Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/10/21

Area Forecast Discussion
National Weather Service Amarillo TX
639 PM CDT Sun May 9 2021 .AVIATION...00Z TAFs... Primary aviation concern is the likelihood of lower end MVFR to IFR stratus spreading southeast tonight into tomorrow as upslope southeasterly winds continue. At this time, expect AMA to stay out of IFR while DHT and GUY, closer to where stratus will initially generate, look to dip below 1000 feet for at least a couple hours. Secondary concern is the potential for precipitation. Shower and thunderstorm coverage to our west has been underwhelming, with all thunder now likely to miss both DHT and AMA. Additionally, weak coverage reduces confidence that any showers will directly impact the terminals as well. Have thus stuck with only VCSH mentions with this update. Otherwise, expect southeasterly winds to continue through the period. Ferguson && .PREV DISCUSSION... /Issued 222 PM CDT Sun May 9 2021/ SHORT TERM...Tonight through Tomorrow Night... Latest upper level analysis reveals elongated area of low pressure with main cyclonic flow over portions of MT into the western Dakotas. The broader cyclonic flow engulfs most of the western and central CONUS. A minor perturbation in the west southwest flow aloft is moving across north central NM at this time, helping to kick off convection around the Sangre De Cristo Mountains. A post-frontal upslope flow is also contributing to the convective initiation along the higher terrain of NM and southeast CO. This convection will gradually move easterly with a mean steering flow of 20 to 30 knots, and most CAM output suggest storms will be crossing into TX around 00z, perhaps a bit earlier in the western OK Panhandle. Looking at potential for severe storms this evening, the overall probability is low mainly due to limited instability (MUCAPE less than 500 J/kg in western zones). However, areas adjacent the higher terrain of NM have slightly better parameters that could support some brief rotating updrafts (better effective shear, steep lapse rates, MLCAPE around 500 J/kg, more terrain influence). As storms move into our area, they will run into weaker mid level lapse rates and MLCAPE values of around 200 J/kg resulting in lower cloud-layer shear. That being said, forecast soundings do indicate 700 to 1000 J/kg DCAPE and steep low level lapse rates along the far western zones as storms move in. Given this, storms may actually tend to collapse and produce some strong wind gusts as they move into the western zones. One thing to note: the HRRR still attempts to produce some UD Helicity (now southwest of Amarillo with 17z run), but the HRRR is notorious for over-doing convection in post-frontal upslope flow. This is likely the case here seeing as the same model is only producing ~100 J/kg MUCAPE in pre-storm environment. That being said, the upslope flow combined with a minor perturbation aloft should help carry storms into the Amarillo area around 9 PM or so, but they should become sub-severe by that point. Lingering showers and a few storms are expected to move out of the area or dissipate with loss of upper lift between 06z and 09z. Low clouds will fill in across the area after 06z, and may stick around through most of the day on Monday (very light sprinkles or even some light drizzle can`t be ruled out Monday, but should not amount to measurable precip). High temperatures on Monday will be a good 15 to 20 degrees below normal. Another minor lead perturbation will enhance shower and possibly elevated thunderstorm potential Monday night as low level theta-E increases from south to north. The best chances will be across the northern zones closer to the best 500mb PVA - yet the best instability will be in the south. Severe is not expected at this time, but if the RAP is right elevated instability and effective shear may be sufficient for some strong storms in the southeast TX Panhandle, should any storm form there. Ward LONG TERM...Tuesday through Saturday... Tuesday an upper level trough will continue swinging through the northern Rocky Mountains into the Upper Great Plains by Wednesday. Post-frontal air will continue to be present Tuesday and Wednesday with daytime highs well below normal in the 50s to low 60s. Also, during this time period there will be a chance for showers with isolated thunderstorms. Expecting cloudy and dreary conditions through these two days as well with surface winds out of NE, E, and SE. These winds will bring in low level moisture with upslope flow helping to shroud the area in low clouds until Thursday. On Thursday, upper level ridging will build in over the Desert Southwest and surface winds will shift to the S to SW allowing for the low clouds to clear out and temperatures to warm into the 70s again. On Friday a leeside low will develop over northern NM and southern CO increasing the pressure gradient. Southwest winds will become breezy on Friday afternoon with speeds around 20 mph with gust around 30 to 35 mph. Downsloping winds and clear skies under upper level high pressure will allow temperatures to return into the 80s once again. Isolated showers and thunderstorms may be possible, late in the afternoon on Friday. Models do depict some good theta-e advection at H7 moving in from the south into NM and wrapping back to the east into the Panhandles. The NBM is only giving PoPs in the east for now but the GFS is hinting at precip starting in the far western Panhandles. Have increased PoPs to cover more of the FA due to the strong signals in the GFS and even the new EC hinting at precip now. Going into Saturday, highs return to the 80s in the afternoon with the upper level ridge building over the area. Hoffeditz && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 77/89
Area Forecast Discussion
National Weather Service Columbia SC
1017 PM EDT Sun May 9 2021 .SYNOPSIS... Low pressure over the Ohio Valley with a trailing cold front through the lower Mississippi Valley will move east allowing strong southerly flow and increasing moisture overnight. The cold front will move into the region Monday and stall just south of the area resulting in rain chances through Thursday with below normal temperatures more likely by midweek. && .NEAR TERM /UNTIL 7 AM MONDAY MORNING/... Low pressure was over the Ohio Valley with a trailing cold front though the lower Mississippi Valley. This is resulting moisture advection with dewpoints rising into the low 60s overnight ahead of the approaching cold front. HRRR and RAP showed pwats increasing to around 1.5 inches with weak instability developing across our western counties. Isolated showers and thunderstorms developing across the northern portion of the CSRA and western Midlands as models advertised. Will probably see an increase in convection overnight as short wave crosses the area. Will increase pops to low chance across the western and northern counties to account for scattered convection. Overnight min temps in the low to mid 60s with considerable clouds and warm advection. && .SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Monday and Monday night...Short wave moving east of the region in the morning. Surface front appears to move into the Upstate region. There may be a few scattered showers in the morning then a break through early afternoon as lift weak. The air mass will become moderately unstable in the afternoon with CAPE possibly above 1000 J/kg...possibly focused in the Piedmont into the northern Midlands closer to frontal boundary. The CAMS are suggesting strong thunderstorms may develop near the front late in the afternoon or evening and focus toward the Pee Dee in region of convergence as the front back-doors through the area. The deep layer shear is a little stronger closer to the NC border and upper level divergence associated with 250mb jet across the Carolina Mountains may result in enhanced lift north of CAE. Can`t rule out a shower or thunderstorms anywhere but the northern Midlands to the Pee Dee may be the focus. Back door fronts need to be watched for strong convection. Continued scattered convection coverage in the afternoon and evening then diminishing overnight. Temperatures near normal for this time of year in the low to mid 80s. Cold air advection overnight as the frontal boundary back- doors through the region. Tuesday and Tuesday night...The front initially sets up to the south of the area or near the CSRA. Precipitable water highest in the CSRA into the Low Country. Moisture flux and weak insentropic lift should result in scattered showers/perhaps a thunderstorms across the southern Midlands and CSRA through the day. Went below the blended guidance due to cold advection with high temps mainly in the low to mid 70s. Cold air damming wedge development appears to be an increasing possibility Tuesday night with favorable upper level convergent flow across the Mid Atlantic region and weak trough at 850mb in the lower Mississippi Valley/Gulf coast region. Weak trough/low along the coast. Surface ridge east of the Appalachian Mountains appears to be strengthening overnight. Deterministic GFS and ECMWF have been consistent last couple of runs with this trend. So increased pops Tuesday night as moisture flux and isentropic lift increases. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... NAEFS has 1030+ mb surface ridge centered over the northern Plains/Great Lakes region which is at the 99th percentile for this time of year. So a very strong ridge/not in an ideal position for cold air damming but strong enough to result in in- situ wedge. There is now support from ensembles. So expect moisture flux and isentropic lift to increase during Wednesday morning. Will keep higher pops across the south Wednesday but threat for rain may be increasing. Slowly decaying wedge Thursday with light rain or drizzle possible through day. Temperatures will be tricky both days...for now went below the NBM guidance below the 25th percentile...which may still be too high for max temps. At most temperatures in the upper 50s to low 60s but possibly much cooler. Drying out Friday with upper trough along the eastern seaboard and northwest flow aloft. This pattern continues into the weekend with cooler than normal temperatures but fair weather with strong pressure ridge over the eastern CONUS. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... A tight pressure gradient over the region should keep winds up around 6 to 8 knots through most of the night and into the early morning. This will prevent any fog concerns. However a low level jet will strengthen and move over the area in the next several hours then shift east around 09Z. If surface wind speeds decrease a little more than expected, then there will be potential to meet LLWS criteria. The most likely timing for LLWS would be from 05Z to 09Z. A shortwave will move over the area on Monday morning and may support showers. However the consensus from the hi-res models suggests that any coverage would be isolated. The better chance for rain and associated restrictions will be in the afternoon and evening. Daytime heating should allow showers and thunderstorms to develop after 17Z. Have included VCSH in the TAFs at the moment due to lower confidence in the later portion of the TAF period. A backdoor cold front will move into the forecast area on Monday evening which will prolong the chance for showers and thunderstorms. Low ceilings may also develop behind the front later in the night. EXTENDED AVIATION OUTLOOK...Ceiling and visibility restrictions possible Tuesday and Wednesday with a cold front stalled over the region. This will also keep showers in the forecast through mid-week. Conditions may improve late this week as dry, high pressure moves into the region. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Charleston SC
