TAF sites but otherwise expect southwest winds to develop around 10 knots. Winds will be stronger over the northern TAF sites than the southern TAF sites due the proximity of the warm front. Any associated convection will be well north of the GRR CWA. && .MARINE... Issued at 730 PM EDT Wed Aug 19 2020 I will issue both a Small Craft Advisory and Beach Hazard Statement for our northern 2 lake zones and adjacent county zones due to 3 to 5 foot waves and 15 to 25 knot winds late tonight into Thursday evening. Given the high high pressure ridge south of Michigan and the frontal zone over upper Michigan, the pressure gradient between those to features will allow for stronger winds over central and northern Lake Michigan. Looking at the NAMNEST, HRRR and ECMWF all showed winds in the range of 15 to 25 knots with gusts near 30 knots from around 06z tonight till after 00z Friday. This should build 3 to 5 foot waves and result hazardous beach conditions. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from 2 AM EDT Thursday through Thursday evening for MIZ037-043. LM...Small Craft Advisory from 2 AM to 11 PM EDT Thursday for LMZ848- 849. && $$ SYNOPSIS...MJS DISCUSSION...MJS AVIATION...WDM MARINE...WDM
Area Forecast Discussion
National Weather Service Medford OR
848 PM PDT Wed Aug 19 2020 .DISCUSSION...Satellite imagery is showing a few clouds here and there across southern Oregon and northern California with predominantly clear skies. Some of the fire weather imagery shows the Crane Fire near Lakeview being somewhat active. Overall humidities have started to rise and winds have started to decrease, so have allowed the Red Flag Warning to expire at 8pm. Overnight, mostly clear conditions are expected with maybe some advancing cloud cover associated with a weak frontal boundary. Overall, the forecast is in good shape; so no changes are needed at this time. -Schaaf && .AVIATION...For the 20/06Z TAFs...Along the coast and over the coastal waters...Areas of IFR cigs in marine stratus over the coastal waters will return to the coast this evening, getting into the coastal valleys tonight. The stratus will then burn back to the coast by Thursday afternoon, moving back onshore Thursday evening. Inland...VFR conditions will prevail across the area through Thursday, except for southwest Siskiyou County, which will see some reduced visibilities due to smoke from the Red Salmon Fire. Winds will be gusty east of the Cascades and in the inland valleys west of the Cascades for the remainder of this evening, and again Thursday afternoon and evening. && .MARINE...Updated 830 PM PDT Wednesday 19 August 2020...Relatively light winds and low seas will persist through Friday night. There will be periods of poor visibility in low clouds and fog. A weak front will move onshore Friday, then a thermal trough will develop near the coast. This will bring increasing north winds to the area beginning Saturday, with steep to very steep seas Saturday through Monday. && .PREV DISCUSSION... /Issued 317 PM PDT Wed Aug 19 2020/ SHORT TERM...Today through Sat. morning...Beginning in the west, current satellite shows marine stratus on the southern sides of Cape Arago and Coquille Point. South of Cape Blanco, marine stratus has thinned and lifted slightly, but buoy cameras from buoy 015 (off Cape Blanco) and 027 (just north Point St. George) show sunlight struggling to break though. With the lack of strong northerlies the stratus will remain in place and thicken overnight to a fog. To the east, satellite reveals a mixture of smoke and mid-level cloud over Sikiyou and Modoc counties in N. Cal. and in the SE portions of Klamath and Lake Counties. The latest HRRR smoke suggests that smoke related impacts will be light for most areas, except around Alturas in Modoc County. Around Alturas the HRRR smoke shows moderate amounts of surface smoke, but air quality issues should remain low. The fires to our north and south have enjoyed an active burning day, so we will continue to monitor smoke and air quality issues closely. The thickest smoke, from the S.F. Bay area, is being directed more NE towards Reno at the moment and is helping to limit smoke impacts in our area. Friday morning, a low off British Columbia will drag a front through our area. The recent dry conditions will not favor chances for much measurable rain as the front will struggle to penetrate the current airmass. However, GEFS and Ecmwf members have been holding on to rain further down the coast and is a sign that this is not a totally weak front. Yet, the only places expected to receive measurable rainfall are from Bandon north along the coast. Inland, it is not anticipated much rainfall will occur and have cut off measurable amounts along a line