Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/29/21

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
826 PM MDT Fri May 28 2021 .UPDATE... The Severe Thunderstorms Warning has been cancelled as convection has moved south and east out of the forecast area into Eddy and Lea Counties and into the TX Panhandle. Updated zone forecast is out. Thanks to all of the storm reports sent in for today`s severe weather! 24 && .PREV DISCUSSION...521 PM MDT Fri May 28 2021... .AVIATION... 00Z TAF CYCLE Scattered thunderstorms continue across eastern New Mexico this afternoon. The threat for strong to severe storms will continue through about 03Z when the storms should then move into west TX. Main threats continue to be heavy rain, frequent lightning, large hail, and damaging winds. Outflow boundaries propagating westward along with sufficient low-level moisture will cause low-clouds with MVFR to IFR ceilings to redevelop for areas along and east of the central mountain starting around 06Z and continuing through mid- morning. The east canyon wind is still expected at KABQ, but wind speeds should remain below 35 knots. Therefore, an Airport Weather Warning is not anticipated. 15 && .PREV DISCUSSION...314 PM MDT Fri May 28 2021... .SYNOPSIS... Strong to severe thunderstorms will be the rule during the afternoons and evenings in eastern New Mexico this evening through at least Memorial Day. Best chances for afternoon and evening showers and thunderstorms in the Rio Grande Valley and points west will be on Memorial Day. High temperatures on Saturday will be near average, cooling to below average Sunday and into early next week. Slight chances for afternoon and evening showers and thunderstorms will remain in the forecast through much of next week. && .DISCUSSION... .SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)... East to southeast flow at the surface continues for areas along and east of the central mountain chain, complements of last night`s backdoor cold front. Upslope flow has allowed for storms to develop early this afternoon across the northern high terrain, and they are slowly propagating east-southeast onto the lower elevations. These storms will be entering an unstable and sheared environment which will allow them to intensify through this evening. Aloft at 500mb, westerly flow is present while farther up at 300mb, flow is more northwesterly. While flow aloft is fairly week with only about 10 to 20 knots at 500mb, the curved hodograph indicates plenty of directional shear. The latest SPC mesoanalysis indicates plenty of instability as well with 1000-2000 J/kg of MLCAPE from roughly San Miguel County southward through Lincoln and Chaves counties. This environment will support severe or supercell thunderstorms with the primary threats being large hail and damaging winds. These storms should develop into multi-cell clusters or linear segments as they approach the NM/TX border this evening, and both the latest HREF and HRRR guidance indicate the severe weather threat should be over by 03-04Z as the storms exit into west TX. Outflow from these storms will surge westward tonight, helping to reinforce low-level moisture as well as produce an east canyon wind in the middle RGV similar to last night. Surface winds across the east will veer more southeasterly on Saturday, limiting the upslope component that`s present today. However, as an H5 low starts to take shape to our west, a mid-level jet streak will be steered over the CWA. While directional shear is reduced, speed shear increases thanks to the jet streak. Additionally, upper-level divergence is enhanced across the northeast corner of the state which will be within the left exit region of the jet. With plenty of instability remaining in place, Saturday will feature another round of strong to severe storms again for the eastern portions of the CWA, particularly the northeast where the latest SPC Day 2 Outlook highlights a slight risk. The other concern for Saturday will be the possibility for heavy rainfall across the northeastern plains as well as areas along the NM/TX border. By Saturday night, a shortwave disturbance over southern CO will interact with another backdoor cold front. This area of convergence combined with increased instability along the front will help additional convection to develop. There also high confidence with more than sufficient moisture with PWATs near to even exceeding an inch. These PWATs are above climatology which adds to the heavy rainfall confidence. Models are in fairly decent agreement with the potential for heavy rainfall totals although there are differences in placement. By Sunday morning, there is the potential for some locations to see upwards of 2-3" of rain which may produce flash flooding. LONG TERM...(SUNDAY THROUGH THURSDAY) Sprawling surface high pressure centered near the Great Lakes will keep a southeasterly return flow going across eastern NM Sunday. At the same time, a weak upper-level low over far southern CA is forecast to slowly slide southeastward over northern Baja and northwest Sonora during the day Sunday. This upper-low results in surface low pressure developing over west-central NM Sunday afternoon. Another round of strong to severe storms is likely across much of eastern NM Sunday afternoon/evening with a strong westward push of moist rain-cooled air surging westward Sunday night. Strong east winds are forecast for the RGV Sunday night into Monday morning. GFS and ECWMF agree that Gulf moisture associated with this surge will be plenty deep to not get scoured out via afternoon mixing west of the central mountain chain. Memorial Day still looks like the best day for wetting showers and thunderstorms in the RGV and points west. Out east, another round of strong to severe storms is forecast underneath increasing southwest flow aloft ahead of the above mentioned upper low. Upper-level trough axis slides east of NM Tuesday. Enough residual low-level moisture remains for a round of afternoon mainly mountain convection Tuesday. The northern mountains and northeast highlands/plains stand the best chances for convection Wednesday thanks to atmospheric stretching (deformation) between a deep upper- level trough to the east and a building high pressure ridge to the west. 15/33 && .FIRE WEATHER... There are currently no critical fire weather concerns over the next week. A very active pattern through the holiday weekend will lead to daily rounds of thunderstorms, especially across eastern NM. Storm coverage this weekend will favor areas along and east of the central mountain chain. Across the west, dry conditions prevail with minRHs in the single digits, however, winds will remain relatively light. Chances for wetting precipitation increase for central and western NM Monday and Tuesday as low-level moisture being pushed westward to the Continental Divide should result in an uptick in storm coverage. Chances for storms and wetting precipitation will gradually trend down by the middle of next week as winds continue to remain light. 15 && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
752 PM MDT Fri May 28 2021 .UPDATE... Issued at 752 PM MDT Fri May 28 2021 High based showers with a few weak storms mixed will continue to progress eastward through the evening. A couple may linger past midnight across the far eastern plains. Tweaked PoPs and sky cover to line up with current trends. Latest HRRR runs bring low clouds back to the Front Range Saturday morning, mainly after sunrise. This looks on track with low level moisture increasing behind a cold front. Increased cloud cover Saturday morning for this. && .SHORT TERM...(This evening through Saturday) Issued at 327 PM MDT Fri May 28 2021 Shallow cumulus clouds continue to fester over most of the higher terrain this afternoon, but we`ve yet to see any sustained updrafts develop so far. Cloud depths have increased a little in the past hour or so across far southern Jefferson county and forecast guidance continues to show at least a few weak showers/storms developing later this afternoon. We`ll maintain slight chance for storms across much of the area, with storms remaining very isolated. The severe threat is very low, but a few of the stronger showers could produce some gusty winds this evening. Showers should dissipate by early tonight. The rest of the overnight hours should be pretty quiet with party to mostly cloudy skies. Lows will remain in the low 50s for the plains and the mid 30s for most of the higher terrain. Tomorrow will mark the start of a cool and moist weekend for most of northeastern Colorado, as a slow and weak trough axis moves across the region. A weak frontal push should come through the area tomorrow morning, with moist northeasterly flow continuing through most of the day. With weak upslope flow extending through roughly 700mb and increasing (but weak) instability... characterized by a long skinny MLCAPE profile... we should start to see convection develop across the higher terrain during the early afternoon hours, with activity spreading into the plains shortly after. The modest CAPE values over our Foothills/urban corridor should limit heavy rainfall potential a bit, though forecast PWATs remain near the 90-95th percentile for this time of year. Storm motions tomorrow should also be relatively slow given the weak flow aloft. Though the overall flash flood threat will be fairly low, there are some concerns with the Cameron Peak and Calwood burn areas. In addition to the potential for heavy rains across the Foothills, there is also a severe weather threat across our far eastern counties tomorrow afternoon. Forecast guidance shows at least a few storms developing off the Palmer Divide moving into the far eastern Plains by the evening. There is some question of how unstable the airmass ahead of these storms would be, with most guidance suggesting about 1000-2000J/kg of MLCAPE. As mentioned previously, flow aloft is quite weak, but there is enough directional shear to promote a marginal severe threat. The primary threat would likely be large hail, with a few strong wind gusts also possible. Severe threat should quickly diminish by about 9PM with just a few scattered showers and storms left. .LONG TERM...