Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/23/17

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
748 PM CDT Mon May 22 2017 .DISCUSSION...Have made some minor changes to the POPs for tonight and have scaled back on the coverage as showers appear to be rapidly dwindling. Meanwhile, kept at least some mention of showers and storms tonight as the stalled frontal boundary meanders across the Rio Grande Plains and for possible convective activity over the Mexican Plateau that could drift east into western portions tonight. The best chances will be possible over the coastal waters as they are more convectively unstable overnight. && .PREV DISCUSSION... /issued 659 PM CDT Mon May 22 2017/ DISCUSSION...Updated for latest aviation discussion below. AVIATION...A stalled front and a variety of convective outflow boundaries are currently in place across the Mid to Lower RGV with some shower activity near KMFE. This activity should pass through quickly with an otherwise mostly rain-free evening expected. Models do indicate some isolated showers overnight as weak impulses moves through the mean flow and interact with the nearly stationary front. However, confidence on placement or timing remains too low to mention in the TAFS. Meanwhile, low MVFR clouds will likely form again overnight as predominately SE winds allows moisture to increase. For Tuesday, there is some indication for showers or storms as the stalled front meanders across the area during the morning and afternoon time frame. However, by the late afternoon or early evening, a cold front will move south through the region with more widespread showers and thunderstorms expected...with some storms possibly becoming severe. PREV DISCUSSION... /issued 229 PM CDT Mon May 22 2017/ SHORT TERM (Tonight through Tuesday Night): A stalled front resides over the CWA, with a radar signature pushing slowly across Willacy, Hidalgo, and Cameron Counties. But despite continued rich low level moisture and available buoyancy, ongoing isolated to scattered convection should weaken tonight. The HRRR prolongs convection out west over the Sierra Madre range into tonight, so can`t rule out a few storms moving into the Zapata and Starr sector. Overnight low temperatures will be propped up in the 70s by high dew points, with low clouds moving in on light southeast marine winds. Winds will be light to moderate Tuesday, and possibly northeast on the backside of washing out frontal boundary. Another front will push south from the southern Plains during the day, edging through Tuesday afternoon and Tuesday night, with convection increasing in coverage as the front overtakes the residual stationary front and interacts with a ready supply of rich low level moisture, supported to some extent by destabilizing energy aloft. The GFS shows a vort max moving off the Mexican mountains in the evening which could help prolong convection and support stronger cells moving toward the coast. The forecast sounding for Cameron County Tuesday afternoon boasts a PW of 1.90 inches, historically above the 90th percentile for the day. The lapse rate will be a healthy 8 deg C per km. CAPE will be 3700 J/kg with a supercell parameter of 9.0, and a SHiP of 1.9, supportive of supercells and significant hail. The probability of severe convection Tuesday to Tuesday night in conjunction with this event is currently rated at slight, or 15%, by SPC, focusing on the threat of large hail and damaging wind/wind gusts. Brief heavy downpours will be possible in any stronger storms. The arrival of cooler, drier air along with the lingering rainfall potential should put the kibosh on convection later Tuesday night, and also allow low temps to dip into the 60s for the northwest 2/3 of the CWA. LONG TERM (Wednesday through Monday): Surface high pressure will continue to bring drier air into the Rio Grande valley and northern ranchlands Wednesday as northwest flow aloft provides subsidence across the state as the 500mb trough across the central United States moves eastward. 500mb ridge across the southern and central Plains Thursday will continue to provide subsidence across south Texas even as an onshore flow returns at the surface. A somewhat zonal flow develops across the southern tier of the country Friday before an upper level trough develops across western U.S. Saturday and moves eastward across west TX Sunday. This will allow moisture to increase across portions of north-central TX through the weekend and convection is progged to develop across north TX late Sunday and move southward Monday as a weak cold front moves southward across the state. This will provide a chance of showers and thunderstorms for the upper portions of the Rio Grande valley late Monday. MARINE (Now through Tuesday night): Light to moderate southeast to south winds tonight and Tuesday, shifting to moderate north late Tuesday night in the wake of a cold front. Low to moderate seas. Scattered showers and thunderstorms, some strong to severe late Tuesday. Wednesday through Saturday...Moderate north to northeast winds will prevail across the coastal waters Wednesday before high pressure across the lower Texas coast moves eastward Wed night. Winds will veer to the southeast Wed night and increase Thursday as the pressure gradient increases across the western Gulf of Mexico with low pressure across the TX panhandle and high pressure across the northern Gulf. Moderate to strong southeast winds will prevail across the lower TX coast Thursday through Saturday. SCEC to borderline SCA conditions will prevail across portions of the coastal waters Thursday through Saturday. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 69/58
Area Forecast Discussion
National Weather Service Green Bay WI