from Elkton to Myrtle Point. This still seems unlikely, but have added drizzle to the forecast along ridges in the coast range and as far east as Diamond Lake, where upslope flow may aid to wring out some moisture. May cut back on these areas if models dry out, but there are enough ensemble members with decent mid-level moisture to keep this element for the time being. Friday evening, the momentum from the front will carry the winds east of the Cascades, creating breezy surface conditions in valleys and along ridges. We will also experience cooler night time lows than have been recently occuring and is actually approaching the climatological norms in northern half of our forecast area, roughly from Medford north, excluding the Cascades east. -Miles LONG TERM...WITH THE FRONT DEPARTING, AREAS OF FOG COULD DEVELOP IN THE COASTAL VALLEYS AND INTO POINTS OF THE UMPQUA BASIN ON SATURDAY MORNING. THINGS START TO QUIET DOWN AFTER THE COLD FRONT MOVES EASTWARD AND DRIER AIR FILTERS INTO THE AREA DURING THE DAY ON SATURDAY. ZONAL FLOW ALOFT BEGINS TO TAKE SHAPE IN THE MID-TO-UPPER LEVELS OF THE ATMOSPHERE. THIS WILL KEEP TEMPERATURES RIGHT AROUND NORMAL FOR THIS TIME OF YEAR ACROSS THE AREA. TEMPERATURES WARMUP SLIGHTLY ON SUNDAY AND CONTINUE TO DO SO INTO NEXT WEEK AS A THERMAL TROUGH BEGINS TO SET UP SHOP ONCE AGAIN ACROSS THE SOUTHERN OREGON COAST. OUR FOCUS TURNS TO THE BEGINNING AND MIDDLE OF NEXT WEEK AS A TROPICAL SYSTEM WILL MOVE NORTH OUT OF THE TROPICS AND MAKE ITS WAY TOWARDS THE CHANNEL ISLANDS OFF THE CALIFORNIA COAST. SOME OF THE GUIDANCE HAS THE SYSTEM LOSING MOMENTUM AND SLOWING DOWN BECAUSE OF HIGH PRESSURE MOVING IN FROM THE WEST INHIBITING ANY FURTHER MOVEMENT. THERE IS STILL A LOT OF UNCERTAINTY IN MODEL GUIDANCE ON HOW MUCH THIS SYSTEM WILL IMPACT THE AREA. THAT BEING SAID, IF ANY EXTRA MOISTURE AND ENERGY MAKES IT TO THE REGION, SHOWER AND THUNDERSTORM CHANCES WILL INCREASE. WE WILL CONTINUE TO MONITOR THIS SYSTEM OVER THE NEXT SEVERAL DAY AS IT BEGINS TO MAKE ITS NORTHERLY TRACK. -ROGERS MARINE...Updated 200 PM PDT Wednesday 19 August 2020...Relatively light winds and low seas will persist through Friday night. There will be periods of poor visibility in low clouds and fog. A weak front will move onshore Friday, then a thermal trough will develop near the coast. This will bring increasing north winds to the area beginning Saturday, with steep to very steep seas developing over the waters Saturday through Monday. FIRE WEATHER...Updated 200 PM PDT Wednesday 19 August 2020... The main concern into this evening will be gusty winds and low relative humidity and a Red Flag Warning remains in effect for this until 8 pm pdt. An upper trough will move into the area later tonight and bring cooling for most interior locations Thursday and slightly higher relative humidities. Gusty winds are still expected both Thursday and Friday afternoon and evening east of the Cascades. Were not expecting Red Flag conditions to be met during this time, but it`s something we`ll likely highlight in the fire weather forecast. The threat for thunderstorms is zero through the weekend. Friday, a weak front will brush by north of our area, but could not rule out intermittent light rain in fire zones 615 and northwest 616, but amounts will probably be in the order of 0.01 to 0.03 of an inch of rain, if anything. The main effect will be cooler temperatures over most of the area and higher relative humidities in the afternoon. A west to southwest flow remains over the area Saturday into Sunday. However the four corners ridge will slowly inch it`s way into our area bringing a return to hotter temperatures and lower relative humidity. Winds during this time are not expected to be a concern (in terms of critical fire concerns). Monday will warrant close watching. We`ll be keeping a close eye on the track of Hurricane Genevieve. Because of the strong four corners ridge, the general consensus is for this to move northwest, then north up along the California coast by the start of next week. This could bring another round of moisture and increasing instability into the southeastern part of the area as early as Monday afternoon, thus increasing the threat for thunderstorms. Right now, we do not have anything in the forecast, but that does not mean the chance is zero. It`s a small chance. Part of the reason we have nothing in is because it`s still a long ways out and details are likely to change over time. -Petrucelli && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. Pacific Coastal Waters...None. $$
Area Forecast Discussion
National Weather Service Pueblo CO
