Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/22/17

Area Forecast Discussion
National Weather Service Gaylord MI
1151 PM EDT Sat Oct 21 2017 .UPDATE... Issued at 1043 PM EDT Sat Oct 21 2017 Scattered high and mid level clouds continue to stream northeast across the area, well ahead of a slow moving cold front back across the Corn Belt. Not expecting too much change overnight, with a slowly thicken cloud deck as the front makes slow progress east. Moisture may become just deep enough across northern Lake Michigan and surrounding shoreline areas to kick off a few very light showers by sunrise. Otherwise, another unseasonably mild night, with overnight lows only dropping a few more degrees into the mid and upper 50s. && .NEAR TERM...(Tonight through Sunday) Issued at 333 PM EDT Sat Oct 21 2017 ...Summer`s last stand... High impact weather potential...elevated fire danger into early evening, as well as in ne lower MI Sunday afternoon. Deep southerly flow continues, well ahead of a cold front advancing across western MN/IA. Mid/high clouds continue in northern MI (with thinning in sw sections), but no cu, and surface dew points have again mixed out into the 30s in a few locales. Wx thru tonight will be mostly quiet, but showers will make a push into the region Sunday, along with the associated cold front. Any real low-level moisture is found pretty close to the incoming cold front. Even though surface dew points are climbing into the 50s in WI, the se half of the state has effectively no cloud cover. That isn`t stopping elevated showers from popping along a moisture gradient and vort ribbon aloft, from the STL area up to almost BEH. This axis of elevated convection increasingly fades to virga with northward extent. It`s going to difficult for this to generate precip this far north; Nam tries to spit out a few showers, toward and especially after 06z. Am not inclined to bite on this (the RAP is dry, at least for that part of the area). Pre-frontal moisture band does edge toward western sections very late tonight. The Rap is occasionally spitting our some showers ahead of the front, some of which impact the northern Lake MI islands, and western Mack Co. A slight chance for a shower might be justified here after 6am. Min temps tonight in the 50s to near 60f, coolest in the interior of ne lower MI, warmest along the Lake MI coast. Much better rain chances arrive Sunday from w to e, with the cold front across eastern upper and making inroads into nw lower MI during the afternoon/early evening. Height falls aloft are subtle, but present in the afternoon, especially in nw sections. The most widespread precip is likely to be along and just behind the boundary as it moves in. Chance pops warranted in nw lower and eastern upper MI thru early afternoon. Likely to categorical pops push as far east as Rogers/Mio/Gladwin by early evening, with only chance pops thru 00z/8 pm east of there. Rainfall amounts of a quarter-inch or so are expected in the west half of the forecast area. We might be able to muster 200-300j/kg of MuCape in northern lower MI. If coupled with stronger forcing, would be comfortable mentioning isolated thunder. But we don`t really have that, and will omit any thunder mention for now. Max temps Sunday mainly in the 70s (some upper 60s near Lake MI). Another day of elevated fire danger in ne lower MI, with warm temps and gusty winds ahead of incoming precip. However, RH levels will be higher than today. && .SHORT TERM...(Sunday night through Tuesday) Issued at 333 PM EDT Sat Oct 21 2017 ...The Gales of Late October... High Impact Weather Potential...Gusty winds winds on Tuesday and Tuesday night. Pattern Synopsis/Forecast...The cold front is part way through the forecast area at 00z/Mon and looks to take the next 12 hours to move through the rest of it. However, The ECMWF looks to slow down a bit, as the 500 mb trough digs in behind the front. Another piece of energy then digs into the 500 mb trough and begins to close off the trough into a closed low, on the ECMWF. The GFS is a little slower doing this overnight, so that by 12z/Tue the 500 mb closed low is somewhere over the Upper Great Lakes. The sfc low then deepens and moves to the N-NE, but at different speeds. This will affect the winds, as the ECMWF will be much windier behind the low than the GFS. We are looking at Gales over the Lakes either way, but the ECMWF could be showing gustier winds. Will wait on the next run or so to figure which way the models are going with this. Primary Forecast concerns...We can use a good soaker again, and while we will get a decent amount of rain, but think that it will be below the 2.5" in 6 hours that we would need for flooding. The other issue of concern, as alluded to in the previous section, is the forecast low track. If the ECMWF is right, it could end up quite windy with gusts to 40 mph so possibly some sort of wind headline. The GFS has moved the center of the low out, well north of the Upper Great Lakes, and the resultant gradient will support low end gales on the lakes, but probably not wind headlines on the land. So will have to watch the direction of the models. .LONG TERM...