1016 PM EDT Sun May 9 2021 .SYNOPSIS... High pressure will prevail through early week. A cold front will drop south through the region Tuesday and linger through the end of the week as high pressure remains to the north. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Late this evening: Cirrus has quickly expanded overhead this evening so some minor tweaks were made to sky cover for the next few hours. Otherwise, no significant changes. Previous discussion continues below. Early this evening: A comfortable spring evening is on tap with warm temperatures and a persistent southerly breeze. Cloud cover will increase steadily from the northwest through the night. We should be rain-free, but will have to watch the progression of upstream convection along a cold front moving across Tennessee, Mississippi, and Alabama. The convection will certainly either be diminished or on a diminishing trend as it approaches, but the HRRR seems to be picking up on showers develop across interior southeast Georgia along an outflow boundary. For now the forecast is dry but we will watch upstream radar trends and subsequent runs of the HRRR. Lows are forecast to range in the mid to upper 60s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Monday: The zonal flow across the Southeast U.S. will buckle ahead of southern stream shortwave that will cross the Deep South and offshore of the Southeast U.S. Monday. The shortwave will support an area of showers/tstms to the west which will likely be in a steadily weakening state as it approaches mid- late morning as the corridor of strongest forcing outpaces the convection. Omega cross sections show a large area of subsidence filling in behind the shortwave as it pushes off the coast by early afternoon. This is well reflected in model soundings which depict a strengthening capping inversion. There are signals that renewed convection will fire across central Georgia by early afternoon which is forecast to move into the local area by peak heating. Adjusted model soundings at KRVJ, KTBR and KAQX suggest the cap either weakens or completely mixes out in the Reidsville-Allendale corridor, so convection may very well survive in this area before weakening as it moves east and encounters an increasing subsident/more stable environment at the coast. Pops were nudged up slightly into the 40% range across the west per timing from the simulated reflectivity output from the latest H3R with 20- 30% pops maintained across the coastal counties. Highs will warm into the lower-mid 80s with a few upper 80s possible from Ludowici to Darien. The sea breeze looks to remain pinned until late given the westerly flow in the wake of the shortwave. It will eventually move inland bringing gusty conditions to mainly the coastal counties. Tuesday: A backdoor cold front will drop south into the area as high pressure tries to bridge the southern/central Appalachians. Guidance has been wavering on the exact timing of the front, but consensus favors the wind shift moving across southern South Carolina during the late morning/early afternoon then approaching the I-16 corridor by peak heating. The southward moving frontal surface coupled with an increasing unstable environment and passing impulses aloft should support scattered showers/tstms with the greatest coverage occurring along/south of I-16. Marginally strong 0-6km bulk shear along with some elevated DCAPE could support a few strong to marginally severe tstms during the mid-afternoon to early evening period across mainly Southeast Georgia, including the Savannah Metro Area. An organized severe event looks unlikely at this time. 30-50% pops will be highlighted into the evening hours, highest Southeast Georgia. Highs will be a bit tricky as some compressional heating could help boost temperatures prior to FROPA. Highs will range from the mid-upper 70s across the north with lower-mid 80s elsewhere. Tuesday Night and Wednesday: The 09/12z GFS is similar to its 00z run in finally come in line in depicting a much flatter trough moving across the Ohio Valley and Great Lakes on Tuesday which subsequently results in weaker cyclogenesis off the Georgia and northeastern Florida coast. This is now more in line with other guidance such as the last several runs of the ECMWF. The backdoor front should be south of the Altamaha River near sunset with the entire forecast area expected to remain in the cold sector of the strengthening wedge through Wednesday. Lows will range from the mid-upper 50s north and interior to the lower-mid 60s elsewhere. A favorable overrunning pattern is forecast to develop atop the wedge overnight as the weak surface low begins to form. This should result in a gradual uptick in showers late Tuesday night which will linger into Wednesday. Diabatic cooling induced by moderate rain falling into the wedge will help keep temperatures with highs only expected to peak in the lower-mid 60s for areas adjacent to the CSRA and Southern Midlands and across portions of the Charleston Tri-County area. Elsewhere, highs will range from the upper 60s to as high as the mid 70s across portions of McIntosh County where influences from the wedge will be less. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Wednesday Night and Thursday: The risk for wet weather will persist as a modest overrunning pattern within a plume of PWATs 1.50-1.75" holds in place atop a weak surface wedge. Subtle cyclogenesis will likely be ongoing off the Georgia and northeastern Florida coast Wednesday evening and the cyclone will slowly become better defined into Thursday as it becomes more aligned with the right entrance region of the subtropical jet and feels the influence of shortwave energy moving across the Ohio Valley. The surface low is forecast to meander farther offshore Thursday night. There is potential for locally rainfall during this period with a pronounced 850 hPa front forecast to become aligned right over the region juxtaposed with deep- layered omega. However, with meaningful instability will likely be lacking both at the surface and aloft, so overly intense rainfall rates are not expected. The exact evolution of how Wednesday night into Thursday remains in flux as the details are highly uncertain this far out. Generally favored a blend of the NBM with the wetter SuperBlend to generate pops around 50% area wide. Lows will range from the lower 50s well inland to the lower 60s at the beaches. Highs will range from the mid-upper 60s well inland to the upper 60s/near 70 at the coast. Friday: High pressure will build farther to the south on Friday as mid-level heights begin to rise. Similar to yesterday, the operational GFS looks a bit too dry this far out with at least a third of the GEFS members remaining aligned with the NBM and ECMWF to keep some degree of measurable rainfall in place. The best window for measurable rainfall looks to be in the morning before drier air finally works south and deepens through the entire forecast area. Slight chance pops were maintained. Highs will generally top out in the mid 70s away from the beaches with lows Friday night ranging from the lower 50s inland to the lower-mid 60s at the beaches. Saturday and Sunday: Dry, high pressure will prevail as a pronounced upper ridge builds across the Southeast U.S. and Deep South. Highs will top out around 80 each day with lows ranging from the mid 50s inland with lower-mid 60s at the coast. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... VFR conditions are expected to prevail through 00z Tuesday. Breezy conditions will last for a few more hours before the gusts diminish. We will see another round of gusty winds start late late Monday morning and peak in the afternoon with gusts into the 20-25 knot range again. Perhaps the biggest forecast question has to do with the potential for showers and thunderstorms Monday afternoon. The forecast calls for showers and thunderstorms to develop to the west and push in through the afternoon. Perhaps the best chance for direct impacts (at this time) is at KSAV. Confidence still isn`t particularly high, so we have simply introduced a VCSH at 19z. Extended Aviation Outlook: Flight restrictions likely in showers and thunderstorms Tuesday through Thursday. && .MARINE... Tonight: High pressure will be centered far off the coast. Meanwhile, a cold front will be approaching from the west. The interaction between these two synoptic features and a low level jet will cause the pressure gradient to elevate with time, causing winds to increase this evening and overnight. Small Craft Advisories are in effect for all of the waters, including the Charleston Harbor. The models indicate that these strong/gusty winds might start a few hours later than forecasted and we trended that way with the forecast. However, with the advisories already out, we didn`t feel that changing the start times by about three hours would add much value. Expect gusts to 25-30 kt, peaking around midnight. The strong/gusty winds will start to ease before daybreak Monday. Seas will peak around 5-6 ft beyond 10 nm. Models have them slower to subside overnight, so for that reason we extended the ending of the advisories until daybreak for most of the waters. Monday: Southwest winds will gradually relax Monday as the pressure gradient loosens a bit ahead of a backdoor cold front. The sea breeze could still get a bit gusty along the land/sea interface including Charleston Harbor, but it may not be quite as gusty as Sunday. Future updates will have to watch for a possible need for a low-end Small Craft Advisory in the Charleston Harbor. Otherwise, southwest winds will remain around 15 kt, possibly a tad higher along the Charleston County coastal waters. Seas will average 2-4 ft. Tuesday: A backdoor front will gradually work south through the day. Winds will become northeast post FROPA, reaching the Georgia waters during the evening hours. Fairly light winds will occur ahead of the front, then increase to northeast 15 kt as the front drops south. Seas will average 1-3 ft. Wednesday through Friday: Northeast winds will prevail through the period as an inland wedge takes shape Wednesday and weak low pressure develops and moves offshore. The strongest winds will occur Wednesday with speeds in the 20-25 kt range with gusts approaching 30 kt. Small Craft Advisories are likely Wednesday with conditions slowly improving Thursday into Friday as the gradient relaxes and high pressure builds farther to the south. Sea will reach as high as 4-6 ft nearshore waters and 5-7 ft offshore waters Wednesday night into Thursday before subsiding. Rip Currents: The combination of astronomical influences and gusty winds along the sea breeze will support a moderate risk for rip currents for the South Carolina beaches Monday. A high- end low risk will be in place for the Georgia beaches per slightly weaker winds expected there. An elevated rip current risk will redevelop Wednesday and continue into Thursday with breezy northeast winds developing. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 3 AM EDT Monday for AMZ330. Small Craft Advisory until 6 AM EDT Monday for AMZ350-352-354- 374. && $$ NEAR TERM...BSH SHORT TERM... LONG TERM... AVIATION...BSH MARINE...