1020 PM CDT Mon May 22 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Tuesday Issued at 226 PM CDT Mon May 22 2017 The latest rap analysis and satellite/radar imagery show upper level low pressure centered across Lake Superior, a compact shortwave moving east over South Dakota, and a surface trough positioned over southern MN into Nebraska. Scattered showers will continue to move east from northwest WI into north-central and far NE WI for the rest of the afternoon. Instability has been slow to build over central and east-central WI so far today, but continue to see cu build up in this area, and hi-res mesomodels continue to point towards some showers developing. Any thunderstorms will most likely be isolated given the lack of forcing and instability. More widespread shower activity exists over SD with the compact vort max. As this shortwave moves towards the area late tonight into Tuesday, rain chances and trends will be the main forecast concerns. Tonight...Upper troughing will continue to reside across the northern Great Lakes, while the shortwave trough over eastern South Dakota moves into southwest Wisconsin late in the night. A few showers over far northern WI and also over east-central WI could linger into the mid-evening hours. Once the lingering showers diminish, should see a lull in the precip chances until the shortwave over SD and associated surface low move into southwest Wisconsin late. Did slow the chances down somewhat based on the latest model data. Low temps ranging from the upper 30s in the north to near 50 over the southern Fox Valley. Tuesday...The shortwave will swing northward across western Wisconsin, and will lay out a convergence zone just west of the Fox Valley and Bay of Green Bay. Though some showers will likely be moving northeast across central WI at the start of the morning, this convergent zone looks to be the focus for shower activity for the rest of the day. Do not see much instability with clouds and precip arriving in the morning, so left the mention of thunder out of the forecast. Temps will be cooler in many spots, and range from the upper 50s to low 60s across the region. .LONG TERM...Tuesday Night Through Monday Issued at 226 PM CDT Mon May 22 2017 Precipitation trends are the main forecast concern. An upper level trof and inverted surface trof will bring showers to the entire region Tuesday night, and to the southeast portion of the forecast area on Wednesday. A weak ridge of high pressure will bring dry conditions Wednesday night into Thursday evening, but small rain chances will return as WAA develops late Thursday night into Friday. A series of weak short-wave trofs and associated cold fronts will continue to bring periodic bouts of scattered showers thunderstorms through the Memorial Day weekend, but the majority of the period should be dry. Have sided more with ECMWF, as the GFS has been exhibiting signs of convective feedback issues with the weekend forecast over the last few days. Below normal temperatures at the beginning of the period will moderate to slightly above normal by Friday and Saturday, then back to normal for the end of the holiday weekend. && .AVIATION...for 06Z TAF Issuance Issued at 1020 PM CDT Mon May 22 2017 Isolated convection noted along a boundary extending over east central Wisconsin late this evening. This boundary extends to a low pressure system and upper disturbance over northeast iowa. Anticipate more isolated showers and storms along this boundary overnight with mainly vfr conditions. Shower activity may become more numerous over central and east central Wisconsin Tuesday along with MVFR/IFR cigs developing. Since the showers may be more scattered to isolated across northern Wisconsin, mainly MVFR cigs anticipated through Tuesday afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......TDH
Area Forecast Discussion
National Weather Service Jackson MS
1002 PM CDT Mon May 22 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION... As of 230z, a surface low was located near the MS/LA line just NE of Baton Rouge with an inverted trough axis extending into central MS and a baroclinic zone just inland separating a moist unstable marine layer from cooler more stable air to the north. Meanwhile aloft, broad troughing is located across the central US with a coupled jet structure supporting upper level divergence across the ArkLaMiss. Strong isentropic ascent above the baroclinic zone in concert with the aforementioned coupled jet helped to support an expansive area of moderate to heavy stratiform rain across a large portion of the CWA this afternoon and is still ongoing, but lower rainfall rates with this area of precip have precluded a greater flash flooding threat so far. Latest RAP analysis also indicated the presence of an internal diabatically enhanced potential vorticity anomaly which has helped to strengthen the low level flow and moisture advection into the area. For the remainder of the evening, the heaviest rainfall is starting to edge into the south central portions of the forecast area and will slowly spread further north and east overnight. This is where the flash flooding potential will be maximized mainly south of the I-20 corridor where 2 - 4 inches of additional rainfall with some locally higher amounts will be possible. As such, the current flash flood watch and limited/elevated areas in the HWO look well placed and will let ride as is for now. The majority of the lightning activity has been well offshore over the Gulf and with little instability not expecting any severe weather so the marginal risk was removed in accordance with the latest SPC outlook. However, an isolated lightning strike or two cannot be entirely ruled out as a few pockets of moist absolutely unstable layers move through the area. Last, but not least, a few areas of patchy fog are possible tonight mainly along the Hwy 84 corridor and portions of the Delta as the rain moves off to the east. /TW/ Prior discussion below: Rain has been slow to advance east today, but saturated lower levels now are ensuring much more reaching the ground. Surface low over southeast TX remains responsible for the widespread isentropic ascent and should continue tonight as the low moves along the baroclinic zone along the coast. Have some concern that the low may shift a bit to the north as better baroclinicity actually exits from west central LA into southwest MS. If this occurs, heavier rainfall could develop further north than expected right now. As of now, expect around 2 inches in the far south with locally higher amounts. Most of the heavy rainfall will depart into AL by 12Z Tuesday, but digging mid level trough and at least a few breaks in the cloud cover should be sufficient for scattered thunderstorms in the afternoon. The best lapse rates will occur in the east during the afternoon and with around 40 knots of deep layer shear, would not be surprised to see some isolated severe storms here./26/ Tuesday night through Sunday...our winds aloft will remain out of the southwest as a closed low drops