(Saturday night through Friday) Issued at 327 PM MDT Fri May 28 2021 The big questions for this forecast involve details of the precipitation as the upper trough slowly moves across Colorado Saturday night through Monday. Unfortunately, while the models are in pretty good agreement on the big picture, there`s little agreement on details. What we do know is that the air mass will saturate along the east slope of the Front Range with persistent but weak upslope and lift by Sunday morning, and across the rest of eastern Colorado as the day goes on. The best lift will be over the mountains late Sunday and across the plains Sunday night. There`s agreement that mainly light winds and little temperature gradient will keep large scale QG forcing weak, but a deep neutral layer will also allow a good response to the lift that we have. Without much cold advection, the snow level remains high, probably above 10,000 feet though some models have a little more cooling in their areas of heavier precipitation. The closest thing to a focus is easterly winds against the east slopes of the Front Range, but the wind speeds are 10-15 knots at best at the surface and become weaker or less easterly with height. There`s also good agreement that we maintain some westerly flow at 500 mb, though it gets down to 10-15 knots in some models early Sunday before increasing again. What we don`t know is where any focus would be. Lacking this, we get a prolonged period of mainly light rain, possibly moderate rain for a few hours as that band of synoptic scale lift comes over. No doubt there will be some smaller scale feature such as a surface boundary on the plains or a weak eddy or shear zone in the low to mid level flow that may be tied to earlier convection elsewhere that will provide one or two foci for localized heavier rain. This is most likely to be an issue Sunday afternoon and evening when it won`t take much to produce a pocket of deeper more productive convection. But each model picks a different place and time, ranging from Pikes Peak to Larimer county and Sunday morning through Sunday evening. So we`re not able to get any more focused with a possible flood threat, and this might not change until this feature develops. Outside of a possible focus, there`s agreement on rainfall amounts generally between 0.5 and 1.5 inches with the heavier amounts in the foothills and just east. Most of the models do produce an area that gets over 2 inches, but in bullseyes in different places. So the flood threats, from most likely to least likely are: 1. Steady rain in the new burn areas east of the Front Range Sunday that produces an inch over a few hours, enough for minor flooding. 2. Slow moving storms over the burn areas that are localized but produce an inch of rain in an hour. This will likely happen somewhere, but will it be over a burn area? 3. Slow moving storms over the plains that produce a couple inches of rain in a few hours. Plains storms will probably wind up moving into the inflow eventually, making this less likely. 4. Thunderstorms west of the Front Range will have less moisture to work with, but will be slow moving and could have stronger updrafts. There is a low risk of storms producing an inch of rainfall in an hour in that area on Sunday afternoon. Monday there`s some drying coming in from the north, but that could just allow for enough heating to redevelop convection. Still slow motions, low flooding threat, and upslope winds. After that, there`s a warming and drying trend with the models with about a day`s difference between models on how quickly it warms up. There`s a bit of a trend toward a slower warm up which could keep us in the 70s with low grade storm activity through Thursday, where the more aggressive operational GFS has us in the 80s and dry by Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 752 PM MDT Fri May 28 2021 The threat for wind shift from showers will continue to decrease through the evening hours. By 06Z, southerly drainage winds are expected. A cold front will push through around 12Z and increase low level moisture. Low clouds with ceilings of 500 will be possible at KDEN and KBJC. The best time for this will be 13-17Z. With increased moisture over the area, there will be better chance for showers and thunderstorms Saturday afternoon and evening. && .HYDROLOGY... Issued at 327 PM MDT Fri May 28 2021 Flash flooding threat will be negligible tonight with no precipitation expected over the burn areas. Flooding concerns increase during the late morning and afternoon hours tomorrow as scattered showers and storms develop over the Front Range/Foothills. Above average moisture and slow storm motions could promote heavy precipitation rates, but instability is rather weak. Still, any slow moving storm that develops over burn areas could pose a threat for some flash flooding. Most flooding concerns will be contained to burn areas on the east side of the divide. Widespread light to moderate rainfall is expected on Sunday. There is a threat of localized heavy rain that could cause flash flooding in the new burn areas. The threat is greatest on the Cameron Peak and Calwood burn scars on Sunday afternoon. Elsewhere there is a lower threat of flooding. There may also be some minor flooding from prolonged steady light to moderate rainfall on the new burn scars from Saturday night through Sunday night or Monday morning. On Monday there will be a lower risk, but still some threat of flooding on the Cameron Peak and Calwood burn scars. After that, storms will likely be weaker or moving faster and the threat of flooding will be much lower for several days. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Meier SHORT TERM...Hiris LONG TERM...Gimmestad AVIATION...Meier HYDROLOGY...Hiris/Gimmestad
Area Forecast Discussion
National Weather Service Charleston SC
1016 PM EDT Fri May 28 2021 .SYNOPSIS... A cold front will push through the area Saturday night, followed by high pressure from the north into the middle of next week. The high will then move further offshore late in the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Early this evening: Regional radar imagery shows a line of convection that stretches across southeast Alabama into central Georgia and the Upstate of South Carolina. The overnight is expected to be dry and the forecast continues to follow the HRRR and RAP which both show the upstream convection dissipating before it reaches the interior zones of the forecast area. We have maintained rain chances in the 20 percent range across Allendale, Screven, Jenkins, Bulloch, and Candler counties around sunrise Saturday. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Saturday and Saturday night: A deep, but positively tilted trough will develop across the Ohio and Tennessee Valley Saturday, then move into the area at night as it becomes more neutrally oriented. At the surface, a northeast to southwest aligned cold front will drift through the Southeast, reaching the forecast area during the evening, and passing offshore before midnight. The front has a slow progression into and through the area initially since it is generally parallel to the flow aloft, and there is expected to be at least one wave of low pressure forming along the front over the Midlands and/or Pee Dee of South Carolina. While we can`t rule out a few showers and t-storms along the northwest tier early on with a weak short wave, much of the morning will be under the influence of subsidence and NVA in wake of this feature. The better chances for convection will come in the afternoon and the evening, as the front draws a little closer and there is the interaction of boundaries with the sea breeze that looks to reach close to or a bit east of the I-95 corridor. Deep layered shear isn`t overly impressive and MLCAPE looks to be only around 1000-1500 J/kg. Given quite a bit of dry air above 600- 700 mb, the strength of the updrafts will be somewhat curtailed. Thus we have gone no higher than 40% PoPs. But it looks to be the first rainfall for many places in over two weeks, albeit generally less than 1/4 inch. Where there is an interaction of boundaries the updrafts could tap into some of that drier mid level air, and maybe result in an isolated non-zero severe risk. Convection will wane quickly from west to east at night, as the cold front pushes into the ocean, and a post-frontal trough moves in the South Carolina counties overnight from the north. Temperatures look to peak close to 90F everywhere inland from the barrier islands, and with the arrival of a somewhat cooler and drier air mass after midnight, lows will fall to the upper 50s and lower 60s most places inland; middle 60s along the coast. Sunday through Monday: The trough aloft passes through on Sunday and is followed by zonal flow on Monday. Simultaneously at the surface, high pressure builds from the north Sunday, then shifts into the immediate Atlantic waters Monday. The lack of forcing and moisture will preclude any mention of rainfall. It`s a noticeable change in air mass from what we`ve recently had, and the resulting temperatures will end up below climo. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... High pressure building near the coast and over the Atlantic will block any upstream cold fronts from getting this far southeast through the entire week. The zonal flow aloft will temporarily give way to ridging, before the next trough develops far to the west and northwest Thursday and Friday. The first half of the week looks to have minimal forcing for ascent and/or moisture, but some better forcing and moisture arrive by later in the week. For now we have no rainfall in the forecast through Tuesday night, small chances Wednesday along the sea breeze, then higher chances Thursday and Friday. Thermodynamics and shear aren`t that impressive, so the severe potential looks quite low at this stage. Temperatures will climb to near or even slightly above climo given 850 mb temperatures and low level thickness near or above average for early June. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected to prevail through 00z Sunday. The main forecast challenge will be the potential for showers and thunderstorms Saturday afternoon. Isolated to scattered showers and thunderstorms are anticipated across the area, but confidence in direct impacts is low. For now, have introduced a VCSH at KCHS, KJZI, and KSAV beginning around 18-19z. Can`t rule out some brief reductions in visibility as showers and thunderstorms pass through, but details including timing and likelihood will have to be worked out with subsequent TAF issuances. Southwest winds could gust up to around 20 knots in the afternoon. Extended Aviation Outlook: VFR conditions are expected to prevail. Diurnal convection could occur Wednesday, mainly on the sea breeze. && .MARINE... Tonight: The local waters will sit in a relatively tight southwest to northeast pressure gradient area ahead of a cold front. This setup will keep southwest flow elevated through the night, mainly in the 15-20 knot range. The zone with the best chance for frequent 25 knot gusts will be the Charleston County waters and a Small Craft Advisory has been issued through 8 am. Seas will increase through the night, becoming 3-5 feet in the latter portion of the period. Saturday: The pressure gradient will tighten between the sub- tropical ridge and an upstream cold front through the day. That along with a boost from the sea breeze will push winds close to advisory levels in Charleston Harbor and on the Charleston County Atlantic waters during the late morning and afternoon. On average winds will be SW at 15 or 20 kt, with gusts as high as 25 kt or so, especially over AMZ330 and AMZ350. Seas will hold around 3 to 5 feet, and highest on the Charleston County ocean waters. Mariners should remain alert for isolated to scattered t-storms moving in late in the day and during the evening hours. Saturday night: The cold front will move through the marine area early at night, clearing the local waters by 06Z. This is followed by a weak post-frontal trough from the north late at night over the South Carolina zones. Winds will shift from SW early on to the W and NW behind the cold front, then clock further around to the NW and N with the trailing trough. Any lingering 25 kt gusts in the evening will come to an end, and winds and seas will stay below advisory thresholds thereafter. Sunday through Wednesday night: High pressure will dominate conditions as it builds in from the north early in the week, and eventually slide into the ocean and gradually further offshore with time. No advisory conditions appear to occur through the entire forecast period. Rip Currents: Although there is some question as to how much swell energy will reach the beaches, given that it is a holiday weekend and to better "mesh" with WFOs ILM and JAX, we opted for a Moderate Risk of Rip Currents at all beaches Saturday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 8 AM EDT Saturday for AMZ350. && $$ NEAR TERM...BSH SHORT TERM...33 LONG TERM...33 AVIATION...BSH/33 MARINE...BSH/33
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
709 PM CDT Fri May 28 2021 .UPDATE.../SVR 221/ Replaces 218 and 220 and valid through 07Z. && .AVIATION.../00Z TAFS/ Strong to severe storm complex moving through AUS at 00Z issuance time. With strong winds associated with this segment of storms, the chance for improving conditions will happen faster that at the other 3 TAF sites. SAT/SSF/DRT will probably see a couple rounds of convective cells with shifty and unpredictable wind directions possible through 06Z in San Antonio and through 08Z at DRT. AUS probably has the higher potential for a severe wind speed however. Mostly VFR skies should follow, but guidances call for some intermittent MVFR or even some IFR cigs with residual shower activity. Will stick with the more stable and fair solutions and adjust later if necessary. && .PREV DISCUSSION... /ISSUED 431 PM CDT Fri May 28 2021/ UPDATE.../ADDED LLANO TO WATCH #218/ A new severe watch may be in the plans for later this evening, but severe storms are grazing the northern border of Llano County. Watch 218 was expanded to buy some time until 00z for Llano. PREV DISCUSSION... /ISSUED 308 PM CDT Fri May 28 2021/ SHORT TERM (Tonight through Saturday Night)... Storms firing along an front/outflow boundary over Central TX will likely threaten Burnet/Williamson/Lee counties by aroun 20Z. Moisture rich environment as the storms move south should make for a slightly more skinny CAPE profile over time and lead to heavy rain and damaging winds and 1 inch hail as the elevated threats as the storms expand south into the metro cities in the evening hours. A new weather watch may be needed for western counties shortly (per MCD #786), and this will be over an area where >2 inch hail threats are higher, with cooler and drier air aloft west of a line from Burnet to Boerne to Crystal City. The dry-line is pretty far to the west, so the first storm cells that enter this delayed threat area may also me coming from the front/outflow boundary to the north. Colliding cells and the high pwat levels near 2 inches will congeal the storms into an MCS with a solid line expected by the time San Antonio is impacted. Judging by the last few runs of the HRRR the severe and heavy rain threat may ease up over AUS as early as 9 pm. However, the coarser scale models do less with outflows and show more late night activity through the I-35 corridor rooted toward an amplifying mid level trough. Where the developing frontal boundary is by midnight should help determine whether the threat continues in to the early morning hours. At this time would guess the severe threat could last into around 09Z over the Rio Grande Plains. Most of the models depict a shortwave mid level ridge over Texas to combine with the overworked low level airmass. Thus low chance PoPs over eastern counties and little to no rain is expected over western counties for most of daytime hours Saturday into Saturday night. LONG TERM (Sunday through Friday)... Sunday should be the driest day of the forecast, but still will carry low chances for some afternoon convection. Another shortwave to move through the area from the southwest leading to storm development over the higher terrain in Mexico, then moving east into the Rio Grande Plains Sunday night. Continued disturbances Monday, along with a cold front positioned to our north will enhance rain chances Monday into Tuesday. By mid to late week, a deepening long- wave trough that extends through the Plains into Mexico will fire off more shortwaves through the area into the end of the week. This extended wet pattern could lead to isolated areas of flash flooding, as there has been little time to recover from the past rain events. Temperatures will be mild and slightly below normal, though the humidity will make it feel warmer. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 68 83 69 82 68 / 70 40 10 30 - Austin Bergstrom Intl Airport 67 83 68 82 68 / 70 40 - 20 - New Braunfels Muni Airport 70 85 69 84 69 / 80 30 - 20 - Burnet Muni Airport 67 82 66 81 67 / 70 40 - 20 10 Del Rio Intl Airport 71 89 74 88 73 / 60 10 20 30 40 Georgetown Muni Airport 67 82 67 81 67 / 70 40 10 20 10 Hondo Muni Airport 69 87 70 86 70 / 80 20 - 10 10 San Marcos Muni Airport 68 84 68 83 68 / 70 30 - 20 - La Grange - Fayette Regional 71 84 69 84 69 / 70 50 10 20 0 San Antonio Intl Airport 69 85 69 84 70 / 80 30 - 20 10 Stinson Muni Airport 71 87 71 86 71 / 80 30 - 20 - && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Oaks Long-Term...KCW Decision Support...33
Area Forecast Discussion
National Weather Service Gray ME