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1025 PM CDT Sun May 9 2021 .UPDATE... And 25 minutes later the storm across Gillespie county decided to weaken rather than tap into the 2000-3000 j/KG of CAPE that the HRRR soundings and SPC mesoanalysis still showed. Based on that we have let the last 5 remaining counties go in the Severe Thunderstorm Watch. While an isolated shower or non-severe storm can`t be ruled out early Monday morning as the front sags south chances are very low. More severe weather and possibly heavy rain for Monday and Tuesday though! && .PREV DISCUSSION... /ISSUED 957 PM CDT Sun May 9 2021/ UPDATE... Have dropped the Severe Thunderstorm Watch for the Austin Metro area and Williamson County. Have retained it for some of the Hill Country counties due to a pesky storm that likely formed when the outflow of the earlier supercells interacted with the front. While the storm has generally been struggling, there is still plenty of CAPE present for the storm to tap into, so out of abundance of caution have extended the watch for another 2 hours for Kerr, Kendall, Gillespie, Blanco, and Llano Counties. PREV DISCUSSION... /ISSUED 807 PM CDT Sun May 9 2021/ UPDATE... Made some adjustments to the PoPs for the evening based on the current radar trends. A single supercell is moving through Gillespie and Blanco County. The storm has been moving to the southeast fairly steadily which would take it into Southern Blanco, Northern Kendall, and eventually Comal Counties. Think the storm should generally weaken with the loss of daytime heating, but have raised PoPs downstream of the storm to account for it. Have also lowered PoPs across the northern Hill Country. Took the moment to retrend the hourly grids as well. PREV DISCUSSION... /ISSUED 628 PM CDT Sun May 9 2021/ AVIATION... In terms of precipitation at AUS we will have to monitor the supercell moving into Llano County. It it was going to impact AUS it would be around 02z, but models are showing it generally weakening as it moves east towards I-35. Ceilings in general will drop at all sites tonight once more with plenty of surface moisture in place. MVFR cigs will build in across the I-35 corridor around 05z with IFR likely by 07z. While northerly and northeasterly winds are likely to be breezy as a cold front sags through the area preventing fog it will do little to help with ceilings which will linger into Monday morning. IFR should stick around through much of the morning hours across the I-35 terminals, with ceilings rising to MVFR by early afternoon. At DRT MVFR cigs will be possible by 10z and will stick around through about 19z on Monday. Generally easterly winds around 10 knots will be possible at DRT. Scattered showers and thunderstorms will be possible late in the period across the Rio Grande tomorrow evening, but will not include those in this TAF package. PREV DISCUSSION... /ISSUED 314 PM CDT Sun May 9 2021/ UPDATE... A Severe Thunderstorm Watch is in effect until 10pm for Blanco, Burnet, Comal, Gillespie, Hays, Kendall, Kerr, Llano, Travis, and Williamson Counties. The primary hazards are large hail and damaging wind gusts, with several very large hail reports of 2" or greater possible. -Morris PREV DISCUSSION... /ISSUED 214 PM CDT Sun May 9 2021/ SHORT TERM (Today through Monday)... A busy surface pattern is in place across portions of western and central Texas this afternoon. As of 18Z, a dryline is noted from near Sonora to near Del Rio with a cold front located from Brownwood to just north of San Angelo into the central Permian Basin of west Texas. Across most of south central Texas, a warm and moist air mass is in place with current temperatures in the lower 80s to mid 90s and dewpoints in the lower 60s to lower 70s. The above mentioned cold front will continue to sag southward through late this afternoon and early this evening. We are already seeing some convection go up along the cold front across north Texas and based on the latest hi-res model data, we should see additional convection develop along the front over the far northern Hill Country in the vicinity of Mills/San Saba/Lampasas counties where SPC mesoanalysis places the highest CAPE values with little to no CIN. Given plenty of deep layer shear and healthy mid-level lapse rates, severe thunderstorm development appears likely. The latest SPC outlook continues to highlight areas generally along and north of a Comfort to Kyle to Giddings line in a Slight Risk (Level 2 out of 5). This does include the Austin Metro area. Just south of this line, including the cities of Kerrville, Boerne, San Marcos and La Grange, the threat drops slightly into the Marginal (Level 1 out of 5). Regardless of the threat level, strong to severe thunderstorms are forecast to develop late this afternoon through early this evening. The main severe weather concerns will be large hail and damaging winds. Severe parameters favor some very large hail (>2" diameter) for areas outlined in the Slight Risk category. With the loss of daytime heating, we expect a decrease in the severe weather threat along with an overall decrease in the coverage of convection as we head into the very late evening hours. We will maintain a low chance (20%) for some showers and thunderstorms after midnight across the Hill Country and I-35 corridor north of San Antonio. Overnight lows will be cooler behind the boundary in the Hill Country with some lower to mid 60s, while it remains warm elsewhere with lows generally in the mid 60s to mid 70s. On Monday, another active weather day is shaping up during the late afternoon and evening hours, especially for areas along and west of a Llano to San Antonio to Dilley line. With a cold front in the area and an approaching mid-level disturbance, we should see a round of convection develop over the southern Edwards Plateau, western Hill Country and portions of the Rio Grande plains. Large hail and damaging thunderstorm winds will be the main severe weather concerns. High temperatures will vary greatly depending on the location of the front. For now, we will keep highs down into the lower 70s across portions of Llano and Burnet counties. To the south of the front, warm temperatures are in store with mid 80s to near 100 degrees expected. While the overall severe weather threat should gradually ease as we head into early Monday morning, we will then need to focus our attention on some pockets of heavy rainfall over the southern Edwards Plateau and Hill country. Overnight lows will again be tough to pinpoint with a front in the area. For now, we will forecast lows as cool as the upper 50s in the Hill Country with lower 70s for areas south of Highway 90. LONG TERM (Monday Night through Saturday)... Tuesday morning the surface cold front is likely to be draped near our southern border and should continue sagging slowly southward. However, flow at 850mb and 700mb will remain generally out of the south, with rich moisture continuing to flow in aloft over the front. Model PW values of 1.5-2.1" are forecast across all but far northwestern portions of Val Verde and Edwards counties Tuesday into Tuesday evening. Areas of showers and thunderstorms are likely through the day thanks to the widespread isentropic ascent and a potential mid- level perturbation as well. We are currently under a broad-brushed marginal risk of severe thunderstorms in the SPC Day 3 Outlook, with large hail likely to be the primary threat from the elevated thunderstorm activity. SREF mean MUCAPE hovers in the 1500-2500 J/kg range through the day, night and into Wednesday, likely highest near the Rio Grande where steeper mid-level lapse rates are anticipated in the EML. Even the outlier NAM depicts ample elevated instability across much of the area. Given the high moisture content, locally heavy rainfall could also be in the cards, and we are under a marginal risk in the WPC Day 3 Excessive Rainfall Outlook for Tuesday to cover this risk. Nailing down the timing and location of highest risk is impossible at this moment. Suffice it to say the entire region should be on the lookout for the potential for both large hail and localized flooding concerns Tuesday and Tuesday night with more clarity hopefully to come after the first couple rounds of storms which will have a large impact on the environment. I would anticipate a marginal risk of severe storms, again with hail as the primary risk, may be needed for Wednesday too as overrunning flow over the shallow cold layer will keep shower/storm chances in the forecast through the day. Pwats should fall below 1.5" across our northern counties during the day as the 850-700mb trough finally pushes to the east and flow swings around to the north at mid-levels Any heavy rainfall threat will hopefully remain south of the metros by midday. The focus for storms should shift southwest to the Winter Garden region by Wednesday night and at this time it looks like we`ll finally dry out for Thursday and Friday. In terms of temperatures, there`s still quite a bit of spread in the models for Tuesday and beyond and the picture isn`t much clearer than it was this time yesterday. The NAM remains a cold outlier, but even in the GEFS the membership