(Tuesday night through Saturday) Issued at 333 PM EDT Sat Oct 21 2017 ...Cooling off, but Continued at or Above Normal... Extended (Tuesday night through Saturday)...The pattern definitely looks to be flipping back to a fall like pattern with the usual strong wind storms that usually move through the Great Lakes this time of year. This also opens up the possibility of mixed precipitation, mainly at night and at interior, higher elevation locations, as we get close to the end of October. Tuesday night we start off in the midst of the first 500 mb closed low of days 4-7. It looks to try to lift out on Wednesday, only for a piece of energy to move into the back side of the low and retrograde it a bit before exiting and allowing the trough to lift out of the Upper Great Lakes by 12z/Thu. This will definitely cool us down and bring periods of rain through the Wednesday night. Expect a brief dry period for Thursday before the next bowling ball of cold air and rain moves into the region for Friday and Saturday. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1148 PM EDT Sat Oct 21 2017 VFR conditions through this morning will give to deteriorating conditions this afternoon and evening as a slow moving cold front moves into the region. Band of light to moderate showers will spread west to east very slowly across the taf sites later today and tonight, likely bringing some vis restrictions and IFR cigs along with them. Somewhat gusty south winds today will become northwest as the front passes. && .MARINE... Issued at 333 PM EDT Sat Oct 21 2017 Breezy southerly winds continue thru Sunday morning. A sharp cold front will slowly push into northern MI Sunday afternoon and night, with nw winds behind it. This front will also bring widespread showers beginning Sunday afternoon. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...SMALL CRAFT ADVISORY until 6 PM EDT Sunday for LMZ323-341-342- 344>346. LS...NONE. && $$ UPDATE...MB NEAR TERM...JZ SHORT TERM...JL LONG TERM...JL AVIATION...MB MARINE...JZ
Area Forecast Discussion
National Weather Service La Crosse WI
638 PM CDT Sat Oct 21 2017 .SHORT TERM...(This evening through Sunday) Issued at 230 PM CDT Sat Oct 21 2017 Water vapor satellite this afternoon shows the mean long wave trough has progressed through the Rockies. The trough and embedded short wave troughs will continue to work east through the night and then start to shear out Sunday as a closed upper level low looks to take shape across the lower Mississippi River Valley. This trough and embedded short wave troughs will provide the necessary lift for showers and storms along the cold front. Out ahead of the front, there is a strong cap in place above 800 mb and the 21.17Z RAP and 21.12Z NAM forecast soundings continue to show this cap will remain in place until the front arrives this evening. This will provide a very narrow window where there will be enough forcing and CAPE to support thunderstorms right along the front. Forecast soundings from the RAP show between 500 and 750 J/Kg of CAPE along the front in a tall, skinny profile with deep layer shear of 30 to 40 knots, most of which resides in the lowest 3 km. The main concern continues to be if this CAPE profile will be enough to balance out the shear and allow some stronger to potentially severe storms to form. If it does, strong to damaging winds continue to look to be the main threat and in that regards, no real change to current thinking or messaging. The storms should also be efficient rain producers with precipitable waters expected to be in the 1.5 to 1.75 inch range and warm cloud depths around 3.5 km. Expecting the front with the showers and storms to start moving into the western sections of the area right around 22.00Z and then move steadily east across the area through the night. The threat for strong to severe storms should diminish by late evening as the CAPE becomes minimal. Lingering showers behind the front Sunday morning, mainly over Wisconsin, will come to an end by early afternoon. The clouds will take a bit longer to clear but look for skies to become mostly sunny starting in the morning across the west and during the afternoon for the eastern sections. .LONG TERM...(Sunday night through Saturday) Issued at 230 PM CDT Sat Oct 21 2017 Much cooler weather still expected for this coming week. Overall, little change made to the previous forecast, although forecast confidence erodes heading through the middle and latter stages of the week. There will be one more mild/seasonable day Monday ahead of an upper trough that will dig southeastward towards the Great Lakes and drive a strong cold front through the area on Monday. Following the frontal passage, temps will fall below average on Tuesday with highs in the 40s to near 50. As the cold air aloft and steep low-level lapse rates interact with weak ripples within the upper trough, some showers are possible especially Monday night into Tuesday, with otherwise mostly cloudy, breezy and chilly conditions. Some differences exist Tuesday night into Wednesday with the 21.12Z GFS a little farther southwest with a reinforcing shortwave trough in northwest flow compared with the ECMWF, bringing light precip