939 PM EDT Fri May 28 2021 .SYNOPSIS... Low pressure will pass south of the region tonight bringing rain to southern and central areas. Rain will taper off on Saturday but conditions will remain cool and cloudy. Another low pressure system will move up the Atlantic coast on Sunday and Sunday night with rain overspreading the region again. Showers are expected to slowly give way to improving conditions on Memorial Day with quiet weather and moderating temperatures through midweek. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 940 PM Update...Adjusted PoPs just a tad for the next few hours based on the progress of the northern edge. Tightened the PoP gradient up a little bit. Otherwise, no significant changes to the going forecast. 625 PM Update...Very little change to the going forecast other than to lower temperatures a bit where it`s raining. It`s 49 degrees in Keene NH, with some readings around the 44 degree mark at higher elevations in the Monadnocks. Otherwise, PoP timing looks really good going forward. Previously... High Impact Weather Potential: * Frost possible along the Canadian border. * Locally heavy rain far southern NH tonight. Pattern: Early afternoon water vapor imagery shows a shortwave trough building into the Great Lakes Region...with a moisture plume east of this feature originating in the Gulf of Mexico and arcing north and east into New England. Another...more subtle shortwave is located over southeastern Ontario...moving south and east along the southern flank of much larger scale troughing centered over Labrador Drilling down to the surface...there is a weak area of low pressure taking shape east of the Great Lakes trough over the Ohio Valley with a precipitation shield to it/s north and east in a region of frontogenetical forcing. The movement of this low and it/s attendant precipitation shield will be the primary forecast concern through this feature pushes towards ridging that is centered over James Bay...but is supplying Canadian air from the north. Through this Evening: Clouds will continue to stream in from the west with rain slowly edging eastward, but struggling as it encounters 20-25F dewpoint depressions over southern NH. Rain through 8pm will be light...and confined to the lakes region and points south in NH. From MHT-ASH east there may only be a few sprinkles by this point. 8pm temperatures will be in the 40s in the mountains...and low 50s to the south. Tonight: Low pressure pushes east along baroclinic zone stalled south of New England overnight. As it does so...impressive band of mid level frontogenesis strengthens below right entrance region to a 150kt jet streak at H2 with an easterly low level jet strengthening to 30-40kt north of the stationary front. PWATs above 1.5" will be available south of the boundary. The setup suggests good low/upper level coupling of forcing for ascent with this combination of variables yielding a band of moderate to locally heavy rain over southern NH and far southern ME. The northern edge of the rain shield should be sharp with dry Canadian air still poised to the north. Some uncertainty remains with this as the 28.12Z NAM has shifted northward along with the EC/GFS...but with recent HRRR runs as well as the CMC global and regional a bit further south. Have edged PoPs northward just a bit with the majority of any rainfall remaining along/south of a LEB-IZG-LEW- RKD line. Rainfall amounts will increase as you head south with overnight values nearing 1" along the MA border. This could cause some localized ponding of water...but no significant flooding is expected. At the other edge of the forecast area...some breaks in the clouds and very low dewpoints will allow for another round of chilly overnight lows. Stayed above the MOS guidance which was far too warm in many locations last night...with mid/upper 30s over our northern tier of zones. Areal coverage of temps in the lower 30s is very small /right along the international border/ and therefore have held off from any frost/freeze headlines. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... High Impact Weather Potential: Minimal. Saturday: Wave of low pressure south of Cape Cod will push north and east to a position south of Halifax by Saturday evening as mid level shortwave shifts east. Precipitation shield will slowly erode from northwest to southeast as this occurs. While somewhat drier low level air will slowly push in from the north through the day...the mid level cloud deck looks to hold tough for all but far northern areas. Low level northeasterly trajectories portend a chilly day and the raw 2M temperatures in the guidance agree well on this point. With showers continuing through some of the morning over southern areas...and deeper moisture remaining entrenched here...expect the coolest highs...with values struggling to reach 50. These values will challenge record low high temperatures for the date /45 at KCON in 1917 and 49 at PWM in 2017/. Further north where skies will be a bit brighter...mid/upper 50s are expected. Saturday Night: Northeasterly flow continues as high pressure remains centered just north of Maine with another area of low pressure taking shape off the Mid Atlantic coast as upstream shortwave begins to close off as it nears the coast. As the flow aloft begins to back...deep moisture will start lifting north once again with cloudy skies likely to dominate the period. Isentropic ascent over the warm front to our south may bring showers into our far southern zones before daybreak. As for temperatures...the deepening cloudiness will result in a rather small diurnal range...with temperatures along the coast into the foothills only falling into the lower 40s...with upper 30s in the mountains. Finally...with a strengthening gradient...northeasterly winds will freshen overnight...particularly along the coast with 10-20mph winds continuing through the overnight. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Overview...The second half of the Memorial Day weekend looks wet, at least late Sunday into Sunday night, but showers/rain will linger into Monday morning as well. Conditions dry out Tuesday and Wednesday before a rather large storm system over the Great Lakes may bring chances for showers to the region for the latter half of the week. Cool temperatures will gradually warm over the first half of the week and peak around mid-week. Impacts...While the overall impacts from rainfall late Sunday into Monday morning will not be meteorologically significant (i.e., no flooding expected, etc.), will note the unfortunate timing related to the holiday weekend. Forecast Details...The focus of the long term will be on the first two days of the period, Sunday and Memorial Day, as low pressure looks poised to move up the New England coast late Sunday into Monday. A period of beneficial rain for southern areas looks likely, centered on Sunday afternoon into Sunday night. Sunday begins with a closed upper-level low centered over the eastern Great Lakes and the Ohio Valley with weak waves of low pressure present along a quasi-stationary front off the East Coast. One of those weak waves becomes enhanced with aid from the upper low late Sunday, strengthening some as it slowly moves up the New England coast through Monday evening. An area of rainfall will begin to move into southern areas late Sunday morning as the low develops, gradually spreading northward through the evening and eventually covering the entire CWA. The rain continues Sunday night and into Monday morning before coming to an end sometime Monday afternoon as the low begins to accelerate north. As far as amounts...the 00Z GFS and Euro ensemble QPF data show that the mean rainfall totals for Sunday through Monday morning for Manchester and Portland are around an inch. However, Portland`s mean lies above its 50th percentile in the Euro ensemble while Manchester`s lies below its 50th percentile. Overall, both ensemble and deterministic guidance suggests that western ME looks to have the best chance for the highest rainfall totals. This forecast may ultimately be a bit light compared to the latest guidance, but it is higher than the previous forecast with room to trend in either direction as we get closer to the event. Will also note that the latest deterministic Euro is much slower than the latest GFS with this system, potentially pushing rainfall into fair to say that there is still some overall uncertainty with this portion of the forecast. In the wake of that system, high pressure builds to our south, eventually centering off the East Coast by Wednesday. This will allow a broad southwesterly flow to develop over the Northeast through mid-week. While temperatures on Sunday will continue to be on the cool side, the southwesterly flow will allow a warming trend to begin Monday and continue through mid-week. Other than a few showers in northern areas Tuesday afternoon, we should remain dry on Tuesday and Wednesday. Toward the latter half of the week, a large baroclinic zone stretching into New England ahead of a large system over the Great Lakes may bring some chances for showers to the region on Thursday. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Short Term... Summary: Low pressure passing south of the region tonight will bring rain to much of the area....with conditions gradually improving Saturday afternoon through Saturday night. Restrictions: VFR all sites at the moment. Rain arrives over southern NH this evening...spreading north and east overnight. Within the rain shield...conditions will deteriorate to MVFR/IFR. VFR conditions will hold at HIE...with uncertainty whether rain reaches AUG/RKD. Rain diminishes Saturday morning with improvement to VFR Saturday afternoon and evening. VFR will dominate much of Saturday night...but towards daybreak Sunday rain may bring restrictions back to southern terminals. Winds: Light winds /turning onshore along the coast/ will gradually shift northeasterly tonight and increase to 12g18kts for the day on Saturday. Northeast winds continue 5-15kts Saturday night. Lightning: No lightning is expected through Saturday night. LLWS: No LLWS is expected through Saturday night. Long Term...Rain begins to overspread the region from the south late Sunday morning, bringing associated MVFR/IFR restrictions to all terminals by late Sunday afternoon. Rain continues through Sunday night before ending late Monday morning through early Monday afternoon. Breezy northeast winds on Sunday will become lighter and more northwesterly through Wednesday as high pressure builds into the region. && .MARINE... Short Term...Northeasterly winds strengthen over the waters late tonight with SCAs likely for Saturday and continuing through Saturday night. Long Term...SCA likely ongoing for the outer waters Sunday morning, and while winds should diminish beginning Sunday afternoon, seas are expected to remain above 5 ft through Sunday night and possibly into Monday morning. Rain is likely over all zones Sunday and Sunday night and likely early Monday morning. High pressure builds south of the waters late Monday, bringing lighter winds and lower seas for Tuesday and Wednesday. && .TIDES/COASTAL FLOODING... Astronomical tides remain high through this weekend. While surge values will increase slightly as low pressure passes south of the region...tide heights are gradually decreasing and therefore no significant coastal flood impacts are expected. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory from 8 AM to 6 PM EDT Saturday for ANZ153. Small Craft Advisory from 4 AM Saturday to 4 PM EDT Sunday for ANZ150-152-154. && $$ NEAR TERM...Arnott/Ekster SHORT TERM...Arnott LONG TERM...Watson
Area Forecast Discussion
National Weather Service Lake Charles LA
1033 PM CDT Fri May 28 2021 .DISCUSSION... Wx map shows weak sfc high pressure ridge over East Texas/Louisiana this evening. Satellite and area radar imagery shows a Mesoscale Convective Complex (MCS) centered just west of Houston. Earlier short term guidance didn`t have as good a handle on this system, but the latest HRRR guidance finally picked up the feature. The result is more or less the same, with slow weakening as it moves southeast, but additional development with the remnant outflow boundaries possible across Southeast Texas/Southwest Louisiana and adjacent coastal waters. For the most part, mainly adjusted the evening chances of precipitation, with little adjustments overnight. For the remainder of the forecast, no major changes made. DML && .PREV DISCUSSION... /issued 644 PM CDT Fri May 28 2021/ DISCUSSION... 00Z 29MAY21 TAFs AVIATION... VFR conditions will prevail through tonight with possible MVFR CIGS and VIS as a boundary reaches SETX and extreme western SWLA. Isolated thunderstorms could develop along and ahead of this boundary. Otherwise, tomorrow we can expect northerly / northeasterly winds and mid to high level clouds. Stigger/87 PREV DISCUSSION... /issued 420 PM CDT Fri May 28 2021/ SHORT TERM [Tonight through Saturday Night]... A potentially active short term period is expected, though there is not a great deal of confidence in the details this afternoon. Frontal boundary to the north is progged to sink south through the forecast area overnight, while clusters of showers and thunderstorms initiating over central/eastern TX track generally TWD the SE. Model guidance is a bit all over the place, but generally agree that the current convective activity may glance SE TX this evening, with the greater chance of rain coming overnight into SAT morning as a shortwave trof approaching from the west initiates new convection. Highest chances reside across SE TX into far SW LA through the day, with rains expected to come to an end during the evening as drier air filters in and the shortwave departs to the east. Seasonal low temperatures are expected tonight, with highs tomorrow moderated by clouds/convection and post-frontal CAA. Below normal lows are expected Saturday night, with upper 50s across parts of central LA and lower 60s along the I-10 corridor. 13 LONG TERM [Sunday through Friday]... The front that passes early during the weekend will stall over the northern Gulf of Mexico and then start to move northward back into our area Monday into Tuesday. This may lead to the formation of showers and thunderstorms during these days. The front will weaken and eventually dissipate sometime on Tuesday or Wednesday. SREF shows a light amount of rainfall accumulation Monday evening. However, GFS and WPC keep all accumulation along the western periphery of our area until late on Tuesday. This forecast adds a small amount of accumulation compared to WPC for Monday and Tuesday. Severe weather will not be expected early in the week. An additional frontal system will begin to make its way into our area from the northwest on Tuesday. The broad cyclonic (counter- clockwise) flow from the system will help to funnel moisture northward from the Gulf of Mexico. It appears that the low pressure center over Oklahoma will intensify Wednesday into Thursday, strengthening the northward flow and leading to high chances for precipitation. The GFS, ECMWF, and WPC agree on accumulations of rainfall Wednesday evening into Thursday. A risk of severe weather cannot be ruled out for the middle of the week (Wednesday and Thursday). The additional frontal system will be expected to stall and weaken northwest of our area. It will then be expected to dissipate Thursday evening into Friday. Rainfall chances will continue through Friday. 55 MARINE... High pressure will persist over the northeastern Gulf of Mexico through tonight, with mostly light southerly winds persisting. Winds will increase and shift to northeasterly during the weekend as a weak frontal system drifts into the Gulf of Mexico. Light onshore flow will return for early next week as the front lifts back northward and washes out. 13 && .PRELIMINARY POINT TEMPS/POPS... AEX 67 79 59 81 / 20 30 0 0 LCH 72 82 63 83 / 30 50 10 10 LFT 70 82 62 82 / 20 30 10 10 BPT 70 83 64 83 / 40 60 10 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Midland/Odessa TX
632 PM CDT Fri May 28 2021 .DISCUSSION... && .AVIATION... Have ongoing storms along the Pecos River moving into the Permian Basin with additional storms moving down from Ern NM. Carrying TSRA at INK... PEQ... and MAF. More storms expected overnight... could see local MVFR cigs and vsbys with storms. && PREV DISCUSSION... /issued 202 PM CDT Fri May 28 2021/ DISCUSSION... KMAF 18Z RAOB shows a cap still in place, but considerably less than the 12Z run. For some reason, the raob came in w/a sfc Td of 24C, yielding mucapes of over 7000 J/kg! After editing the sounding for a sfc Td of 19C, mucapes dropped to 3400 J/kg, which is still potent. Mid-lvl lapse rates of near 9C/km and a wet-bulb zero of 8600` call for very large hail, and dcapes of 1300 J/kg suggest damaging winds as well. Deep-lyr shear of 40 kts will help maintain supercells, as will a 35+kt LLJ this evening. Radar already shows the first cell going up nrn Brewster County, and this is in line w/the latest HRRR run, which develops additional convection Permian Basin late this afternoon, then SE NM this evening on a possible MCS moving SE out of NM. Saturday looks to be a little less active, w/the primary focus being orographic lifting on easterly flow to the higher terrain out west near the dryline. By Sunday afternoon, the west coast trough will be over Baja del Norte, sending a strong shortwave into West texas and Southeast New Mexico, w/Sunday night looking to be best chances for rain this forecast, w/a continued severe threat. Monday night looks wet/severe as well, as another shortwave calves off the trough. Chances drop off after Monday, but the trough remains parked over Baja, and moisture isn`t going anywhere, so a chance of convection remains in play each day. It goes w/out saying that temps will remain below normal in this pattern, given expected convection/cloud cover each day. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 63 81 67 79 / 50 30 20 30 Carlsbad 64 87 67 85 / 20 20 30 50 Dryden 67 87 70 84 / 40 10 30 30 Fort Stockton 64 87 68 84 / 30 20 20 30 Guadalupe Pass 60 85 62 82 / 10 30 40 40 Hobbs 61 82 65 79 / 40 20 30 50 Marfa 58 89 62 84 / 10 30 30 40 Midland Intl Airport 63 82 67 80 / 50 20 20 40 Odessa 63 84 67 81 / 50 20 20 40 Wink 65 88 68 86 / 40 20 20 40 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$
Area Forecast Discussion
National Weather Service New York NY