varies from highs in the upper 50s to highs in the mid 80s on Wednesday at AUS. The SREF is much more clustered around a somewhat warmer solution with only a couple of cold outliers. This is likely lending some credence to the NAM being out to lunch on this particular airmass, but it`s puzzling to see such a stark difference between it and the SREF mean! Regardless, cooler than normal conditions are rather likely in the Tue-Fri time frame, coldest on Wednesday with a little bit of a warm up (and a return of high dew points) possible through the weekend as mean sfc ridging dominates the eastern CONUS. Could see rain chances return on Saturday. AVIATION... Cigs along the I-35 corridor have lifted back to VFR and will generally remain VFR through this afternoon and early evening. The exception will be near AUS where some convection is expected to impact the terminal during the 23-03Z time frame. For now, we have included a TEMPO group between 00-02Z, but this may need to be altered depending on storm development to our north. Otherwise, look for low clouds to develop and expand over the region late evening and overnight with MVFR cigs in store for SAT and SSF. We did include a period of IFR cigs at AUS as some slightly cooler air in the boundary layer could promote lower cigs and some fog. MVFR cigs should also make it to DRT and we will begin MVFR conditions at 10Z. All sites should see some gradual improvement tomorrow, but AUS likely to remain MVFR well into the afternoon hours. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 87 69 79 63 75 / 20 40 30 60 80 Austin Bergstrom Intl Airport 88 69 80 63 76 / 20 40 30 50 80 New Braunfels Muni Airport 88 71 84 65 79 / 10 50 30 50 70 Burnet Muni Airport 87 65 73 59 73 / 30 30 30 60 80 Del Rio Intl Airport 102 72 93 69 82 / 0 - 30 60 50 Georgetown Muni Airport 88 67 75 61 74 / 40 40 30 60 80 Hondo Muni Airport 93 72 91 67 82 / - - 30 50 70 San Marcos Muni Airport 88 69 82 63 77 / 20 40 30 50 70 La Grange - Fayette Regional 89 73 86 67 79 / 20 30 20 40 70 San Antonio Intl Airport 90 72 86 66 80 / 10 40 30 50 70 Stinson Muni Airport 93 74 88 67 82 / 10 10 20 50 60 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Treadway Long-Term...05
Area Forecast Discussion
National Weather Service Grand Rapids MI
728 PM EDT Sun May 9 2021 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 PM EDT Sun May 9 2021 - Frost/Freeze conditions for 3 more nights starting tonight - Mainly dry weather is expected for the upcoming work week - A warming trend begins mid week && .DISCUSSION...(This evening through next Sunday) Issued at 330 PM EDT Sun May 9 2021 - Frost/Freeze conditions for 3 more nights starting tonight We have issued a Freeze Warning tonight for our northern two rows of counties and a Frost Advisory for the remainder of the CWA. We are expected readings to dip to near freezing and below in spots across Central Lower Michigan. Conditions are not ideal in terms of radiational cooling as there will be some stratocumulus around and winds will not be light in lower layers of the atmosphere. 10-20 knot winds are seen in BUFKIT overviews below 5,000ft. So, there is some hope that damage to early season fruit and vegetation will not be severe. The next two nights, Monday night and Tuesday night we will be in much the same set up. It looks like freezing temperatures may be a bit more widespread however. Winds are similar though, not calm by any means as the high is not directly over the area. We are certainly looking at two additional nights of headlines in regard to Frost/Freeze. - Mainly dry weather is expected for the upcoming work week The rain, what there was of it for our area, is in the process of clearing out of the south at this time. That said, all I-94 observation sites are no longer reporting rain. Much of the upcoming work week looks dry if not dry entirely. Ensemble data would support this idea with very little in the way of precipitable water in the column to work with. It does bother me a bit though that there are shortwaves in the area and in general an upper trough in place both Monday and Tuesday. Would not be shocked to see an isolated shower develop here or there either day, but ridging should keep things dry and that is what our going forecast is. Next decent chance for rain will likely come next weekend with a warm front lifting into the area. But, given dry southeast outflow out of an expansive area of high pressure would not be surprised if things trend drier. - A warming trend begins mid week 850mb temps remain below Zero C into mid week. Hence, our temperatures will remain below normal into Wednesday. It is roughly about the Wednesday time frame that 850mb temps trend positive with a slow creep of a moderating trend. Certainly not hot by any means as by the weekend we are around +5C. By the end of the week and into next weekend we should at least be back to near normal. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 728 PM EDT Sun May 9 2021 VFR conditions will continue through Monday morning. North winds will be AOB 10 knots tonight then gust to near 20 knots at times on Monday. && .MARINE... Issued at 330 PM EDT Sun May 9 2021 Winds are in the process of increasing this afternoon associated with a wind shift to the north. The north shift will increase fetch lengths to 100s of miles. There will be a push of winds down the lake with speeds of 20-30 knots late this afternoon and evening. HRRR seems to have the best handle on the development of these winds. Waves will correspondingly jump into the 3-6 foot range this evening. Highest waves will occur this evening down towards South Haven where wave heights may reach 6 feet or so. Overnight winds will shift a bit to the north-northeast tonight where the highest waves will be streaming off of Big Sable Point. To keep things simple we have a Small Craft Advisory in place for all zones through 800am on Monday. The remainder of the early portion of the work week, Monday and Tuesday will feature northerly winds of 10-20 knots which should keep waves below advisory criteria. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Frost Advisory from 1 AM to 9 AM EDT Monday for MIZ050>052- 056>059-064>067-071>074. Freeze Warning from 1 AM to 9 AM EDT Monday for MIZ037>040- 043>046. LM...Small Craft Advisory until 8 AM EDT Monday for LMZ844>849. && $$ SYNOPSIS...Duke DISCUSSION...Duke AVIATION...Ostuno MARINE...Duke
Area Forecast Discussion
National Weather Service Wichita KS
711 PM CDT Sun May 9 2021 .SHORT TERM...(This evening through Wednesday night) Issued at 318 PM CDT Sun May 9 2021 Tonight-Monday: Combination of layered moisture will keep skies generally cloudy throughout the period. Models appear to be showing typical bias of being agressive with QPF (and resultantly chances of rain) with moist low level upslope flow over the middle of KS. There is fairly decent mid level warm air advection later tonight in western KS, but this weakens as it translates east. Best chances are expected around daybreak in central KS, more so in the western half. Am anticipating more sprinkles and very patchy light rain at most. Temperatures will be held up tonight and suppressed on Monday by extensive clouds. Monday night-Tuesday: Approaching upper shortwave will induce increasingly good 700MB warm air advection late Monday night and especially on Tuesday. Tuesday morning both GFS and RAP suggest 850MB moisture and warm air advection with warm front drifting north near OK/KS border. This would support the increasing pops on Tuesday, although NAM is not so inclined. Temperatures will once again be held up Monday night and suppressed on Tuesday by extensive clouds. Wednesday: Surface high pressure will be moving through on Wednesday. Only support for precipitation comes from GFS with weak 700MB trough in area, otherwise flow below 700MB is anticyclonic, and ECMWF is anticyclonic at 700MB as well. Very skeptical there would be any precipitation. -Howerton .LONG TERM...(Thursday through Sunday) Issued at 318 PM CDT Sun May 9 2021 Fairly low confidence forecast, given NBM initialization and model track record over the past two weeks. Upper pattern transitions from modest northwest flow to zonal flow to ridging during the period. A similar transition about 2 weeks ago was not well handled, with a slower than forecast transition and much cooler than forecast temperatures. This pattern has a similar look. Due to differences between ensembles, NBM is quite generous temporally and spatially with precipitation, yet still is able to increase high temperatures 20 degrees between Wednesday and Saturday. (GFS is even more pronounced, with 30+ degree swing.) A lot of difference in precipitation is explained by how soon return flow and weak warm front moves north. Given anticipated low level moisture trajectories, suspect precipitation is over forecast, with clouds more likely than precipitation. Also suspect temperatures will be a bit slower to recover late week, although going weekend forecast high temperatures may be OK if precipitation/clouds do not materialize. -Howerton && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 711 PM CDT Sun May 9 2021 MVFR clouds are expected to continue this evening through tomorrow morning across much of the area. Scattered showers will occasionally impact terminals this evening and overnight. Expect north and northeasterly winds to continue throughout the TAF period, and becoming easterly near the very end of the period. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 46 59 47 56 / 20 20 30 50 Hutchinson 44 57 45 55 / 20 20 40 60 Newton 45 57 45 56 / 20 20 30 50 ElDorado 45 59 46 57 / 20 20 20 50 Winfield-KWLD 46 60 47 59 / 20 30 20 50 Russell 42 56 44 54 / 20 20 50 70 Great Bend 43 54 44 52 / 20 20 50 70 Salina 44 59 45 57 / 20 20 30 50 McPherson 43 57 45 54 / 20 20 40 50 Coffeyville 46 61 46 62 / 20 20 10 40 Chanute 45 59 46 61 / 20 20 10 40 Iola 44 59 45 60 / 20 20 10 40 Parsons-KPPF 46 60 46 62 / 20 20 10 40 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...PJH LONG TERM...PJH AVIATION...KMB