south from the Upper to Mid- Mississippi River Valley by Wednesday morning. A shortwave rounding the base of the closed low will swing east across our CWA and help support a weak cold front and another good chance of showers and storms Tuesday night into Wednesday. Cooler and drier air will filter into the CWA in the wake of the cold front but the closed low will continue to drop southeast across northeast Mississippi and maintain light rain chances over the northeast half of our CWA during the day Wednesday. By Wednesday evening, dry weather is expected and the skies will clear from the southwest. With mostly clear skies and a drier airmass over the area, the coolest morning lows of the forecast period are expected Thursday. Most sites will bottom out in the lower 50s. Thursday and Friday will be dry with a warming trend. Low amplitude ridging aloft will move over our CWA while a surface high strengthens over the northwest Gulf and ridges back to the west across the Gulf coast states. The resulting southerly flow will slowly increase moisture back across our area. Saturday mid level ridging will strengthen over the Gulf and may limit convection across our southern zones but elsewhere deep enough moisture will be back across our CWA to combine with daytime heating to result in isolated to scattered afternoon and early evening storms. Models differ on timing but another closed low near the upper Plains and Canadian border will deepen a trough over the central CONUS Sunday into Monday. This will lead to increasing rain chances Sunday into Monday. /22/ && .AVIATION... 00Z TAF discussion: A mix of VFR to IFR ceilings are occurring this evening as a large swath of rain is ongoing over many TAF sites. This will continue to reduce vis and ceilings through the rest of the evening. Some heavier showers or storms could occur through the night. Overall, not good flying conditions through daybreak. Conditions should improve after 17Z Tuesday. /28/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 64 79 58 73 / 87 48 60 17 Meridian 64 80 60 74 / 91 81 58 32 Vicksburg 61 80 58 75 / 92 37 62 13 Hattiesburg 65 82 63 77 / 89 84 57 22 Natchez 62 79 58 74 / 85 34 62 10 Greenville 60 78 57 73 / 91 34 61 18 Greenwood 62 78 57 71 / 97 42 61 25 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...Flash Flood Watch until 7 AM CDT Tuesday for MSZ052-054>066- 072>074. LA...Flash Flood Watch until 7 AM CDT Tuesday for LAZ024-026. AR...None. && $$ TW/22/26/28
National Weather Service Jackson KY
1126 PM EDT Mon May 22 2017 .UPDATE... Issued at 1110 PM EDT MON MAY 22 2017 Hourly grids were freshened up based on recent observations, which led to no substantial changes at this time. UPDATE Issued at 835 PM EDT MON MAY 22 2017 The region remains under the influence of a broad trough that encompasses much of the Conus east of the Rockies. Within this trough, a shortwave was moving from the Lower MS Valley and into the Southeastern Conus. This shortwave is expected to track into the Southern Appalachians tonight and then northeast of the area during the day on Tuesday. This system is still expected to bring a threat of isolated to scattered rain showers late tonight and on Tuesday mainly across the southeast parts of the area. A thunderstorm cannot be ruled out on Tuesday as well. As for tonight and tomorrow, the inherited forecast looks on track with only slight adjustments to hourly temperatures and dewpoints. && .SHORT TERM...(This evening through Tuesday night) Issued at 430 PM EDT MON MAY 22 2017 19z sfc analysis shows high pressure in place over Kentucky, though it was not effective enough to keep the high clouds at bay. These, along with light north winds, have helped to keep temperatures contained in the 60s through the afternoon for most places. Readings did hit the low 70s in the far south but only mid to upper 60s, so far, elsewhere. Meanwhile dewpoints are running in the mid 40s to lower 50s. The models are in good agreement aloft through the short term portion of the forecast. They all depict a deep and broad trough over the mid section of the nation amplifying and dipping southeast into the mid Mississippi Valley during the next 36 to 48 hours. This will place eastern Kentucky in broad southwest flow with plenty of energy breaking free to ride over the JKL CWA from Tuesday afternoon into Wednesday. Toward the end of the period the GFS solution starts to separate from the ECMWF with the core of its trough digging a bit closer to Kentucky. Will favor a general blend through the period with a lean toward the higher resolution HRRR and NAM12 models through the first part. Sensible weather will feature a quiet night with some ridge to valley distinctions opening up after sunset but mitigating late in the night due to increasing clouds from the south. These clouds will be the vanguard of a sfc low moving into the southern Appalachians tomorrow with a few showers possibly sneaking past the border and into our CWA by dawn. The shower chances will continue in the far east Tuesday with a few thunderstorms possible by mid afternoon in these areas. A better chance of showers and storms then develops to our southwest - pushing in later Tuesday night - likely washing over the bulk of the CWA by sun-up Wednesday. Again used the CONSShort and ShortBlend as the grids` starting point with some adjustments to lows tonight owing to a ridge to valley split developing early but mixing out in the east late. As for PoPs, did tighten them up along our southern and eastern border late tonight into Tuesday. .LONG TERM...