936 PM EDT Fri May 28 2021 .SYNOPSIS... Unsettled weather is in store for the weekend, as waves of low pressure move along a stationary front south of the area. One last low pressure tracks near the coast Sunday into Monday, followed by high pressure briefly returning on Tuesday. A slow moving frontal system may impact the region mid to late next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Temperatures have cooled fairly significantly as widespread rain, locally moderate at times, overspreads the region. The rain will continue for the majority of the night as surface low pressure over the Ohio Valley redevelop off the Middle Atlantic coast tonight. This is in response to an upper trough over the shifting towards the Ohio Valley tonight. In addition, strong southeast/easterly flow will increase overnight as the surface low approaches. With decent low level/850mb flow, moisture will continue to advect into the region, with PW values nearing 1.5-1.75" per model soundings. Models have been pretty consistent in advertising a period of heavier precipitation overnight before tapering off early Saturday morning. HREF continues to show a widespread 1-2" rainfall in across the area in the 6 hr prob. matched means, with highest amounts across eastern LI and southern CT. Some of the heavier precip may be associated with remnant convection that is currently near the DC metro. The HRRR has been continuing to signal this activity lifting northward as the secondary low redevelops off the Middle Atlantic. This convection should pass just south of Long Island, but some heavier bands could move across portions of Long Island and southeast Connecticut around or just after midnight. A rumble of thunder cannot be ruled out here, but have left mention out of the forecast since the airmass still appears too stable. Rainfall amounts by 12z Saturday should average around 1.5 to 2 inches across the area. Minor flooding is the main threat as the rain falls in a relatively long duration. Have also increased winds a bit overnight. Forecast soundings are indicating a well mixed boundary layer up to just below 4 kft. Winds at the top of the mixed layer average around 40 to 45 kt after midnight. Do not think this intensity will mix to the ground, but gusts 30 to around 35 kt are looking likely along the immediate coast. Winds further inland should be weaker, but could still see some gusts 25-30 kt. Temperatures should fall into middle and upper 40s overnight. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... Uncertainty in the forecast with respect to precipitation through Sunday. Light precipitation should continue into Saturday morning, and begin to taper off for a period by afternoon, as the surface low departs off to the east. The aforementioned upper trough cuts off by Saturday night, and slowly meanders northeast through the Great Lakes, becoming positively tilted by Sunday afternoon, keeping the area in deep cyclonic flow. Under gusty northeast/easterly flow and cloud cover, temperatures will remain nearly steady through the day, struggling to get out of the 50s. Shaved a few degrees off the NBM deterministic for temperatures on Saturday as they`re near the median. With spread from the upper 40s to upper 50s in the inter-quartile range, this may still be a bit high, should temperatures tonight cool to the wet bulb, especially northwest of NYC, and have trouble recovering Saturday. Winds diminish Saturday night as the low heads away from the area. Another weak low pressure develops off DelMarVa by late Saturday, with an inverted trough feature hanging to our south. This will keep the area in extensive cloud cover Saturday through Sunday evening, with precipitation chances increasing again by Saturday night as the surface low approaches from the south. Guidance differs a bit on the evolution of the track of this weak low, which will impact our sensible weather. The NAM, CMC and EU have a more westerly track up the coast through NYC, while the GFS is further east off the coast of Montauk by early Monday. In fact, the EU is the slowest of the guidance, keeping the low near the area into late Monday. Have not bought off on this scenario just yet, but worth watching in subsequent cycles. Nonetheless, precip chances remain in the forecast Sunday into Monday morning, with the bulk of the precipitation likely Sunday afternoon into Sunday night, with another 0.25 to 0.5" possible across the region. The surface low exits the area Monday morning as the flow aloft becomes zonal and the upper low shears out to the northeast. After another day of easterly flow and cool temperatures on Sunday, but a moderating trend under northwest flow begins Monday, with highs back up in the low 70s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... High briefly returns on Tuesday to keep us dry, then an approaching warm front brings a chance of an afternoon shower on Wednesday or Wednesday night. There is some question as to the timing of this front with the faster GFS lifting it across area on Wednesday while the ECMWF lifts it across the area Wednesday night into Thursday. Once the warm front lifts to the north, the region will lie between western Atlantic high pressure and yet another longwave trough and associated low pressure and cold front to our west. The trends are indicating both Atlantic and Gulf of Mexico moisture transport will get involved. The axis of the deepest moisture along with the timing and strength of both the longwave trough and western Atlantic ridge will ultimately play a role in determining the days with the highest probability of rain. For now, have capped PoPs at high chance for the end of the week owing to the uncertainty. High temperatures Tuesday through the end of the week are expected to be near to slightly above normal. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... Low pressure will pass to the south tonight and then to the east on Saturday and bring rain with gusty winds. The rain will be heavy at times tonight as the low makes its closest approach, then become lighter daytime Saturday as it pulls away. It remains uncertain how strong winds may become overnight as the low approaches. Some guidance is forecasting peak sustained winds over 25 kt with gusts up to 40 kt, but think may be too high and have gone with a more conservative 20-25G35kt. Flight cat should lower to IFR in heavy rain tonight, then gradually improve to MVFR in most places for daytime Saturday. Cigs will likely be slower to improve E of the NYC metros. Winds at FL020 should increase to 40-45 kt along the south shore of Long Island, impacting mainly KISP and also KLGA/KJFK/KBDR/KGON to a lesser extent, from about 06Z-12Z. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... AMD possible to fine-tune winds and flight cat. .OUTLOOK FOR 00Z SUNDAY THROUGH TUESDAY... .Saturday night...MVFR conds should lower to IFR late as rain with another wave of low pressure starts to arrive. NE winds G25kt along the coast. .Sunday and Sunday night...Rain with IFR conds. NE winds 15G20-25kt, diminishing throughout and possibly shifting to SE-S along the coast as low pressure tracks overhead or nearby/ .Monday...Lingering rain with MVFR to IFR possible. Improvement and more dry conditions forecast for late day into Monday night. .Tuesday...VFR. .Wednesday...Possible MVFR with a chance of rain showers. Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ && .MARINE... Gale conditions across all waters, except for NY Harbor and the western LI Sound, where SCA gusts are probable, tonight through Saturday morning as a surface low approaches. Ocean seas will build tonight into Saturday, mainly 6-9ft through Saturday morning. Gale conditions are likely across the western LI sound and NY Harbor for a period on Saturday morning as well. As such, a Gale Warning was issued for these areas for Saturday morning, with gusts to 35kts likely. Winds will diminish somewhat by Saturday night, but will remain in SCA range with seas 4-6ft into early Monday across all ocean waters. SCA conditions should subside by Monday afternoon. Conditions on all waters will be below advisory criteria Tuesday into Wednesday with a weak pressure gradient in place. && .HYDROLOGY... One to 2.25 inches of rainfall is likely tonight into Saturday, resulting in some nuisance flooding in low lying and poor drainage areas. Additional rainfall is possible mid to late next week, but amounts are uncertain at this time. && .TIDES/COASTAL FLOODING... Widespread minor coastal flooding is likely with tonight`s high tide. This is due to increasing E-NE flow and only about 3/4 to 1 1/2 ft surge needed to reach minor benchmarks. A coastal flood advisory remains in effect for the south shore back bays, lower NY Harbor, and Western Long Island Sound. Locally moderate flooding cannot be ruled out, specifically across the most vulnerable locations along the south shore back bays. Impacts should be minimal with just isolated minor flooding across the upper NY Harbor and a coastal flood statement remains here. A coastal flood statement also remains for southwest Suffolk for mainly along the western portion of the Great South Bay where isolated minor coastal flooding is possible. While astronomical tides are lower with the late morning/early afternoon high tide on Saturday, isolated minor coastal impacts are possible along the vulnerable locations along the south shore back bays. Residual from the expected rainfall could also keep tide levels higher. Saturday night`s high tide should also bring more widespread minor flooding impacts across the south shore back bays due to persistent NE flow. The coastal flood advisory for the south shore back bays has been extended through Saturday night. A new coastal flood advisory has also been issued for Saturday night`s high tide along the lower NY harbor and portions of the Western Sound along the SW CT and southern Westchester shoreline. Elsewhere, tide levels should remain below minor benchmarks. If water levels end up a bit higher, then additional statements and/or advisories may be needed for Saturday night across the Western Long Island Sound across NW Long Island and possibly along the Great South Bay and upper Harbor. Easterly swells will likely result in a sweep of 4 to 6 ft surf tonight into Saturday, causing some minor beach erosion issues. Dune impacts look localized and limited to minor. There is a high risk of rip currents at Atlantic Ocean Beaches through Sunday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Coastal Flood Advisory until 4 AM EDT Saturday for CTZ009-010. Coastal Flood Advisory from 1 AM to 5 AM EDT Sunday for CTZ009. NY...Coastal Flood Advisory until 1 AM EDT Saturday for NYZ074. Coastal Flood Advisory from 10 PM Saturday to 2 AM EDT Sunday for NYZ074. Coastal Flood Advisory until 4 AM EDT Saturday for NYZ071-073- 078-176-177. Coastal Flood Advisory from 1 AM to 5 AM EDT Sunday for NYZ071. High Rip Current Risk through Sunday evening for NYZ075-080- 081-178-179. Coastal Flood Advisory until 2 AM EDT Sunday for NYZ075-178- 179. NJ...Coastal Flood Advisory until 1 AM EDT Saturday for NJZ006-106- 108. Coastal Flood Advisory from 10 PM Saturday to 2 AM EDT Sunday for NJZ006-106-108. MARINE...Gale Warning until noon EDT Saturday for ANZ331-332-340-345. Small Craft Advisory until 6 AM EDT Saturday for ANZ335-338. Gale Warning from 6 AM to noon EDT Saturday for ANZ335-338. Gale Warning until 6 PM EDT Saturday for ANZ350-353-355. && $$ SYNOPSIS...DBR/DS NEAR TERM...DBR/DS SHORT TERM...DBR LONG TERM...DS AVIATION...BG MARINE...DBR/DS HYDROLOGY...DBR/DS TIDES/COASTAL FLOODING...DS