National Weather Service Wilmington OH
932 PM EDT Sun May 9 2021 .SYNOPSIS... Low pressure and a cold front will move east of the area by early this evening. High pressure will then build into the region through mid week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Precipitation has moved out of the ILN CWA, with a cold frontal passage bringing a sharp wind shift to the north -- and another couple hours of gusts into the 15-25 knot range. All expectations are for a gradual erosion of the remaining stratocumulus deck from north to south, though this may take most of the overnight before the clearing (or partial clearing) gets all the way to the Ohio River. Nonetheless, latest HRRR/RAP runs suggest the clearing in the northern sections of the CWA will combine with an eventual weakening of the wind flow to allow for substantial cooling into the middle 30s. Temperatures in this area have been lowered by a degree or two overnight. There is also some concern for fog development along and north of Interstate 70 after 09Z, with some spurious / inconsistent suggestions from the HRRR and SREF that this may occur. This will left out of the forecast for now, but should at least be mentioned here as a low-probability chance. Previous discussion > Low pressure and a cold front are tracking across the area and will move off to the east by early evening. Gusty winds will continue in the warm sector until this moves through. Any instability working up the front is very meager, but cannot rule out a bit of thunder as this line move across southeast counties. In the wake of the low, north winds will gust into the evening and then diminish quite a bit. As high pressure starts to build, expect clouds to decrease. Skies and winds will decrease enough for some frost to develop north and west of I-71 where temperatures will fall into the mid to upper 30s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... High pressure centered over the northern Plains will continue to ridge southeast into the region through the period with a reenforcement of cool, dry air. A weak disturbance will pass through the area during the afternoon and evening bringing a period of clouds. Once again, conditions may become favorable late Monday night for some more frost in northwest counties. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Surface high pressure is forecast to build southeast from the Great Lakes and into the Ohio Valley region through the end of th work week. This will lead to mainly dry conditions. While we will see a gradual warmup through the end of the work week as the airmass modifies, temperatures will still be below the normal readings for this time of year. Some areas of frost will be possible at night through midweek with Tuesday night looking to be the coldest as overnight lows drop into the mid 30s across much of our area. The surface high will push off to our east through the weekend with some weak mid level energy possibly moving in from the west. This will lead to some slight chance pops and a continued slight warming trend Saturday into Sunday with highs by Sunday into the lower 70s. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Precipitation has ended at the TAF sites, but MVFR ceilings are expected to persist for the next 3-6 hours. Some periods of IFR are also expected, mainly before 04Z. Ceilings are expected to scatter out, leading to VFR conditions later in the overnight hours. Winds remain somewhat gusty as of this writing (2320Z) but will diminish in intensity overnight. There is a low-end chance of some fog and low ceilings developing at KDAY, and possibly KCMH/KLCK, after 08Z. A TEMPO MVFR visibility has been added to KDAY for this, but for now the probability appears too low for any additional inclusion in the TAFs. VFR conditions are expected tomorrow, with winds remaining under 10 knots. .OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Frost Advisory from 2 AM to 8 AM EDT Monday for OHZ026-034-035- 042>046-051>054-060>062-070. KY...None. IN...Frost Advisory from 2 AM to 8 AM EDT Monday for INZ050-058-059- 066-073-074. && $$ SYNOPSIS... NEAR TERM...Hatzos SHORT TERM... LONG TERM...JGL AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Jackson MS
1009 PM CDT Sun May 9 2021 .UPDATE... Updated for evening discussion. && .DISCUSSION... A couple of storm clusters continue to migrate eastward across areas north of the I-20 corridor in an environment with sufficient instability and deep layer shear for organized severe weather. The cluster moving across west central MS is oriented more favorably to low level shear and showing signs of better organization and strengthening rear inflow supportive of damaging winds. Will maintain the current severe risk and continue the mention of heavy rainfall as well given the high convective rainfall rates continuing. Expect the threats to wind down some as we go into the overnight when instability will diminish some. /EC/ Prior discussion below: Tonight and tomorrow... A cold front is still off to the nw and slowing down from prev forecast approach. Out ahead of it, a quick disturbance is rippling across the Gulf Coast states, kicking off showers and thunderstorms. Given the cloud cover across the region that is partially due to some of the convection to the west...instability is a little somewhat inconsistent, though the near term mesoscale analysis hints at a few hours of SBCAPE values in the 2000-2500 J/kg range if the showers can tap into it. Deep layer shear is brief, but would help with steep mid level lapse rates in creating a severe weather threat, with wind and hail the main concern. Even though a tornado cannot be ruled out...the shear profiles become less concerning with time. The cold front should be invof SE AR and the northern part of the forecast area towards sunset as the lifting mechanism shifts to the leading edge of the advancing airmass. Showers and thunderstorms along the front start to advance through the forecast area into the early evening. The severe threat is conditional on several aspects...the first being how turned over the airmass is by this early afternoon convection. Also, the showers and thunderstorms in the latest runs of the HRRR and to some extent the NAMNest transition into more of a flooding/heavy rain concern as the front slows and the boundary hangs up south of I-20. By tomorrow morning, solutions diverge with the HRRR pushing the front through with the convection along the coast by morning and scattered convection behind it. But the NAMNest is a little more aggressive with convection. The flooding concern will be increasing, but the FFG in the near term is in excess of 3-4 inches in the 3 hr. So...going into tomorrow/tomorrow night... the next round of storms will potentially see a higher risk/potential headlines depending on location of the highest rainfall today/where the front slows. All in all, a stormy couple of days are forecast with a marginal risk of severe weather across the southern two thirds of the forecast area given the available moisture and series of agitated waves in the westerly flow. Monday night through Saturday... At 500mb, a mostly zonal pattern stays in place through the first half of the week... starting to pick up more of a northwesterly flow regime as a low ejects out of the nrn Rockies and dives into the Midwest. In that mostly zonal pattern, a series of disturbances ripples across the southern half of the forecast area, invof the remains of the frontal boundary from Monday evening. Supported aloft by the jet structure, severe storms once again are a concern for Tuesday and Tuesday night...but similarly to Monday...much of the available instability will be contingent on clearing/recovering the airmass. With Monday through Tuesday night having the best chances for convection with heavy rainfall in the same location along and south of I-20...a flash flood concern will be increasing... but much of that is a function of how much/where the heaviest rainfall falls this afternoon/tonight. GFS is a little quicker to clear out the precip by Wednesday afternoon...finally starting to see a quicker resolution to the stormy weather. However, the ECMWF is lingering precip through Thursday morning. High pressure builds back into the region for the end of the week, with northerly surface winds keeping the temperatures below normal for Thursday and Friday. But overnight Fri night...the ridge axis moves to the east, setting up southerly flow and a warming trend through the weekend. && .AVIATION... 00Z TAF discussion: Scattered showers and thunderstorms will continue over the area through much of the period as a cold front slowly pushes through the region. As the front approaches, ceilings will become MVFR/IFR and likely stay as such through the end of the period. Southerly winds at 10 to 15 knots with gusts to around 25 knots will become northwesterly with the frontal passage./GG/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 65 74 61 73 / 76 80 50 76 Meridian 64 76 60 73 / 81 81 43 67 Vicksburg 64 72 61 73 / 84 66 55 76 Hattiesburg 67 78 66 80 / 72 88 35 81 Natchez 66 75 63 76 / 83 88 39 79 Greenville 57 64 57 68 / 90 37 55 53 Greenwood 59 67 57 68 / 94 44 51 52 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