(Wednesday through Monday) Issued at 347 PM EDT MON MAY 22 2017 Models are in good agreement with mid and upper level features through DY5 Friday, then increasingly diverge in solutions from there. Amplified and somewhat progressive flow will dominate the pattern through the extended. Upper level low and associated deep long wave trough will track slowly across the eastern half of the CONUS through week`s end. Short wave ridging will then transit the region before a second upper level low or trough drops out of Canada and into the Midwest and/or Great Lakes region. Most of the differences showing up after DY5 center around the evolution and timing of the second main storm system. The 0Z ECMWF is fastest with this system and the 6Z GFS the slowest. The 0Z Canadian appears to split the difference. The 12Z Canadian is showing better run to run continuity than the 12Z GFS and even trends closer to the ECMWF. The GFS suggests some phasing of the Canadian low with energy moving out of the Pacific, causing a futher deepening and digging of the system across the plains and into the Great Lake, a much slower and stronger solution overall. As a result confidence is quite low for the last 48 hours of the period. With respect to sensible weather, unsettled weather with periods of showers and thunderstorms will tend to keep daily highs near to or below normal levels for this time of the year and overnight lows above normal. Good forcing coupled with some instability will probably bring the threat of some thunder to the area on Wednesday. In addition, lowering freezing levels may allow for some of the showers/storms to contain small hail/graupel at times. A short lived window of dry weather can be expected across eastern Kentucky Friday, as the aforementioned transient short wave ridge moves across the Ohio and Tennessee Valleys. The threat of rain returns to the area Friday night and lingers through the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 835 PM EDT MON MAY 22 2017 VFR conditions prevail as drier air and high pressure has spread into the region. However, a low pressure system and mid level disturbance moving across the Southeastern Conus will brush the area from the south later tonight into Tuesday. A few showers could affect the TAF sites late tonight or on Tuesday with perhaps even a thunderstorm on Tuesday afternoon. However, chances and confidence were too low to include at this point. LOZ, JKL, and SJS will stand the highest chances for any of this activity. Even so, only mid level ceilings are expected with this. Winds will be relatively light and variable averaging 10kt or less through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...RAY AVIATION...JP
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1058 PM CDT Mon May 22 2017 .SHORT TERM...(This evening through Tuesday) Issued at 335 PM CDT Mon May 22 2017 After a week of rainy weather, the air mass has dried out quite a bit today with mostly sunny skies over much of southern MN into West Central Wisconsin. However, two areas of incoming clouds and precip will affect the area. Mid clouds and some showers had already moved into southwest MN with associated short wave coming from the northwest. There might be some thunder in south central MN and have kept those in the grids. That area will slide across our southern counties tonight. The other area of clouds and light showers will drop southward later tonight and Tuesday as upper trough drops south. This will affect central into southwest MN, and eventually east central MN into Wisconsin later Tuesday morning and afternoon. The GFS is rather bullish with more rain and clouds then most models, but have kept the grids a little quieter than that. .LONG TERM...(Tuesday night through Monday) Issued at 335 PM CDT Mon May 22 2017 A much drier pattern will take hold from the middle of the week onward, with only two main chances of precipitation - one with a front Thursday night into Friday and the other Sunday into Monday. Cyclonic flow will finally be on the way out Tuesday evening. Clearing skies will follow for midweek although temperatures remain cool in the wake of the impressively deep trough heading toward the East Coast. Temperatures rebound back toward normal Thursday in advance of the front and Friday/Saturday in the wake of the front where temperatures aloft actually warm a bit. Poor lapse rates should limit the thunder threat Thursday night/Friday and the GFS appears to be a bit too aggressive with precip coverage. Continued with 30-40 PoPs. Confidence diminishes Memorial Day weekend with GFS maintaining a closed low over the central U.S. while the GEM/ECMWF are much farther northeast with the system over the Great Lakes and a ridge building eastward into the High Plains. Either way, temperatures will trend back below normal and odds of a weekend washout appear low. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1058 PM CDT Mon May 22 2017 At 11pm, we are finally starting to see spotty MVFR cigs in northern MN, though the LAMP and HRRR were both saying this should be a widespread IFR/MVFR field. As mentioned in 00z discussion, there was concern the LAMP was overdoing its cig forecast and certainly trends this evening support that, with forecast conditions slowly improving in the LAMP. Based on SREF probs, MVFR cigs are most likely west of MSP, so continued to only have prevailing MVFR cigs at AXN/STC/RWF. In addition have trends for these airports more optimistic than what LAMP has. For precip, it looks to be of the hit- and- miss, on- and- off through the day Tuesday. Given that expectation, have prolonged periods of VCSH at all terminals. KMSP...Confidence is increasing in main MVFR cloud mass remaining west of MSP this period. Based on HRRR and other CAMs, expect diurnally driven scattered showers to develop late Tuesday morning and persist through the rest of the daylight hours. /OUTLOOK FOR KMSP/ Wed...VFR. Wind NE 5-10 kts. Thu...VFR. Wind SE 5-10 kts. Fri...VFR. Chc MVFR/-SHRA. Wind SW 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...TDK LONG TERM...BORGHOFF AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
633 PM EDT Mon May 22 2017 .SHORT TERM...(This evening through Tuesday) Issued at 409 PM EDT MON MAY 22 2017 WV imagery and RAP analysis indicated a mid/upper level low over portions of nrn Ontario into the nrn Great Lakes with several weak shrtwvs rotating around this feature. At the surface, an elongated low and occluded front was located btwn Lake Superior and James bay. Vis loop, radar and obs showed abundant low clouds lingering across Upper Michigan along with some isolated showers or sprinkles through the cntrl and ern cwa. The -shra were had intensified slightly with the limited daytime heating. Tonight, any lingering instability showers should end early this evening with loss of diurnal heating. As the mid level low pivots and the stronger qvector conv shifts to the sw of the region, weak ridging will prevail over Upper Michigan with no pcpn. Expect enough lingering clouds to keep min temps from the upper 30s to the lower 40s. Tuesday, the stronger 700-300 mb qvector conv with the shrtwv digging into IA will continue to remain to the south of Upper Michigan. There may still be enough forcing and moisture ahead of the mid level trough axis along with some weak instability from daytime heating to support sct -shra over the srn cwa. Otherwise, temps will remain below normal with highs from the lower 50s near Lake Superior to thearound 60 south. .LONG TERM...