and increased clouds to the area. This could ultimately impact low temps and possible frost concerns Wednesday morning. Short-lived shortwave ridging is expected on Thursday with return southerly flow helping temps moderate to near or slightly above seasonal norms ahead of low pressure developing to the west. Beyond Thursday, confidence in forecast details remains lower, especially regarding any precip chances. Deterministic and ensemble guidance both support another upper trough moving into the central US late this week, a little farther west than the early week trough. A reinforcing surge of cooler, below average temps is expected for Friday/Saturday (850 mb temps falling to -6 to -9C by Saturday), with another chance for a widespread frost/freeze by late this week. However, run-to-run consistency among models has been poor during this time with the evolution of the upper trough, so stuck with model consensus pops late this week for now. It`s possible it could be cold enough for some snowflakes by late this week with any precip. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 638 PM CDT Sat Oct 21 2017 A cold front continues to approach the area, and will arrive at RST around 02Z and LSE by 06Z. Ahead of that front, a relatively brief period of showers and thunderstorms is expected, with temporary MVFR conditions possible along with potentially some brief gusty winds to around 25 knots. Behind the front, RST should dry out fairly quickly by around midnight at the latest, but additional showers are expected to develop near and east of the Mississippi River, impacting LSE through sunrise if not a little later. Also behind the front, ceilings will gradually rise into Sunday, with skies expected to clear entirely for RST by early afternoon while thicker cirrus hangs on around LSE. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...04 LONG TERM...JM AVIATION...Lawrence
Area Forecast Discussion
National Weather Service Caribou ME
921 PM EDT Sat Oct 21 2017 .SYNOPSIS... High pressure will build over the area tonight then move east of the region Sunday into Monday. A trough of low pressure will approach from the west on Tuesday. && .NEAR TERM /THROUGH SUNDAY/... 9:21 PM Update...High clouds are spilling over an upper ridge that is building to the west of the region. The high clouds are not having a big impact on temps as the northwest valleys have quickly dropped to around the freezing mark. It is still a relatively mild 55F at Bangor as of 9 PM. The main update was to the temperatures to reflect the temperature trend so far this evening, and the expected conditions the remainder of the night. Previous discussion... A chilly night upcoming and milder for Sunday. High pres expected to slide e overnight into Sunday. This will lead to some waa to start kicking overnight w/a return flow around the high. We tend to see some cold temps w/a setup such as this one setting up tonight. Decided to undercut the overnight temps by a few degrees w/some northern and western areas seeing the upper 20s. It looks like a decent inversion will set up later tonight as shown by the RAP and NAM12 soundings. There will be quite a variation in temps as low lying areas as far s as the downeast region will see temps in the 30s. Clouds are expected to move in later tonight w/most of thicker cloud cover across the southern 1/2 of the CWA. Most of the cloudiness with be cirrus around 25,000 feet. For Sunday, the clouds will lift to the ene by the afternoon as the upper ridge moves across the region. This will allow for more sunshine and w/a light ese flow, temps should rise well into the 50s and 60s across the region. Areas close to the coast will be cooler w/the onshore flow. Fire Danger is a concern for Sunday. See the Fire Weather section below. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... High pressure moving to the east combined with strong upper level ridging will bring a mild night Sunday night followed by a sunny and warm day on Monday. A southerly breeze will increase on Monday behind departing high pressure. Monday night will be unseasonably warm as the circulation behind departing high pressure continues. Some low clouds may begin to stray in Downeast areas late at night as low level moisture increases. The southerly wind will increase on Tuesday in the increasing gradient between high pressure off to the east and a trough of low pressure approaching from the west. Low clouds will spread across the area as moisture continues to increase and some patchy mist or drizzle is possible, especially Downeast. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A digging trough of low pressure approaching form the Midwest will be pushing up against a strong ridge of high pressure to our east Tuesday night into Wednesday. A corridor of deep subtropical moisture will be channeled north our way Tuesday night into Wednesday bringing bands of showers, some possibly heavy, as the trough pushes east into our area. A wave of low pressure will likely form off the Mid-Atlantic coast on Wednesday, then channel north from there as very strong ridging well to our east holds the frontal boundary over our region. This will bring the potential for some bands of potentially heavy rain across the area later Wednesday into early Thursday. The moist frontal boundary should lift northeast and away from the area Thursday night into Friday as the upper trough lifts northeast. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR right into Sunday. SHORT TERM: VFR conditions are likely Sunday night into early Monday night. Conditions may lower to IFR Downeast late Monday night as some low clouds begin to spread in from the south. IFR to MVFR conditions are likely Tuesday into Wednesday in low clouds, some drizzle, and showers Tuesday night into Wednesday. && .MARINE... NEAR TERM: No issues on the waters. Winds will remain light 5 to 10 kts into Sunday w/a turn to ese by the afternoon. Seas will range 1 to 2 ft especially in the intra-coastal zone. SHORT TERM: Winds are expected to be below SCA Sunday night into Monday night. South winds may reach SCA on Tuesday and seas will likely build in response to the southerly winds. A SCA or Gale will likely be needed Tuesday night into Wednesday for strong south winds. Seas will continue to build due to the southerly fetch possibly reaching 10-15 ft on Wednesday. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/Hewitt Short Term...Bloomer Long Term...Bloomer Aviation...CB/Hewitt/Bloomer Marine...CB/Hewitt/Bloomer
Area Forecast Discussion
National Weather Service Des Moines IA
627 PM CDT Sat Oct 21 2017 .SHORT TERM.../Tonight through Sunday/ Issued at 312 PM CDT Sat Oct 21 2017 The primary concern will obviously be convective trends into tonight. Confidence is high that showers and storms will blossom eventually due to the deep convergence and deep, strong thermodynamic and kinematic forcing with the long wave trough passage, but less so with respect to intensity. Storms developed in NW Iowa around 18z and looked as if they were going to mature fairly quickly, but since diminished. Additional convection has also developed farther south in a zone of strong frontal convergence and frontogenetical forcing, but this has also been somewhat slow to strengthen. Western Iowa RAP soundings show a 2km warm layer at the base of the EML continuing to erode and there may be a slim window for surface based convection to mature, but it will not last long as the front quickly undercuts anything resulting in convection being rooted around 1km. With plenty of stratus over Iowa and the loss of heating soon, feel much of the convection will be below severe limits unless trends increase soon. Shallow and deep shear parameters are both high so there remains a small potential for supercells and brief tornadoes in addition to hail and wind. QLCS tornadoes will be possible into the evening with low level shear persisting, but as mentioned overnight the 0-3km shear vectors are not oriented favorably: too far to the north vs east and line/front orientation. Small segments would need to orient NE to realize available shallow shear and SRH. Moderate to locally heavy rains may eventually be a greater threat with strong low level moisture transport ahead of the front. 00Z NAEFS precipitable water, specific humidities and integrated water vapor transport are all near climatological extremes. Thus expect widespread efficient rains in 3.5+km warm cloud depths with 1 amounts over the SE half of the forecast area possible by tonight. Skies should clear into tomorrow as the system departs with temperatures 5 to 10 degrees cooler than today. The biggest change will be less humid conditions with surface dewpoints no better than the 30s and 40s. .LONG TERM.../Sunday night through Saturday/ Issued at 312 PM CDT Sat Oct 21 2017 The long term period begins with significant shortwave trough diving south through the Upper Midwest early next week. This will send a strong cold front through central Iowa during the morning and afternoon hours on Monday. Deep unidirectional winds and efficient boundary layer mixing behind the front should still be enough to warm temperatures into the upper 50s and low 60s. Not expecting anything more than isolated showers with the frontal passage as the atmosphere is starved of moisture. A reinforcing shot of cold air advection will lead to much cooler and blustery conditions on Tuesday. Model guidance remained consistent to the previous forecast with highs only in the upper 40s and low 50s. A bounce back to near average temperatures is expected through the middle of the week as an upper level ridge builds over the Plains states. The warm up will be short lived as a deep upper level low digs southeast and dislodges a large dome of cold air to our north. The GFS and EC remain out of sync with their timing and evolution of the trough, although the slower EC has trended toward the faster GFS with the latest run. Regardless of any model discrepancies, there is high confidence that the coldest air we have seen so far this season will be ushered in by a strong cold frontal passage in the late Thursday or Friday time frame. Latest guidance suggests highs will struggle to get out of the 40s on Friday and Saturday with below freezing temperatures possible overnight. Light rain and/or a few snow flakes are also possible Friday night into Saturday as moisture wraps around the back side of the upper level low. At this time it looks like the better lift/moisture will slide north of the area. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 627 PM CDT Sat Oct 21 2017 Broken line of convection with occasional MVFR cigs moving across area now...and will exit the far east by 10-12z Sunday. Activity may increase southeast overnight near KOTM as low level jet increases aft 03z. Some wind and mainly MVFR VSBY reduction as storms roll through. Aft 06-10z nearly all areas will be VFR with either high clouds or skc aft 12z. Winds increase aft 15z with gusts near 16-18kt until 21z. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Small LONG TERM...Martin AVIATION...REV