Area Forecast Discussion
National Weather Service New Orleans LA
921 PM CDT Sun May 9 2021 .EVENING UPDATE... Have opted to issue a Flash Flood Watch for most of the CWA through Noon Monday, the exception being the lower portions of the Louisiana coastal parishes. Convective complex over western Louisiana looks to reach the area somewhere around midnight. Seeing some indications, especially on the HRRR runs, of the complex laying out an east-west boundary somewhere near Interstate 10 for at least a few hours late tonight and Monday morning. Precipitable water values are forecast to increase from their current 1.4 inches on the LIX 00z sounding to around 2 inches by sunrise Monday. The LCH 00z sounding was already at 1.8 inches. While current QPF forecast is for 1-3 inches through midday tomorrow, if the boundary sets up east-west, rain amounts could be considerably higher in some areas, where echo training occurs. The morning rush hours in the metro areas could be significantly impacted by heavy rainfall. Also still a severe weather threat, with Severe Thunderstorm Watches to our northwest and west for the remainder of the evening hours, and certainly a potential for watches to be extended into our area sometime around midnight or so. As the area of heavy rain threat becomes better focused over the next few hours, will probably reconfigure somewhat with the 4 am forecast package, but raising public awareness of the threat necessitated issuing the watch now. 35 && .PREV DISCUSSION... /issued 317 PM CDT Sun May 9 2021/ SHORT TERM (Tonight through Tuesday Night)...A zonal flow regime will be in firm control of the area through Tuesday night. A series of fast moving upper level jet streaks and associated vorticity maxima will sweep through the Lower Mississippi Valley on the back of this zonal flow pattern. In the low levels, onshore flow will continue to advect moisture into the region. Lapse rates on the order of 6.0C/km should be sufficient to produce a fair degree of instability through the period, and expect to see mixed layer CAPE values of 1500 to 2000 J/KG each day. Given the forcing and instability in place, several rounds of convective development are anticipated through Tuesday night and fairly high POP in the likely to categorical range is forecast each day. The primary concern from the multiple rounds of convective activity through the period will be locally heavy rainfall and have storm total QPF values of 2 to 3 inches forecast through Tuesday night. If storms begin to train over the same area, some locally higher amounts will be possible. A flash flood watch has not been issued yet as there is still some uncertainty in exactly where the highest threat will set up, but a watch will likely be issued by tomorrow or Tuesday. There will also be a limited risk of an isolated severe storm forming, but shear profiles remain weak through the period. Model soundings do indicate a favorable setup for a few downburst events during the afternoon hours both tomorrow and Tuesday, and an isolated damaging wind event cannot be ruled out. Given the weaker lapse rates and limited directional shear anticipated, the threat of hail and tornadoes will be very low. LONG TERM (Wednesday through Saturday Night)...The zonal flow pattern will continue to bring rounds of thunderstorms to the area on Wednesday, but a northern stream trough axis and associated front will bring about a pattern change from Thursday onward. Initially, the pattern will be little different from that seen on Monday and Tuesday with rounds of convection being driven by upper level jet dynamics and passing regions of increased omega. Precipitable water values will remain elevated and instability will be in place to support the convection. The only significant change on Wednesday is that a more stable cold pool will likely be in place in the low levels. As a result, the convection should remain largely elevated and the risk of severe storms will be greatly diminished. However, with precipitable water values running around 2 inches, locally heavy rainfall will continue to be a concern. An additional 1 to 2 inches of rain could fall Wednesday into Wednesday night and this will keep a risk of flash flooding in place. Fortunately, the period of unsettled weather will begin to end on Thursday as the northern stream trough axis and attendant cold front sweep east of the area. As northwest flow develops, a drier and much more stable airmass will begin to advect into the area. The dry air will initially advect into the mid and upper levels, and some lingering post-frontal stratus is expected through Thursday afternoon. By Thursday night, this stratus deck should clear out as deep layer subsidence develops. These clear skies will then persist through Saturday night as a deep layer ridge axis builds over the Gulf South. Weak cold air advection into the region will also occur and this will keep a few degrees cooler than average on Thursday and Friday. Given the clear and dry conditions in place, a large diurnal range is anticipated. Highs should warm into the upper 70s and lows should dip into the 50s. By Saturday, some modification of the airmass is expected with highs climbing back to more normal levels in the lower to middle 80s and lows dipping into the 60s. AVIATION...The 00z TAF will indicate deteriorating conditions late tonight into tomorrow morning as a complex of showers and thunderstorms moves into the area. Prevailing MVFR ceilings and visibilities will develop at most of the terminals with periods of IFR conditions possible as heavier downpours move through. These showers and thunderstorms will likely persist into the afternoon hours. PG MARINE...Onshore flow will be the rule through Tuesday night as the region remains sandwiched between a low to the northwest and a high to the east. Winds will likely remain elevated in exercise caution range of 15 to 20 knots tonight, but should ease back to 10 to 15 knots tomorrow through Tuesday as the high to the east weakens. A front will push through the waters on Wednesday and winds will shift to the northeast. This northeast flow will persist through Friday and will likely increase to 15 to 20 knots as slightly cooler air advects over the warmer Gulf waters. Seas will turn choppy at 3 to 5 feet as these winds persist. PG && .PRELIMINARY POINT TEMPS/POPS... MCB 67 81 66 79 / 80 90 40 90 BTR 71 84 69 82 / 70 80 40 80 ASD 70 83 69 83 / 70 80 40 70 MSY 72 84 72 83 / 60 70 40 60 GPT 71 80 70 80 / 60 80 40 70 PQL 69 81 68 82 / 60 80 40 70 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Flash Flood Watch through Monday morning for LAZ034>037-039- 046>050-056>061-063>065-071-072-075>078. GM...None. MS...Flash Flood Watch through Monday morning for MSZ068>071-077- 080>082. GM...None. && $$
Area Forecast Discussion
National Weather Service Pendleton OR
842 PM PDT Sun May 9 2021 .UPDATE... The isolated to scattered showers from earlier have mostly dissipated and the remainder should do so over the next few hours as high pressure build in overnight and into Monday. Made adjustments to pops and cloud cover and tweaked temps where needed. Otherwise forecast looks on track. && .AVIATION... 06Z TAFS...High pressure will be building in overnight into Monday and VFR conditions are expected. Winds will continue to drop off overnight and speeds of 10 kts or less are expected through the period. && .PREV DISCUSSION... /issued 417 PM PDT Sun May 9 2021/ AVIATION... 