(Tuesday night through Monday) Issued at 307 PM EDT MON MAY 22 2017 The main forecast highlights through the middle to end of the week will be a drying and warming trend, a few locations across the interior may see temperatures climb into the lower 70s by Friday! Rain chances look to return on Friday across the west, and pushing eastward into Saturday as a cold front pushes east across the area. There is some uncertainty as to whether or not instability will return this far north, so confidence in any thunderstorm activity is low right now. Towards the end of the weekend and beginning of next week, another system is progged to impact the region, bringing back better chances for precipitation. Patchy frost looks possible across the interior west early Thursday morning as a drier air mass moves in and skies clear giving way to ample diurnal cooling. Tuesday night, with lingering upper-level energy overhead, as the main trough axis slowly continues to push east across the area, expect light rains to linger across the central and eastern portions of the area. Wednesday, expect clouds to linger across the area before diminishing through the afternoon as high pressure begins to build southwest across much of the area. However, the exiting upper- level low is progged to linger just north of the Ohio River Valley and may overspread mid and upper-level clouds across the eastern half of the area. Wednesday night into Thursday, as the upper-level low begins to lift slightly, a few medium range models bring back precipitation chances across the far east as weak warm air advection tries to nudge back to the northwest. The Canadian is by far the most aggressive with this precipitation, which is likely in response to lingering shortwave activity being a bit more robust. During the day on Thursday, the upper-level low will continue to slowly lift east, but a few lingering wrap around showers may impacted far eastern portions of the area; therefore, have held onto the slight chance wording for rain showers through the day. However, across the rest of the area as weak upper-level ridging builds into the region, expect skies to be mostly sunny with ample insolation. This will allow for temperatures to modify back to near normal for this time of year. Friday through Friday night a weak cold front is progged to move east across the area, bringing back chances for rain showers. The upper-air pattern is rather complex during this time period, with longwave troughing extending south across the Northern Plains and transitioning to more zonal flow across the central and southern Plains. Given this split flow, confidence is not high that enough moisture will get this far north to support instability for thunderstorms. This is further supported by medium range models continuing to trend further south with the northern extent of MUCAPE. Depending on the speed of the front, precipitation may linger into Saturday. The Canadian is the slowest, with the front moving across Upper Michigan almost 12-18 hours after the GFS/ECMWF. Saturday may be a bit cooler in some locations depending on the speed of the cold front. Sunday into Monday, there is considerable uncertainty in how things will evolve. The longwave trough across the western CONUS is much stronger in the GFS and weaker within the Canadian, with the ECMWF falling in the middle; therefore, model solutions are a bit all over the place precipitation wise. However, given the lingering upper-level energy rotating about the region and the possibility for another shortwave digging south out of central Canada, expect temperatures to be on a slight downward trend through early next week with cloudy skies. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 633 PM EDT MON MAY 22 2017 MVFR conditions will develop again with cooling overnight and additional moisture advection. Winds will also be light enough to allow fog formation that may drop vsby to IFR for a short period Tuesday morning. SAW will go up to VFR with mixing during the day on Tue. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 409 PM EDT MON MAY 22 2017 A low pres trough lingering over the area will maintain fairly light winds across the lake through Tuesday. Winds under 20 kts should then be the rule into Fri as a relatively flat pres gradient dominates the Upper Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Ritzman AVIATION...07 MARINE...JLB
Area Forecast Discussion
National Weather Service Norman OK
738 PM CDT Mon May 22 2017 ...UPDATE... && .DISCUSSION... Made minor adjustment to precipitation probabilities, adjusting upward for much of central Oklahoma based on trends. 00z KOUN sounding revealed little instability and so ongoing strong/severe convection across southwest Oklahoma should weaken before impacting the I-35 corridor later this evening. Latest RAP sounding has 1,000-1,500 J/kg of MLCAPE across southwest Oklahoma and this is supporting a few intense cells with hail being the main concern. One anti-cyclonic mesocyclone that persisted across eastern Beckham County eastward toward Clinton produced golf ball size hail on the south side of Elk City. Per Bunkers shear vectors, left movers will most east-northeast at around 25 knots and right movers will move southeast at aruond 30 knots. Storm intensity and the severe threat should wane as storm intensity decreases later this evening. Otherwise only minor adjustments were made to other fields including wind. BRB && .PREV DISCUSSION... /issued 730 PM CDT Mon May 22 2017/ DISCUSSION... AVIATION... /For the 00z TAFs/ Latest regional radar mosaic shows showers moving across much of central and northern Oklahoma impacting PNC/OKC/OUN, but moving away from GAG/WWR. In the short term, the TAF sites with greatest concern are CSM and HBR. Thunderstorms may impact these sites through 02-03z and could even approach LAW. Once showers move east of the area by late evening, VFR conditions are expected. We`ll need to monitor ceilings later tonight through tomorrow morning as some locations could briefly see MVFR conditions but confidence was too low for inclusion at this time. BRB