246 PM MDT Wed Aug 19 2020 .SHORT TERM...(This evening through Thursday) Issued at 242 PM MDT Wed Aug 19 2020 The upper level high will be centered over northern AZ tonight and central AZ on Thu. This evening, a disturbance will move thru the flow aloft over eastern CO and could enhance the thunderstorm chances. The HRRR shows the potential for a line of storms coming off the eastern mtns early this evening and across El Paso and Pueblo Counties, with the possibility of some stronger cells in these areas. The line is then forecast to work its way east across the plains through the rest of the evening and maybe into the late night hours, although the HRRR generally shows weaker storms over the far southeast plains. The 18Z run of the NAM Nest shows a similar trend, but after 04Z shows some stronger isolated cells over the far southeast plains through about 06-07Z. Over western areas the models just show some weaker isolated to scattered showers/storms. SPC continue to show a marginal risk of severe storms over the I-25 corridor and southeast plains, with the main risk being strong wind gusts. However, cannot rule out a storm or two producing hail one inch in diameter. Thursday looks similar to today, with another disturbance moving over eastern areas and enhancing the chances for storms. The forecast models show limited shower/storm activity, but still some isolated to scattered storms should develop. Over eastern areas, it looks like storms will form over the mtns in the early to mid afternoon, with the potential for a line of storms moving across the I-25 corridor in the late afternoon and/or early evening and then progressing across the eastern plains through the evening. The eastern mtns and plains are again under a marginal risk for severe storms for Thu, with severe wind gusts being the main risk. However a couple stronger cells could produce hail around one inch in diameter. If stronger storms move over the Decker, Hayden Pass, Junkins, or Spring burn scars, there could be a flash flood risk this evening and again Thu afternoon/evening. .LONG TERM...(Thursday night through Wednesday) Issued at 242 PM MDT Wed Aug 19 2020 Thursday night the remains of existing showers and thunderstorms should drift southeast and quickly move out of our area. Although insolation and instability should be somewhat weakened by that point in the evening, storms encountering more favorable conditions could still potentially produce wind gusts over 50 mph and some hail. More isolated thunderstorms are expected in the afternoon Friday through Monday, with moisture and northwest flow aloft mainly driven by the upper-level high to the west. Light easterly upslope flow will continue to supply the low-mid levels with moisture through the Friday night , although most of the convective activity will remain over the higher terrain. Given the weaker steering flow at higher levels, a few storms could potentially move over I-25 by the time evening comes around, but the storms should quickly move south and out of our area. A few strong to severe storms are still possible, and more organized storms could produce winds near 60 mph and hail up to an inch in diameter. Monitoring for flash flooding over burn scars will be the primary concern. The weekend should be slightly drier as flow turns more westerly aloft, but some chances of convection still exist over the mountains in the afternoon-evening hours. While storm motions should be relatively slow, a main concern will be monitoring for new fires started by lightning strikes in areas with no precipitation, especially with less moisture at lower levels. Monday through Wednesday will see a transition in the synoptic pattern as an upper level trough sets in from the northwest by midweek, displacing that persistent high pressure and bringing some southwesterly flow into the region. A cold front will likely drop south across the plains by the end of the day on Wednesday, bringing some more moisture and increased chances for convective activity across our area during late afternoon. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 242 PM MDT Wed Aug 19 2020 Thunderstorms will be possible at KCOS, KPUB and KALS this evening. The main storm risks will be strong outflow wind gusts and possibly brief heavy rain which could temporarily lower ceilings and visibility. It looks like chances for storms at the terminal forecast sites will decrease or end by about 02Z. Storms will again be possible at the three sites Thu afternoon and evening. Otherwise VFR conditions are expected. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...GARBEROGLIO AVIATION...28
National Weather Service Raleigh NC