00Z TAFS...VFR conditions are expected through the TAF period and beyond as high pressure will build in through the week. Some gusty winds are possible, especially at RDM and DLS through the evening, but then all winds should be 10 kts or less for the remainder of the period. Otherwise, any low to mid level clouds will give way tonight to mainly just cirrus and mostly clear to clear conditions. PREV DISCUSSION... /issued 306 PM PDT Sun May 9 2021/ SHORT TERM...Tonight through Tuesday night. Latest day cloud phase imagery shows cu across much of the area, some deep/thickening apparent in parts of central OR and east slopes of the Cascades. Meanwhile, latest water vapor imagery shows a upper level ridge building in the eastern North Pacific. Main weather concern is potential for isolated showers, maybe a rumble of thunder, this afternoon- evening in the northeast mountains and more so Wallowa county tomorrow. Latest HREF shows limited development along with recent HRRR runs so confidence increasing in that the areal coverage will be low. That said, thinking some light rain showers cannot be ruled out, mainly over the northeast mountains today. Scant instability and marginal environment in place so current thinking is potential for thunder is low. Otherwise, the upper ridge evolves eastward gradually the next 48 hrs that will continue the current warming trend. Temperatures will rise each day with highs peaking in the mid 70s to around 80 by Tuesday, about 8 to 10 degrees above normal. This will coincide with light winds in the period and generally low sky cover Monday and Tuesday. LONG TERM...Wednesday through Sunday. Fairly benign pattern continues at the start of the long term period with a somewhat progressive and zonal flow pattern dominating through Thursday. This is followed by increasing variability and uncertainty Friday and this weekend with respect to the large scale pattern. Broad upper level ridge affecting the western CONUS to start the period early Wednesday with the pattern staying fairly zonal overhead through Thursday. That said, ensemble and deterministic guidance start to see increasing spread Friday and beyond with respect the development of the upper-level trough in terms of its amplitude and location, more so this weekend. Confidence has increased in a upper-level trough evolving and deepening in the eastern North Pacific offshore British Columbia and the PacNW Friday then affecting the region Saturday. However, variability exists in how deep and its timing for this weekend. Ultimately, sensible weather impacts may be limited, though anticipate breezier conditions this weekend, especially in the Gorge and Kittitas valley. Clustering scenarios show there could be some unsettled conditions with a deeper trough scenario with increased precip chances, however, confidence is low in a deeper/wetter scenario. With moderate confidence in timing of the trough, appears well above normal highs will persist through at least Friday, about 10-15 degrees above normal. Highs generally then in the low to mid 80s, warmest in the WA Basin. AVIATION...18Z TAFS...Latest satellite imagery shows stratocu across central OR and the northeast mountains, of which some low-end MVFR ceilings (2-3 kft) are present, including at the KBDN terminal. These ceilings should rise and become low-end VFR (less than 7 kft) late this morning/early afternoon. Otherwise, expect some increase in sky cover from cu over south central WA and the Basin where there is presently high clouds overhead. Generally light breezes will prevail the next 24 hrs, except modest winds with gusts as high as 25 kts mainly in the Gorge and Kittitas valley. Light winds are then expected overnight. Could see some widely isolated shower activity in the northern Blues today too but anticipate limited impacts with that, mainly between 21Z-03Z. && .PRELIMINARY POINT TEMPS/POPS... PDT 40 69 40 75 / 0 10 0 0 ALW 44 73 45 78 / 0 10 10 0 PSC 43 76 47 81 / 0 0 0 0 YKM 41 74 42 78 / 0 0 0 0 HRI 43 75 42 80 / 0 0 0 0 ELN 41 71 40 76 / 0 0 0 0 RDM 30 68 34 74 / 0 0 0 0 LGD 35 64 37 71 / 0 20 0 0 GCD 35 67 38 74 / 0 0 0 0 DLS 46 74 46 79 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...77 LONG TERM....80 AVIATION...77
Area Forecast Discussion
National Weather Service Phoenix AZ
425 PM MST Sun May 9 2021 .UPDATE... Updated Aviation && .SYNOPSIS... Dry conditions and generally clear skies will prevail over the next few days as a weak weather system remains situated well north of our region. Temperatures through early week are forecast to be slightly above normal while daytime breezy conditions will be common. Warmer temperatures for the latter half of the week are expected as daytime highs are likely to top the 100 degree mark across the lower deserts by Thursday. && .DISCUSSION... A broad region of upper troughing is in place over portions of the CONUS and eastern Canada with a subtropical ridge centered over southern Mexico. Our forecast area lies within zonal flow in between. Dry disturbances/short waves continue to move within that flow across the desert southwest with one currently moving through today and another for Monday. Those features will help enhance the afternoon breezes a little bit. Meanwhile, over the northeast Pacific is a high amplitude ridge and to our east, a backdoor cold front is pushing against the southern Continental Divide. Far to the south-southeast, over 600 miles south of the southern tip of Baja Mexico, is Tropical Storm Andres. It is forecast to weaken to a Depression during the day Monday and then continue weakening as it drifts west. It may be a partial contributor to some moistening of eastern AZ later this week but otherwise will be a non-factor for our forecast area. In the short term, an X-factor in terms of the sensible weather will be wildfire smoke with at least 4 active fires over/near south- central AZ. The vast majority of the smoke will be above the surface and get blown east-northeastward. But, as nighttime develops and the mixed layer becomes very shallow, there may be some smoke that drains into some populated areas. However, the fires will be a lot less active at night. The HRRR smoke tool has done a pretty good job initializing the fires of note and it depicts only narrow corridors of near surface smoke. Made some manual adjustments in the digital forecasts to broaden out the locations that may be affected to try to account for some uncertainties. The portion of our forecast area that will mainly be affected will be southern Gila County. Otherwise, for south-central AZ, there will be some lofted haze most noticeable in the morning with a low sun angle. As for temperatures across the CWA, they will be a few degrees above normal through Tuesday. The northeast Pacific ridge builds inland and leads to a warming trend Wednesday and Thursday with little change Friday. That will mean highs on the lower deserts in the 100-102 range Thursday and Friday. There may be some moisture that slips into portions of Arizona from the east aided by a reinforcement of the backdoor front. However, EPS and GEFS means keep QPF out of the forecast area and limited primarily to a corridor from the White Mountains to the San Francisco Peaks Wed-Fri. Late in the week and over the weekend, the ridge begins to get displaced by a Pacific trough. As might be expected, there are differing solutions on how quickly the trough moves in and how deep it will be. This is evident in the WPC Cluster analysis where each of the modeling systems has members in more than one cluster. For now, things look dry for our forecast area and we temperatures highs still look to be well into the 90s on Sunday. But, anticipate breeziness to pick up. && .AVIATION...Updated at 2325Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Under mostly clear skies, winds will be fairly similar in both magnitude and timing of wind shifts to the past several days. Confidence is moderate that a more prolonged cross runway southerly winds could exist around noon, albeit with speeds under 10kt. After the switch to a SW component is accomplished by midday Monday, gusts around 20kt may be somewhat more pronounced than the past couple days. Otherwise, smoke from nearby wildfires has been less expansive this afternoon and should not contribute to visibility issues. Southeast California/Southwest Arizona including KIPL and KBLH: No major weather issues will exist through Monday evening under clear skies. Winds will favor a southerly component at KBLH with some occasional gustiness. Confidence in wind shifts between SE and SW at KIPL is much lower depending on how far any sundowner winds to the west spread into the Imperial Valley. && .FIRE WEATHER... Wednesday through Sunday: Temperatures on Wednesday will warm up into the upper 90 to near 100 degrees with additional warming expected during the latter part of the week. By Thursday, high temperatures at most lower desert locations will be at, or near, 100 degrees with little change through Saturday. There will be a bit less breeziness in the Tue-Thu time frame compared to the preceding weekend followed by an uptick in winds Friday through Sunday. Minimum RHs will be quite low for the latter half of the week with readings in the 5-10% range. Maximum RH values will be around 20-30% Wednesday and Thursday before dropping to around 15-25% for the end of the week. Locally higher maximum RHs upwards of 40-50% will exist across parts of Imperial and Yuma Counties. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...AJ AVIATION...MO FIRE WEATHER...Smith/Kuhlman
Area Forecast Discussion
National Weather Service Reno NV