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
917 PM CDT Sat Oct 21 2017 .UPDATE... The much talked about cold front is currently headed south and located across a Wichita Falls to Odessa, Texas line. Along it, strong to severe thunderstorms are ongoing across north Texas and Oklahoma. However, as the front continues to shift south, the stronger lift and forcing dynamics will remain north in association to the vorticity maximum over Oklahoma. Wile SPC mesoanalysis and suggested GFS/NAM BUFR soundings indicate upwards of 2000 J/KG of MLCAPE over the region, a strong cap is also in place per these same sources. Furthermore, aircraft data out of Austin and San Antonio also indicate the presence of the capping inversion. This will keep any pre-frontal activity at bay through the evening. The showers over San Saba to Comanche Counties north of the area are elevated in nature due to the overspreading of weak upper-level divergence. RAP mass fields indicate surface convergence will weaken as the front passes through the region while the best mid- and upper-level support lag behind. A strong thunderstorm or two may still be possible with the passage of the front overnight but overall trends appear to suggest only pockets of brief heavy rain and general thunderstorms along a Fredericksburg to Giddings line and north. Have reduced rain chances farther west and south through the overnight. The front should be through the entire area by late morning to near noon Sunday with gusty north winds but clearing skies. && .PREV DISCUSSION... /ISSUED 717 PM CDT Sat Oct 21 2017/ AVIATION... /00Z TAFS/ Vfr skies remain expected through the evening with some areas of 1000-2000 ft cigs expected after midnight. Lowest cigs should be limited to the higher terrain areas. A brief dip into ifr could be possible right as the cold front arrives and areas of convection congregate along the front. Frontal timing appears to be consistent among the past several runs of rapid refresh models. Regarding the potential for TSRA, would suspect that we`ll no longer need to consider the TSRA prevailing at SAT/SSF by the 06Z update given the mesoscale trends in the HRRR. However, have found that the convective handling of the HRRR runs around the 00z init time often deviate from the broader consensus of qpf for some reason. Thus will stick with the earlier foreast trends and modify late this evening should the 00Z runs reflect the decreasing TSRA potential. Post-frontal sky conditions should improve rapidly Sunday morning given the deep layer of northerly winds behind the font. PREV DISCUSSION... /ISSUED 252 PM CDT Sat Oct 21 2017/ SHORT TERM (Tonight through Sunday Night)... For the rest of the afternoon, a weak embedded disturbance within the larger shortwave has disturbed CU fields enough to produce some showers along and just east of the I-35 corridor near Austin and Georgetown. Proximity soundings from just about all models show the cap holding on to prevent much in the way of anything more than a very isolated thunder chance but included slight chc PoPs for this area and east for the rest of the afternoon. The bigger forecast focus is the approaching cold front overnight tonight that will trek across Texas and reach the northern CWA likely just before dawn. The TTU-WRF has been consistent with timing of the front while the HRRRX continues to speed up and generate more convection with each run. Looking at the current speed of the front, do think the faster HRRRX is valid thus have slightly sped up the fronts arrival in the grids but only about an hour or so. As far shower and thunderstorm potential, the main threat will be gusty winds and not much else for hazards. Just about every CAM produces healthy outflow with convection firing in northern Texas, and with the faster trends in the front as seen in the HRRRX previously noted, this would further add confidence in gusty winds and limit any hail potential. Still seems to be some disagreement in the western extent of the convective line. SPCs SSEO guidance shows enough outcomes extending into the Plateau and Hill Country to warrant at least chance PoPs during fropa Sunday morning. Thus have reflected as such in the grids. The front should be clear of the CWA by 18Z, resulting in a breezy, mild day Sunday afternoon. Did bump up gust potential to a max of 30 mph late morning and mid day as a fairly strong pressure gradient looks to be in