Area Forecast Discussion
National Weather Service Phoenix AZ
250 PM MST Fri May 28 2021 .UPDATE...Updated Fire Weather Discussion. && .SYNOPSIS... Seasonable dry and warm conditions under clear to mostly clear skies are expected across the lower deserts through at least early next week. High temperatures will mostly top out in a 99-102 degree range through the holiday weekend with readings likely a bit warmer for the middle of next week. A slight increase in moisture mostly across eastern Arizona for next week may be enough for some isolated mainly high terrain thunderstorms by early next week and into the weekend. In addition, an isolated shower or thunderstorm can not be entirely ruled out for the Phoenix area deserts for much of next week. && .DISCUSSION... Yesterday marked the 7th consecutive day of mostly below normal, or equal to normal, high temperatures for Phoenix with a high of 99 degrees. That trend should end today as with an above normal high of 102 degrees forecast for Phoenix, which would be 3 degrees above the normal high of 99. The early afternoon upper level RAP mesoscale analysis indicates a dry westerly H5 flow aloft on the SW flank of a ridge to the east. There was also a weak, dry UL trough and associated weak PVA anomaly crossing the area with the main trough pushing into central Canada. Clear to mostly clear skies were also noted across our region with a large ridge positioned over the NE PAC. Mid- level WV imagery also showed a swath of slightly elevated moisture entering the region through SE CA. A warming trend will continue today with highs topping out in Phoenix and the lower deserts in the 99-102 degree range. Models then agree on dry southwesterly flow with flattened ridging into tomorrow with a weak mostly-dry positively tilted low pressure system dropping from southern CA to over the N GOC-NW MX just SW of the region from Saturday into Monday. As as result expect highs in a fairly narrow range through the period. Highs will climb to near 100-102 degrees for Saturday with the weak low allowing for a very slight dip in temps with highs near 99-101 for Sunday and Memorial Day Monday. The Clusters forecast analysis shows the strong W US ridge now actually peaking in strength on Wednesday and beginning to shift east and weakening on Thursday and Friday. There are also hints of weak troughing lingering to the southwest on Friday. For QPF chances for Wednesday through Friday the Clusters show at least one minor cluster favoring very minor QPF each day which would be associated with very isolated showers or high-based thunderstorms. Better shower and storm chances would be favored across the higher terrain areas north and east of Globe as well as SE-NE AZ. However the much more likely and bullish solution favored by the Clusters is dry conditions associated with the strong midweek high pressure building in from the northwest and associated mid-week warm up to near 102-104 degrees on Wednesday and Thursday. Still, on the GEFS plume PW moisture gradually increases from near 0.6 Monday to around 0.8 late in the week associated with the weak troughing thats possibly lingering to the South or southwest. The end result are very low-end POPs for Phoenix for much of the week and into next weekend. The latest indications are that the midweek warm-up resulting in areas of moderate heat risk could possibly be reigned in by increasing moisture and decreasing high pressure during Thu and Fri which would mitigate an excessive heat event as temperatures settle back to near 100-102 late this week and into the weekend. However, out west the late week temperature could be a few degrees warmer at around 103 to 105 degrees. && .AVIATION...Updated at 1808Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: No significant impacts to aviation through the TAF package. Winds will favor normal diurnal trends with a switch to west- southwesterly across the valley between 19-21Z. Speeds will be generally light this afternoon, however, can`t rule out a few thermal gusts reaching into the 14-18kt range, especially KPHX & KDVT. A return to easterly flow during the overnight hours before the typical switchback to westerly tomorrow afternoon. SKC to start, transitioning to a FEW250 deck around sunset and eventually going SCT250 by early morning. Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns anticipated through the TAF period. Wind directions will follow typical diurnal trends. At KIPL, expecting a few hours of southerly winds with gusts to 15kts before subsiding around 04Z. KBLH will see slightly higher gusts to 20kts out of the south for several hours between 21-02Z before tapering off for the overnight period. Skies will start off generally clear, but a FEW deck AOA 250 will move ohd by later this afternoon before becoming SCT250 overnight. && .FIRE WEATHER... Monday through Friday: Weak upper level troughing will settle in over the region Sunday into Monday with high pressure increasing by Wed, however max temps will remain slightly above normal through the entire period. A gradual increase in moisture during the period is likely to bring some isolated thunderstorms across the AZ high terrain, with lower desert storms not entirely out of the question though much less likely. However, wetting rains are not very likely, so these isolated storms may pose a dry lightning threat. Min RH values will remain quite low, mostly staying between 5-10% each day. Daily max RHs will mostly range from 20-30% with higher readings across the western deserts. Winds will remain fairly light through the bulk of the period, but with typical afternoon breeziness most days. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Sawtelle AVIATION...D`Anthony/Feldkircher FIRE WEATHER...Sawtelle/Kuhlman
Area Forecast Discussion
National Weather Service Pueblo CO
310 PM MDT Fri May 28 2021 .SHORT TERM...(This evening through Saturday) Issued at 305 PM MDT Fri May 28 2021 Currently...satellite imagery and radar show isolated thunderstorms developing off the southern Sangre de Cristo range, east into the Raton Mesa this afternoon. Satellite imagery also shows robust cumulus fields over the Mountains, and into the Pikes Peak region. A few weak radar returns are showing up near Pikes Peak. Temperatures have warmed nicely, with 70s to mid 80s across the region. Winds are southeasterly across the Plains, which has help keep moisture pooled up there. Dewpoints are currently running in the upper 40s to lower 50s. Rest of today...thunderstorms are expected to remain confined to near the New Mexico border this afternoon. CAPE values are rather high across this area, at around 1500 j/kg. Shear is weak and westerly. The potential exists for storms to become near severe off the Raton Mesa over Las Animas County. Hail could briefly approach one inch in diameter and wind gusts near 60 mph are possible with stronger storms. Elsewhere, storms are expected to remain sub-severe at this time, with gusty outflow wind to near 50 mph, especially over the Pikes Peak region. Tonight...thunderstorms along the New Mexico border should dissipate and track southeastward this evening with the loss of day time heating. Up north, any cells that develop will also quickly dissipate this evening. Dry conditions are expected overnight. At the surface, lee cyclogenesis is forecast to strengthen across the Plains, which will draw deeper moisture northward across the Plains. Dewpoints are forecast to remain in the 50s with southeasterly flow level flow. This will help keep temperatures mild, with lows in the mid to upper 50s. The san Luis Valley is expected to fall into the upper 30s to lower 40s. Saturday...severe weather is looking likely across the Plains. Upper level shortwave ridging is forecast to shift across Colorado and into western Kansas through the afternoon. A strong embedded upper disturbance will also shift east under the ridge by the afternoon. At the surface, the lee cyclone is forecast to strengthen and shift northeastward throughout the day. Currently, there is a bit of uncertainty as to where the cyclone will set up; a few CAM solutions have the low near Pueblo, while a fe have it up near Limon. Currently prefer the more southerly solutions given the majority of high-res guidance follows this, as well as the coarser resolution models. Low level southerly flow will continue to pull moisture northward across the Plains. Dewpoints are forecast to remain steady or rise slightly into the upper 50s across the far Eastern Plains by afternoon. MLCAPE values are forecast to rise in excess of 1500 j/kg by early afternoon. 