945 PM EDT Wed Aug 19 2020 .SYNOPSIS... A pair of fronts will weaken over the Southeast and Carolinas through Thursday, while high pressure otherwise builds across the middle Atlantic. && .NEAR TERM /THROUGH TONIGHT/... As of 945 PM Wednesday... 00Z surface analysis and radar trends indicated a the primary trough/front has been aided south into the southern Piedmont and coastal plain by fairly vigorous but non-severe convection this evening. scattered showers also continue to develop along outflow over the NE Piedmont. Aloft, the positive trough continues to sink into the lower MISS Valley, with a few disturbances in the SWrly flow over the SE states evident in water vapor. The most notable disturbance is off the N FL coast, and the RAP suggests this will lift along the Carolina coast late tonight and early Thursday. The 00Z GSO and MHX raobs were still fairly uncapped. Given the presence of the frontal zone/outflows and some ripples in the SW flow aloft, will maintain some slight chance to chance POPs for most of the night, with radar trends suggest the ongoing NE Piedmont convection likely to shift west toward the NW Piedmont. patchy fog and stratus are possible by sunrise, most likely from the Triangle to the NE behind the early outflows. Lows 67-71 && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 345 PM Wednesday... Downstream of the record-breaking sub-tropical ridge over the Southwest, a mid-upr level low will develop and become generally stationary over the lwr MS Valley through Thu night. Light swly flow will result downstream across cntl NC, between that trough/low and another subtropical ridge expanding from the sw Atlantic to the Carolinas. Weakly rising heights and light swly flow will result through the mid levels over cntl NC. At the surface, a trough/front is forecast to extend from the cntl and srn NC coast wswwd to a weak low over cntl NC, while high pressure ridges across the middle Atlantic. Prevailing ely flow and associated cooler than average temperatures in the lwr-mid 80s will result over cntl NC, with a related good chance of overnight stratus. Lows again 65 to 72. Although the column overall will moisten in the aforementioned swly flow aloft, to around 1.7-2.0", the wwd expansion of the subtropical ridge will likely limit convective coverage to generally scattered, to locally numerous. The increasing deep layer moisture and only weak flow aloft will limit downdraft intensity and risk of severe wind gusts. Instead, localized, mainly urban and poor drainage flooding will be possible from slow-moving convection. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 355 PM Wednesday... Very little change to the overall weather pattern through the extended forecast period. Central NC will remain on the NW periphery of the Bermuda High, with a trough sitting over the MS/TN Valley. The high over the Desert Southwest will remain in place through Wednesday. The trough to the west will weaken with time this weekend before shifting eastward through the mid-Atlantic early next week. The southerly return flow around the high/ahead of the trough will continue to advect warm air in to the region. Temperatures will moderate back to normal by the weekend, with highs in the upper 80s to low 90s and lows in the upper 60s to mid 70s. The RH percentages should decrease into the 60s over the weekend, dropping into 50s across by early next week. Best chances for diurnal convection will be across the south and west Friday and Saturday, with decreasing chances and coverage expected thereafter. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 745 PM Wednesday... Scattered SHRA/TSRA will continue through this evening over portions of the Sandhills, NE Piedmont and northern Coastal Plain. Reduced vIS to 1 SM or less, gusty and erratic winds to 30 mph, lightning and strong up/down drafts are expected near storms. Stratus and fog will develop late tonight through early Thu creating areas of IFR/MVFR ceilings and VIS, with the relative highest probability of occurrence at RDU, FAY, and RWI. Scattered SHRA/TSRA will develop again Thu afternoon-evening. Outlook: Late night early morning stratus and fog is possible through early next week, and the coverage of storms will gradually decrease by this weekend. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...bls SHORT TERM...MWS LONG TERM...KC AVIATION...JJT
Area Forecast Discussion
National Weather Service Reno NV