PREV DISCUSSION... /issued 314 PM CDT Mon May 22 2017/ DISCUSSION... The main concerns are rain/storm chances/potential tonight into Tuesday. Ongoing isolated to numerous light showers across central and northern Oklahoma as of 3 pm should weaken in the next several hours as isentropic lift around 700 mb weakens. This activity will remain rather light. Some thunder may occur with this activity, but do not think any strong or severe storms will occur due to limited instability (MUCAPE mainly below 600 J/kg). Severe thunderstorm potential now through tonight still appears to be low with decreasing confidence. Cloud cover and rain have limited instability in most locations north of a Mangum to Seminole line. South of this line, some sun and daytime heating have allow temperatures to rise into 70s. A few thunderstorms may form near and this cloud shield line in the next several hours, though this remains doubtful due to sufficient capping. Higher chances for severe storms appear to occur over far eastern New Mexico into west Texas late this afternoon where the air is more unstable. This activity will continue to move east and southeast, which may glance western north Texas and far southwestern Oklahoma this evening if they can organize into a complex or two. If severe storms occur, some severe hail and wind reports, mainly on the lower end of severe spectrum (hail less than golf ball size and winds under 70 mph), would be possible. No severe storms are expected north of the line mentioned above due to limited instability. After midnight tonight into Tuesday morning, a cold front will move south and through the area. A few lingering weak showers and thunderstorms may occur across the area. Tuesday afternoon, some clearing can be expected, though temperatures will remain on the cool side for late May. Sufficient daytime heating may allow for isolated to scattered showers and weak thunderstorms to form in rather chilly unstable airmass. If storms occur, no severe storms would be expected due to limited instability (less than 500 J/kg), however small hail up to nickels and gusty winds up to 50 mph could result. Tuesday night through Thursday, dry weather is expected. Thursday will be warmer (possibly much warmer) than Wednesday. Friday through Memorial Day, a warm/hot humid airmass may evolve across the southern Plains Friday through early Sunday, along for some potential for severe thunderstorms/heavy rainfall. Most models have been consistently depicting rather high amounts of potential instability (MUCAPE 2000-5000 J/kg), high low level moisture (surface dewpoints in the 60s to lower 70s), and sufficient shear (0-6 km bulk shear 30-50 kt) for severe storms with heavy rain late Friday through early Sunday. Capping may be strong and limit storm development. For now, kept low chances for storms across the area Friday night into Sunday. Have low confidence in severe storm and heavy rainfall potential during this time frame. Slightly cooler and drier conditions may occur with the passage of a weak cold front Sunday into Memorial Day. MBS && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 71 55 70 48 / 60 60 20 10 Hobart OK 70 53 70 47 / 80 60 20 0 Wichita Falls TX 73 59 72 51 / 30 50 40 0 Gage OK 66 50 68 43 / 60 30 20 10 Ponca City OK 73 53 69 47 / 40 60 20 10 Durant OK 75 58 70 51 / 20 40 40 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ 12/14
Area Forecast Discussion
National Weather Service Blacksburg VA
1149 PM EDT Mon May 22 2017 .SYNOPSIS... A cold front from Pennsylvania to northern Georgia will move southeast and stall across North Carolina by Tuesday as high pressure wedges down the Appalachians. Yet another area of low pressure will arrive midweek with added rainfall likely for Wednesday and Thursday. Friday will be the drier day this week. && .NEAR TERM /THROUGH TUESDAY/... As of 1132 PM EDT Monday... Watching slow moving moderate to heavy showers in the NC foothills/piedmont, along a weak convergence zone leftover by the front. Models indicate that isolated to scattered coverage will be the way to go over the next few hours per moisture convergence off the high-res models. Appears best rainfall will say just south of our CWA but looking for some increase northward overnight as low level flow turns to the southeast. The latest RAP indicates better deep moisture convergence pooling toward the NC foothills after 06z, but only briefly. Looks like rain showers will spread northeast along the Blue Ridge through morning, while other are surges northeast to the southside of VA. At the moment QPF seems low enough to not have any watches at this time. Better threat arrives more toward dawn. Will be watching slow moving cells for any local advisories. Previous discussion from early evening... Enough of an instability gradient over the NC foothills/piedmont to keep isolated to scattered convection around this evening. The high-res (HRRR/RAP) favor showers/a few thunderstorms from the NC/VA border in the foothills through southside VA through this evening, then should be weakening somewhat, transitioning to a more rain. Previous discussion from this afternoon... Water vapor loop showed a well defined short wave over Arkansas early this afternoon. Models track this feature into southern Virginia overnight. Surface and 850MB front cross the area this afternoon, but with little change in air mass behind it. 850MB winds back to the southeast by midnight brining the deep moisture north along the Blue Ridge and foothills. Best convergence will be from 12-18Z/8AM-2PM Tuesday. GFS may have some convective feedback and may be moving the wave too fast and too far northeast compared to other guidance. Some decent isentropic lift on the 3km NAM Tuesday morning. Leaned toward NAM and WPC for QPF .WIll have to monitor amounts since some locations have had lots of rain in the past 72 hours and have saturated soils as a result. Surface front reaches central North Carolina as high pressure moves from West Virginia into Pennsylvania. By Tuesday morning the in-situ wedge will be in place down the Appalachians aided by precipitation on the cool side of the front. Clouds and precipitation will keep temperatures down on Tuesday. Trending toward cooler guidance for maximum temperatures. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 330 PM EDT Monday... Large upper trof will be traversing the eastern US, keeping us in a wet pattern through the period. Multiple waves along the front to our east will be pulling away from the region Tuesday night. However, a low over the Ohio valley will be captured by the upper trof as it closes off and the stacked system will wrap up a cold front a push it into our area from the west Wednesday morning. There will be a bit of an in-situ wedge ahead of the front to limit instability and convective development, but good isentropic lift and dynamic support will make for widespread rainfall and some possibly some embedded thunder from lift over the stable layer. Also, there may be a very narrow window just ahead of the front where the wedge has weakened that may allow for deeper instability to support elevated convection in a highly sheared environment. While the overall probability of severe weather is low, the situation bears watching until fropa occurs early Wednesday night. Expect some lessening of showers overnight Wednesday night in muddy dry slot of stacked low spinning over the Ohio valley. Diurnal heating will pop showers and thunderstorms with steepening mid/upper lapse rates under the cold pool aloft as the upper trof swings through. Small hail/graupel in low topped convection look possible mainly west of the Blue Ridge. Showers/storms taper quickly with loss of heating in the evening, leaving some lingering upslope precipitation west of the Ridge into Friday morning. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 330 PM EDT Monday... Our unsettled pattern will continue through the weekend as a progressive upper ridge moves across the eastern US, followed by the development of another closed low moving through the upper midwest. This will allow a frontal boundary to sink into the region from the north and stall on Saturday, with a series of waves shearing off to our north dragging along weak, occluded fronts. While not likely a complete washout, we look to keep a good chance of showers and thunderstorms in the forecast through the weekend and into the first part of next week. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... As of 725 PM EDT Monday... Expect VFR this evening, the rain should start spreading northward overnight and cigs will start to sink to MVFR or lower, especially along/east of the Blue Ridge. The rain will become steadier and possibly heavier late tonight into Tuesday from BCB/ROA east. This pattern will stick around through the end of the taf period, but rain will be lighter over BLF/LWB. Extended Aviation Discussion... The chance of precipitation continues Wednesday and Thursday with sub-VFR conditions associated with any of the precipitation. Friday will be drier with a better chance of VFR ceilings and visibilities. Another front reaches the area for Saturday with more precipitation and sub-VFR conditions. && .HYDROLOGY... As of 345 PM EDT Monday... An inch to inch and a half of rain is expected tonight and Tuesday. Amounts will have to be monitored as some locations along the Virginia/North Carolina border, especially Carrol, Patrick and Henry Counties in Virginia and Stokes, Rockingham, and Caswell Counties in North Carolina. FFG along parts of the southern Blue Ridge was in the 1.5 to 2.5 inch range. More rainfall is expected Wednesday and Thursday, which could lead to small stream and river flooding. Models continue to favor areas along/east of the Blue Ridge, possibly resulting in another 1 to 3 inches of rain. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS/WP SHORT TERM...MBS LONG TERM...MBS AVIATION...AMS/JH/WP HYDROLOGY...AMS
Area Forecast Discussion
National Weather Service Shreveport LA
1015 PM CDT Mon May 22 2017 .DISCUSSION... Much of the -SHRA has shifted E of the region this evening with the departure of our shortwave trough...but mosaic radar imagery still depicts a weak low level circulation over SW LA N of LCH associated with a weak sfc low along a stalled frontal bndry extending from just offshore Sabine Pass NE to near LFT, into Srn MS N of MCB. This has resulted in some wrap-around -RA/-DZ over the Srn and Ern sections of Ncntrl LA, which should gradually shift E overnight as this sfc low lifts ENE across SE LA. Also seeing patchy -RA/-DZ farther W still lingering over portions of Deep E TX S of I-20 based on the low 02-03Z cigs/reduced vsbys, which also look to longer overnight as well. Farther NW...areas of sct slightly elevated convection continues to build SE towards the Red River of Srn OK/N TX, associated with a subtle shortwave that will eject ESE into SE OK/NE TX and into SW AR late. The short term progs suggest that this shortwave may dampen with time overnight as it approaches the region, and should also encounter slightly drier air especially as it enters SW AR. This convection should weaken in intensity as it approaches the region given the stability noted on the 00Z KSHV raob, but the advection of slightly steeper 700-500mb lapse rates warrants the continued mention of isolated thunder over NE TX/SE OK/SW AR/NW LA. Have updated the forecast to lower pops down to low chance across the SE sections of Ncntrl LA with the departure of the shortwave, and have also removed thunder mention as well. Did maintain low to mid chance pops late over NE TX/SE OK/SW AR/NW LA, with the progs not very bullish with the convection able to progress across these areas through daybreak. However, the latest run of the HRRR has changed significantly as of this time, and suggests the convection affecting more of these areas as well as all of SW AR. The HRRR also depicts additional convection over Wcntrl TX also pushing E and possibly affecting the SW sections of E TX prior to daybreak as well. A brief lull in the rain is expected Tuesday morning, but we will await the arrive of the upper trough now digging SSE into the lower TX Panhandle to trigger sct to numerous areas of convection over the region by afternoon. Did make a few minor (cooler) adjustments to forecast mins tonight as well, but otherwise, the current forecast still looks good. Zone update already out...grids will be available shortly. 15 && .PREV DISCUSSION... /issued 737 PM CDT Mon May 22 2017/ AVIATION... For the ArkLaTex, the last of the ra is edging East, but some DZ/BR/FG will all become likely with the setting of the sun. Overnight winds will be light and the ground saturation will wick into the air and keep all night. Slow improvement to occur with another fropa by this time tomorrow evening. Look for FG/BR/cigs to slowly lift by lunch and then shwrs/tstms to become likely as the cold front moves over the area. Climb winds are light and flight levels have a good W/SW jet 50-100KT from FL220-FL350. /24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 58 75 54 76 / 20 50 40 10 MLU 60 78 57 76 / 30 30 60 10 DEQ 56 73 49 74 / 30 60 20 10 TXK 56 73 52 75 / 20 50 30 10 ELD 56 74 52 74 / 20 50 40 10 TYR 59 73 54 78 / 20 60 20 10 GGG 58 74 54 77 / 20 60 30 10 LFK 62 79 58 81 / 20 60 40 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 15