place post fropa. These should die down by the evening and allow for a very favorable radiational cooling set up with high pressure, light winds, and clear skies. Thus, lowered min T for Monday morning to the lower end of the ECM and MEN ensemble guidance. LONG TERM (Monday through Saturday)... A rather benign weather pattern for much of the week as Sunday`s front dries out the area and gradual warming occurs through mid week. Another cold front is progged to push through the area Friday which may be a more significant temperature changer for South Central Texas. At current, extended guidance shows highs next weekend struggling to exceed 70 degrees at least for the northern CWA. Still some model disagreement in timing and strength this far out so left this to the SuperBlend for now. However, no hazards are expected through the extended. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 65 77 50 83 55 / 80 20 0 0 0 Austin Bergstrom Intl Airport 65 79 47 83 53 / 80 20 0 0 0 New Braunfels Muni Airport 66 81 47 82 53 / 50 30 0 0 0 Burnet Muni Airport 60 77 45 81 52 / 90 10 0 0 0 Del Rio Intl Airport 64 81 51 83 56 / 10 - 0 0 0 Georgetown Muni Airport 63 76 46 82 53 / 90 20 0 0 0 Hondo Muni Airport 67 85 46 83 52 / 20 10 0 0 0 San Marcos Muni Airport 66 81 47 83 53 / 60 30 0 0 0 La Grange - Fayette Regional 68 79 47 81 55 / 70 60 0 0 0 San Antonio Intl Airport 67 82 49 82 55 / 30 20 0 0 0 Stinson Muni Airport 68 85 50 83 55 / 30 20 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Oaks Synoptic/Grids...Allen
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
939 PM CDT Sat Oct 21 2017 .UPDATE... Issued at 918 PM CDT Sat Oct 21 2017 A cold front was moving southeastward through northwestern MO this evening. A line of convection was along this front with trailing stratiform precipitation behind it. Isolated showers had recently developed across parts of northeast and central MO well ahead of the cold front. The line of convection will gradually weaken as it moves into northeast and central MO around midnight due to waning instability, but could still generate brief heavy downpours along with strong gusty winds. Looking at the latest HRRR model runs this convection will not likely get into the St Louis metro area until very late tonight and early Sunday morning, and by this time should have weakened quite a bit and be mainly in the form of disorganized scattered showers. Unseasonably warm temperatures can be expected tonight ahead of the cold front, particularly across southeast and east central MO and southwest IL due to the cloud cover, gusty southerly winds, and relatively high surface dew points. Lows in St Louis metro area tonight will be around 15 degrees above normal. GKS && .SHORT TERM... (Through Late Sunday Afternoon) Issued at 308 PM CDT Sat Oct 21 2017 Main issue continues to be the cold front that will slide east across region tonight through midday on Sunday. Models have decent sfc based CAPEs thru this evening, then diminish quickly after 06z. With slower onset of precipitation and weakening instability, feel that as line of storms approach CWA, they will weaken and expect mainly widespread showers and isolated thunderstorms with passage of front. Still not ruling out isolated strong to severe storms for portions of central/northeast MO late this evening. Models now more in agreement with upper level trof deepening and cutting off late in the day on Sunday. This will slow exit of activity on back side of system, especially for eastern half of forecast area. As for temperatures, will see mild lows for one more night, in the low 50s to mid 60s. Then on Sunday, morning highs in the low 60s to low 70s, then steady or falling temperatures during the afternoon hours. Byrd .LONG TERM... (Sunday Night through Next Saturday) Issued at 308 PM CDT Sat Oct 21 2017 Period begins with amplified flow as a deep trof becomes cut off across the region. Mdls are still struggling with this feature. However, the 12z guidance is in much better agreement than prev cycles and confidence is building. Still, have kept low PoPs on Mon to account for a potential slower soln. After a brief warmup on Mon, another cdfnt pushes thru the region Mon afternoon as a deep low develops over the Great Lakes region. The area shud remain seasonable cool with reinforcing shots of cold air. A couple of clippers will help to warm temps as well. Mdls differ late in the period with exactly how much cold air will arrive Fri into Sat as another cdfnt pushes thru the region. The GFS/ECMWF both point to low chances of snow Fri night into Sat, perhaps even longer into Sat morning than currently forecast. A lot can change between now and next weekend, but will be an event to monitor. Tilly && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 526 PM CDT Sat Oct 21 2017 Cold front extending from MN south through extreme northwestern MO into western OK will move southeastward through the taf sites late tonight and Sunday morning. There was a line of thunderstorms along this front which will move into UIN and COU late this evening near midnight, and eventually into the St Louis metro area by early Sunday morning. The convection should