0-6 km shear is also forecast to strengthen to near 35 kts by early afternoon. With the more southerly surface low track, low level winds should draw more easterly along and north of Highway 50. Expect thunderstorms to develop from the Palmer Divide, southeast toward Baca County by mid afternoon. Given the parameters, large hail, to 2 inches in diameter, strong winds in excess of 60 mph and locally heavy rainfall will also be possible. Areas along and north of Highway 50s, from Pueblo, southeast towards Springfield, will have the best wind profiles for rotating updrafts. Given the east to southeast surface winds, this area may also see the greatest potential for a tornado or two during the afternoon. Mozley .LONG TERM...(Saturday night through Friday) Issued at 305 PM MDT Fri May 28 2021 ...Scattered strong to severe thunderstorms possible throughout the late hours of the evening over the eastern plains. Large hail of up to 2" in diameter, along with strong and gusty winds of 70 mph or greater, and even a few isolated tornadoes are possible with some of these storms. There will still be a slight chance of severe thunderstorms for Saturday night as well... Saturday evening through Sunday morning... The region will be under a ridge with troughing beginning to take shape upstream over California, which will help to advect moisture in the mid to upper levels from the southwest over Colorado. Meanwhile downstream, a low located to the northeast over southern Canada and a trough to the southeast over the deep south will result in splitting and diffluence aloft over the area, and therefore the atmosphere will become primed for possible strong to severe thunderstorm development later in the day and into the evening, especially over the eastern plains, once the capping deteriorates. CAPE values will be the highest right around 00Z over the counties of Bent and western Kiowa, with some models showing values of most unstable CAPE close to 4000 J/kg and LI values of -8, therefore there could potentially be severe thunderstorms over these locations. Helicity values do appear to be very low so the biggest threat would be large hail and strong winds accompanying these storms, although with some models displaying high bulk shear values of 60 to 70 kts, and the NAM12 producing high SIG TOR parameter values of around 2, so a few isolated tornadoes cannot be ruled out. Most likely area for these to occur would be over the eastern plains and up to the Kansas border up until around 03Z on Sunday. Soundings do indicate that there is a pretty good inverted V with skinny CAPE, so the potential also exists that there could be some very strong downdrafts and microbursts could become a hazard as well. The HRRR is picking up on a possible MCV developing over Las Animas around 00Z, and then producing a very strong outflow of possibly greater than 60 kts (69 mph), which could be affecting the counties of Baca, Bent, and Otero to the north. Some strong storms could also develop over the Sangre de Cristo and Wet Mountains, as well as the Rampart Range earlier in the afternoon around 19Z, and these could become severe as well as they move out over the plains along the I-25 corridor. Most of the stronger to severe thunderstorms should begin to weaken after around 9pm as the environment begins to stabilize more with the absence of surface heating, however, the risk of thunderstorms will continue throughout the night with enough diffluence aloft still in place and cyclogenesis taking place over southeastern Colorado. Skies will remain mostly cloudy overnight. Winds will generally be light and variable for most locations, although with they will begin to increase during the evening over the eastern plains and become strong and gusty out of the south, then shifting more SE and weakening by early Sunday morning. High temperatures on Saturday will be fairly mild for most locations until clouds increase, and then fall to right around the seasonal average for perhaps slightly above with such an extensive cloud cover over much of the CWA. Sunday afternoon through Monday night... As the cyclogenesis continues with the low propagating a little further south over NE New Mexico, it will begin to usher in more moisture that will be wrapped around on the backside of the deformation zone, right over much of the plains and overrunning occuring as far west as the San Juan Mountains, therefore it looks to be very possible that most of the CWA will experience periods of rainshowers with embedded thunderstorms throughout much of the day on Sunday, especially later in the afternoon and evening hours. Lower levels will become more saturated with higher dewpoints extending westward up to the I-25 corridor, with a dryline setting up to the south and east and the forcing could allow for a better chance of thunderstorms along this boundary as well. Most of the instability will have shifted back to the western CWA and there could potentially be some strong to severe thunderstorms over the central mountains later in the afternoon as forcing and lapse rates appear to be more favorable in these areas. Main threat for this reason will be flooding over the burn scars potentially, especially if some of these storms become stationary. On Monday, the very positively tilted axis in the long wave trough over the southwestern US is going to cause the low to become cutoff south of California, which will help to keep the surface low remaining in place over New Mexico into Monday, and this will allow for a very similar setup for more continuous showers and thunderstorms possible over much of the CWA. There will be cooler temperatures advected in from the north over the plains, so this, along with extensive could coverage, will keep max temperatures well below the seasonal average, by as much as 25 degrees in some locations. This cooler air at the surface could also help to enhance overrunning, yet the lower levels will also be much more stable and therefore most of the showery precipitation will be on the light side, and continue throughout the night. Also, with snow levels dropping on Monday as colder air moves in, peaks above 10,500 feet could get anywhere from a dusting to a few inches of new snowfall. Lows for Monday night will be cooler as well, and slightly below the seasonal average for most locations, from the 40s over the plains, to the upper 20s and 30s for high country. Tuesday through Wednesday... The surface low will begin to exit the region by early Tuesday morning and allow for clearing to finally take place for most locations throughout the morning. Afternoon thunderstorms will develop later in the day over the mountains with some residual moisture and the long wave trough axis still overhead. The U/L cutoff low over the southwest will eventually detach itself from the trough and allow it to begin to fill and shift further eastward on Wednesday, although with a jet maxima upstream over the Dakotas, and a sharply positive tilted axis, this will still put southeastern Colorado in the divergent quadrant, so thunderstorms look to develop over the mountains during the afternoon. The ECMWF is showing that there could also be some convection over the far eastern plains in the evening as a dryline sets ups from the trough right along the Colorado/Kansas border, although the GFS keeps the boundary much further south with a quicker propagation time of the trough moving southeastward. So depending on which model holds true, will determine if the far eastern plains possibly get strong to severe thunderstorms later in the evening on Wednesday. Thursday through Friday... The deterministic models and ensembles are in fair good agreement that a ridge will begin to build back in over the region with much warmer temperatures returning, back to the seasonal average or even slightly above for many locations. Due to there being enough instability for the U/L cutoff low remaining off the coast of southern California and feeding up a substantial amount of mid level moisture from the south over the region due to this, there will still exist the chance of afternoon and evening thunderstorm development. Most of these storms will be confined to the mountainous areas of the CWA, but some could develop over the plains as well, especially on Thursday. Steward && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 305 PM MDT Fri May 28 2021 KALS...VFR conditions through the next 24 hours. A few thunderstorms will remain possible over southern portions of the San Luis Valley this afternoon, but confidence in one hitting the terminal is low. Another round of afternoon thunderstorms is possible Saturday. isolated thunderstorm will remain possible through this evening at the terminal. Southeasterly winds are expected into this evening, becoming northerly overnight. More widespread thunderstorms are forecast for Saturday afternoon, with reduced VIS and CIGS expected. KPUB...VFR conditions through Saturday morning. Winds are forecast to be southeasterly this afternoon, and turn northerly overnight. Widespread thunderstorms are forecast for Saturday with reduced VIS and CIGS expected. Mozley && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...MOZLEY LONG TERM...STEWARD AVIATION...MOZLEY