Area Forecast Discussion
National Weather Service Tallahassee FL
920 PM EDT Mon May 22 2017 .NEAR TERM [Through Tonight]... The 7 pm surface analysis showed a quasi-stationary front from VA, through central AL, through coastal LA, and into south TX. The airmass ahead of this front was warm and very moist with PWAT values about 40% above climo for our region. All of the large scale models forecast weak Q-G forcing to persist overnight across our forecast area. This, combined with favorable thermodynamics, justifies keeping at least 20% PoPs. However, early Tuesday morning the HRRR generates a more widespread area of rain across the FL Panhandle and southeast AL as a perturbation associated with an MCS (currently over LA) reaches our region. This solution is supported, at least in part, by other CAMs. At this time we do not expect this rain to be particularly heavy. && .PREV DISCUSSION [743 PM EDT]... .SHORT TERM [Tuesday Through Wednesday Night]... A closed upper low north of the Great Lakes will open up as it lifts off to the northeast. Meanwhile, a shortwave over MN will drop southward with a low closing off over Iowa on Tuesday. This feature will continue southward into the Missouri Valley on Wednesday digging a deep trough along and east of the Rockies before beginning to move toward the east coast Wednesday night. A few upper level impulse accompanied by deep layer moisture along with a surface front stalling near the Gulf coast will bring a very wet pattern to our area through Wednesday. The first shortwave will arrive tonight and linger through Tuesday bringing with it widespread showers and thunderstorms. Along with the potential for heavy rainfall, SPC has our entire CWA highlighted for a marginal risk of severe thunderstorms. ECAM guidance shows the potential for MLCAPE as high as 1500-1800 J/KG Tuesday and forecast soundings show bulk shear values and an 85H jet of 30-40 kts. Additionally, PW`s will increase to around 2.0". The greatest severe threat will be damaging straight line winds but a tornado cannot be ruled out. There should be a short break in convection late Tuesday/early Wednesday before the next and more significant shortwave arrives ahead of the main upper trough. Expect another round of widespread showers/thunderstorms Wednesday with rain chances tapering off from west to east Wednesday night as the cold front pushes through the region. SPC has all but a portion of the SE Big Bend highlighted for a marginal risk with the SE Big Bend in the slight risk. Bulk shear and the low level jet are forecast to be in the 40-50 kt range but the limiting factor may be the lack of instability due to the earlier convective complex. As for the heavy rain threat, we will hold off on issuing a flash flood watch as latest QPF amounts have come down just a bit with the higher amounts (at or just above 3") shifted to our easternmost zones. These amounts are spread out through Wednesday night. .LONG TERM [Thursday Through Monday]... Much drier air will begin to arrive on Thursday in the wake of the cold front and remain in place through Saturday. Temperature and humidity levels will be below normal for late May through Thursday night with a gradual increase to seasonal levels by the weekend. Rain chances will return Sunday into the first part of next week with the approach of the next cold front. .AVIATION [Through 00Z Wednesday]... A few showers and isolated thunderstorms near TLH will gradually dissipate this evening and VFR conditions are expected across our area tonight under broken mid-high level clouds. Chances for showers and thunderstorms will increase across our area from west to east Tuesday morning, with periods of MVFR cigs and visibility likely at all terminals through the remainder of the day. Brief IFR/LIFR conditions cannot be ruled out in stronger thunderstorms, but VFR conditions are also possible during dry periods between showers/storms. .MARINE... Modest southwest winds will increase quickly on Tuesday to cautionary levels. A period of advisory levels winds and seas is expected late Tuesday through Wednesday night with the approach and passage of a strong cold front. Winds and seas will gradually diminish through the remainder of the work week as high pressure builds over the waters. .FIRE WEATHER... No concerns. .HYDROLOGY... Recent rains over the last 48 hours have deposited the heaviest amounts (3-4 inches) in the upper Choctawhatchee River Basin in Southeast Alabama. Elsewhere, rainfall amounts have been lighter generally 2 inches or less. Most of the guidance suggests that rainfall over the next 36 to 48 hours should generally be in the 3-4 inch range with isolated heavier totals up to 6 inches. While this could cause some minor flooding issues, slightly higher amounts would be needed to cause a greater flood threat. Thus, will not be issuing a flash flood watch on this cycle, though as confidence increases in the placement of Tuesday`s convection a watch may be needed. The threat for river flooding from this system remains quite low, given that many rivers were at significantly low levels from the ongoing drought. Only the Choctawhatchee River, which has received modest rains in the upper portion of the basin is vulnerable to minor flooding should heavier amounts on Tuesday materialize. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 69 81 68 80 60 / 30 70 70 70 20 Panama City 74 81 71 80 65 / 60 70 70 70 10 Dothan 69 78 67 80 59 / 70 90 70 70 10 Albany 71 78 67 79 60 / 50 80 70 70 10 Valdosta 70 81 67 79 61 / 30 70 70 80 30 Cross City 71 83 71 81 65 / 20 60 70 80 50 Apalachicola 74 80 72 82 65 / 30 60 70 70 10 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Fournier SHORT TERM...Barry LONG TERM...Barry AVIATION...Lahr MARINE...Barry FIRE WEATHER...Fournier HYDROLOGY...Godsey