202 PM PDT Sun May 9 2021 .SYNOPSIS... A slightly unstable airmass will lead to buildups or even a light shower over the Sierra late today. A brush by cold front will then bring breezy north winds to the region tonight into Monday. Temperatures will warm to well above normal through Friday as high pressure overspreads the Great Basin. Unusually dry air will allow for good cooling at night however. Pacific low pressure could bring breezy winds, cooler temperatures, and a chance of showers this coming weekend but forecast confidence is fairly low this far out. && .DISCUSSION... * Recent runs of the HREF have been generating buildups and even isolated showers over the Sierra from Truckee to Bridgeport late today. Thus far development has been mainly just flat Cu and the Reno sounding from this morning looked rather unimpressive. Can`t entirely rule out some virga or even a shower, but for now will leave forecast dry with a 10% chance over the Sierra. * Northerly winds will kick up tonight into Monday associated with a brush by cold front. Not a major wind by any means but gusts up to 30 mph could result in blowing dust and localized fire weather concerns in W Nevada and lower elevations of the E Sierra. Gradient is sufficient that winds will likely stay up or even increase overnight tonight as seen in latest HRRR and NAM3. So don`t be surprised to hear things rustling around outside overnight. * Temperatures warm to well above normal Tuesday through Friday as broad upper high moves over the Great Basin. Warmest days likely Wednesday and Thursday with full sunshine and light W/SW afternoon winds to help with mixing/warming. Friday could be as warm, but breakdown of the upper ridge and late-day increase in clouds seen in NBM could be enough to temper that slightly. Record highs are largely out of reach for W Nevada however in mountain communities there`s about a 20-40% chance of new records Wed-Fri. Unusually dry air will help many areas cool nicely at night to help offset those warm afternoons. * Heat Risk data show a yellow/low risk during this period, focusing potential heat health impacts on extra sensitive groups and those outdoors for long periods of time. Along with that dry air, have a good hydration strategy this week. * Next weekend is where the largest forecast variability exists, as most ensembles bring in a Pacific upper trough. Some ensemble clusters show a noticeably cooler and breezier scenario, with a few showers Saturday-Sunday while many others keep us dry with continued warm temps. This is made most clear in NBM highs for RNO Saturday-Sunday ranging from roughly 66 to 87 at the 10th and 90th percentiles. No favored scenario at this point, so keep your options open for next weekend. Will continue the small chance of showers and cooler temps in the ongoing forecast. -Chris && .AVIATION... A dry boundary will push through the region today and overnight into Monday bringing periods of breezy north to northeasterly winds. Gusts will generally be around 20kts except for a brief period overnight when the boundary pushes through north to south; gusts up to 30kts 03-09Z. Best shot for these winds at KRNO will be in the 04-07Z time frame. After 09z ridge easterly ridge winds increase creating turbulent conditions and crosswinds for Sierra terminals. Surface flow across the region remains easterly through Tuesday before switching more westerly by Wednesday. Otherwise, conditions will remain dry with little chance of precipitation through the week. The next chances of precip could be next weekend as another trough pushes towards the region. With a trough moving into the region towards the end of the week, expect another round of breezy to gusty winds. Boyd && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Blacksburg VA
946 PM EDT Sun May 9 2021 .SYNOPSIS... A low pressure system will track northeast through the Ohio Valley tonight and will slowly push a cold front across the Mid Atlantic region on Monday with showers and thunderstorms. High pressure, along with drier and cooler weather is expected for Tuesday and Wednesday. The chance of precipitation returns for the end of the week as active storm systems track well to the south. && .NEAR TERM /THROUGH MONDAY/... As of 930 pm EDT Sunday... Minor adjustments to timing/placement of showers through the overnight period, but overall flavor of the forecast remains the same. Previous discussion... Another round of showers pushing in from the west and moving east overnight. RAP is showing some instability over northern NC and perhaps western VA associated with the short wave kicker/main frontal surge, so have isolated thunderstorms for that time period. Expect the cold front to be south of Route 460 by afternoon and the time that thunderstorms develop along and ahead of the boundary. The probability of precipitation will move south but not clear northern North Carolina before 8PM/00z. Warm air advection and rising dew points will keep temperatures mild overnight. As the cold front comes through a cooler air mass pushes south into the area. Little rise in temperatures is expected Monday in southeast West Virginia and the Alleghany Highlands. Ahead of the front highs will still warm into the 70s. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 115 PM EDT Sunday... Unseasonably Cool Weather Persist Through The Work Week Monday`s front will still likely be lingering along the southern edge of the CWA before cool high pressure starts to strengthen and push into the area, giving the front the final push it needs to move out of the region. Following the front`s departure Monday night, cooler weather settles in with high pressure persisting for several days. That said, a tightening pressure gradient Tuesday will aid in yet another windy day here in the Mid-Atlantic region, particular for those along and west of the Blue Ridge. While originally it looked like a southern stream based low would slip into the area Wednesday, high pressure trucking eastward near the Great Lakes should dominate and block precipitation from making it up into the Mid-Atlantic. Instead, convection will remain confined to the southern states, with only a few showers possibly slipping up into the NC mountains and piedmont now. Thursday it appears that our dry streak luck finally starts running out with discrepancies on timing of a weak disturbance bringing lighter rain chances to the area. At the moment, the greatest concentration of these showers would be in the western half of the CWA. With discrepancies in timing occuring between models, have settled with a mid point bringing greatest POPs through Thursday night into Friday. All the while, the big talking point of this part of the forecast will be the abnormally cool weather with highs running 5 to 15 degrees below normal. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 130 PM EDT Sunday... Cooler Weather Continues With Additional Opportunities At Light To Moderate Rain... As mentioned at the end of the short term discussion, there are some discrepancies concerning a weak disturbance Thursday into Friday. Timing remains an elusive detail to when the greatest POPs for those system will be. For now, the forecast represents a middle ground bringing highest POPs Thursday night into Friday. Following the Thursday Friday system, high pressure is expected to make a return. How long we remain dry thanks to high pressure becomes the next big question of the long term part of the forecast: guidance becomes very clouded with ensemble members remaining highly variable about our next system. For now given our recent active pattern, it will probably go without saying that there will likely be follow up disturbances with no sign of a major pattern shift available. Our next shot at rain could be as early as Sunday morning, but will have to wait and see once better agreement amongst guidance can be achieved. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... As of 745 PM EDT Sunday... Two periods of showers and isolated thunderstorms are expected in the mountains tonight. The first area is moving through currently. There have been some brief gusts in the 25-35 kt range, more commonly around 20-25 kts, especially at higher elevations as a strong LLJ moves through. MVFR visibility is still likely with any of the heavier rains. Thunderstorms are not expected except maybe with the second round between 03 and 12Z. Winds begins to diminish overnight and will be much lighter after 12Z/8AM Monday. Showers will continue Monday morning as a cold front sinks south over the Mid Atlantic region. Thunderstorms will redevelop in the afternoon along and ahead of the front in North Carolina and extreme southern Virginia. Confidence was low reguarding any impact at KDAN before the 18Z/2PM end of the TAF forecast period. Behind the front ceilings drop to MVFR then IFR with patchy MVFR fog. Have KLWB and KBLF both down to at least IFR around 12Z/8AM and little improvement is expected for the rest of Monday morning. Average confidence in ceiling, visibility and wind. Extended Aviation Discussion... High pressure builds in for Monday night and Tuesday with dry and continued rather cooler temperatures. It appears that moisture will be shoved far enough south for midweek to allow the dry/mostly VFR conditions to continue until Thu/Fri, when a developing midwestern short wave will bring an increasing threat for showers and thunderstorms at the end of the week. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...MBS/SH/AMS SHORT TERM...RR LONG TERM...RR AVIATION...RAB