223 PM PDT Wed Aug 19 2020 .SYNOPSIS... Smoke and wind are the main impacts the next couple days with a few thunderstorms across Mono and Mineral Counites this evening. Some cooling overnight will provide relief from the heat for the end of the week. After a couple dry days, thunderstorms may return to the eastern Sierra and western Nevada by Sunday. && .SHORT TERM... Temperatures will cool the next couple days as low pressure off the Pacific northwest coast pushes the ridge east for a couple days. Unfortunately the low is going to maintain a west to southwest flow the next couple days, driving smoke from the northern CA wildfires into the Sierra and western NV. While wildfire smoke dispersion is a challenge to predict, as long as there are large active wildfires across northern CA, we are going to be vulnerable to smoke and unhealthy air quality for the foreseeable future. Current smoke plume over the Sierra and western NV should shift east, bringing some relief this evening but additional smoke will move into the Sierra and western NV around 10 pm. If you are trying to cool your home tonight, remember to close the windows before heading off to bed. HRRR Smoke is predicting dense smoke and poor air quality by early Thursday AM. Showers and thunderstorms have built over Mono and Mineral Counties early this afternoon. Expect some gusty outflow winds over 50 mph, brief heavy rain and hail through 9 PM. Brong .LONG TERM......Saturday through Wednesday... Some changes were made to increase t-storm chances for Sunday PM through Monday, including possible showers for Sunday night. Overall, above average temperatures are likely to continue, but not quite as hot as our recent heat advisory event. For this weekend, Saturday still looks dry with typical afternoon zephyr breezes, as high pressure remains centered over the southwest US. This ridge isn`t quite as intense as this week (500 mb heights around 594 DM after peaking over 600 DM) so while we continue to stay on the warm side (highs mid-upper 90s for lower elevations, mid- upper 80s near the Sierra), record highs and heat-related headlines are unlikely. Sunday through Monday look more like a return to thunderstorm activity, as another trough approaches the Pacific Northwest. Meanwhile, a push of moisture from the southwest US could combine with remnant tropical moisture from Hurricane Genevieve. The time frame may fluctuate depending on the track of the hurricane, but overall the best chances for thunder appear to remain south of US-50 Sunday afternoon. The moist air mass with warmer overnight temperatures may be capable of keeping some shower activity going through Sunday night/Monday morning. Then for Monday afternoon as instability increases, the chances of thunder look more favorable, with storms possibly advancing farther north. Tuesday is a little more of a wild card for thunder chances, as some model guidance showed one final shortwave passage which could kick up a few afternoon storms, while others dry things out. For now, we will keep a low end possibility of thunder south of US-50, but may need to add some thunder chances for northeast CA, northwest or west central NV if more of the ensemble data trends toward the higher instability scenario. There is somewhat better agreement for Wednesday being dry so we will not include any thunder chances. For both days, temperatures look to ease down a bit to the lower-mid 90s in lower elevations/80s near the Sierra with modest afternoon zephyr breezes. MJD && .AVIATION... Reduced visibility due to wildfire smoke will impact much of the Sierra and western NV through at least Thursday. Visibility may drop below 1 mile at times. Winds will remain gusty this evening with mountain wave turbulence east of the Sierra Crest. Winds may be a bit slow to diminish tonight and should turn gusty once again in valleys by late Thursday morning. Brong && .FIRE WEATHER... Gusty west to southwest winds on track for critical fire weather conditions through at least 9 PM this evening. Jet stream will pass over the Sierra tonight, which may allow winds to stay gusty on mid and upper slopes past 9 PM. Newest addition to the forecast is another period of red flag conditions with gusty afternoon and evening winds along the Sierra Front Thursday afternoon and evening. Winds will also be gusty across eastern Lassen and northern Washoe, but appears wind speeds will remain just below red flag conditions. Humidity is looking rather low the next couple days with very minimal overnight recovery, which is typical for mid-August. Brong && .REV Watches/Warnings/Advisories... NV...Red Flag Warning until 9 PM PDT this evening NVZ420-423-458. Red Flag Warning from 2 PM to 9 PM PDT Thursday NVZ420-421. Lake Wind Advisory until 9 PM PDT this evening for Washoe Lake in NVZ003. Heat Advisory until 11 PM PDT this evening NVZ001-003>005. Dense Smoke Advisory until 11 AM PDT Thursday NVZ002-003. Lake Wind Advisory until 9 PM PDT this evening NVZ004. CA...Red Flag Warning until 9 PM PDT this evening CAZ270-271-278. Dense Smoke Advisory until 11 AM PDT Thursday CAZ071-072. Lake Wind Advisory until 9 PM PDT this evening CAZ071. && $$ For more information from the National Weather Service visit...