slowly weaken in intensity late tonight as the instability wanes. There may also be isolated showers ahead of the cold front which could impact the taf sites this evening. Lingering light showers may continue in UIN and COU during at least much of Sunday morning and in the St Louis metro area Sunday afternoon due to a slow moving upper level disturbance behind the cold front. MVFR cigs will advect into the taf sites late tonight and early Sunday morning along and behind the cold front. The ceiling should gradually improve to VFR conditions Sunday afternoon. The southerly surface winds will veer around to a northwesterly direction after fropa in UIN and COU towards early Sunday morning and in the St Louis metro area by early Sunday afternoon. There will be a strong southwesterly low level jet tonight which will lead to some LLWS conditions at the taf sites, but it appears that there will be enough nocturnal mixing to keep the surface wind up so it will not likely be strong enough to include in the tafs. SPECIFICS FOR KSTL: Cold front extending from MN south through extreme northwestern MO into western OK will move southeastward through the STL area Sunday morning. There was a line of thunderstorms along this front which will move into the STL area by early Sunday morning. The convection should slowly weaken in intensity late tonight as the instability wanes. There may also be isolated showers ahead of the cold front which could impact STL this evening. Lingering light showers may continue in the STL area Sunday afternoon due to a slow moving upper level disturbance behind the cold front. MVFR cigs will advect into the STL area late tonight and early Sunday morning along and behind the cold front. The ceiling should gradually improve to VFR conditions Sunday afternoon. The southerly surface winds will veer around to a northwesterly direction after fropa by early Sunday afternoon. There will be a strong southwesterly low level jet tonight which will lead to some LLWS conditions, but it appears that there will be enough nocturnal mixing to keep the surface wind up so it will not likely be strong enough to include in the tafs. GKS && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 64 66 50 70 / 90 90 30 10 Quincy 57 61 45 68 / 100 70 5 0 Columbia 55 61 44 70 / 100 60 5 0 Jefferson City 57 62 43 71 / 100 70 5 5 Salem 64 72 50 67 / 60 90 60 40 Farmington 63 67 47 70 / 90 90 40 20 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
842 PM EDT Sat Oct 21 2017 .SYNOPSIS... High pressure will move east into the western Atlantic through Monday. Low pressure and its attendant cold front will sweep through the area Tuesday. Troughing will remain overhead for much of the second half of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... High pressure resudes across the Northeast and Mid Atlantic section of the CONUS. In spite of this, ample upper level moisture has drifed atop the ridge, resulting in a deck of cirrus. Skies became mostly cloudy if not cloudy just prior to sunset, and remains so at this time. IR satellite and RAP Bufkit overview suggest there will be little change until the pre-dawn hours. Have made these adjustments in the sky grids. Will be assessing if low temperatures need to be bumped up slightly shortly. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Quiet wx Sun-Sun night under high pressure. Clouds begin to increase Mon with showers expected by midday on the west and spreading east through the afternoon. Heavy showers with possible t-storms and gusty winds Mon night as cdfnt enters the area. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Strong front moving through Tuesday is main story in long term. This system looks potent with potential for a period of heavy, wind swept rain ahead of and along the primary cold front. Strong southerly fetch ahead of it should bring copious moisture north, but speed should limit flood concern. Gusty winds possible with very strong low level jet, but most likely any winds of a threatening nature will be limited to the cold frontal passage itself - low topped squalls possibly embedded within larger rain band is the concern. Timing remains a bit uncertain but right now, its favoring the AM. Breezy and much cooler behind the front, with the coolest days likely Wednesday-Thursday. Some freeze issues are possible, though this cold shot looks very transitory and if it doesn`t align with a good radiational night, it just might be chilly versus freezing. Upper trough plus wraparound moisture might result in a few showers Wednesday as well, especially in the mountains. If its cold enough in the higher terrain, these could well be snow showers. Drying out and moderating Friday with high pressure building in. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... VFR conditions through Sunday evening. A southerly flow will strengthen ahead of a cold front overnight Sunday and Monday. Moisture streaming into the area will cause more clouds along with the possibility for subVFR cigs. Patchy fog is also possible overnight. The cold front will pass through overnight Monday into early Tuesday. LLWS is possible during this time. A soaking rain is also expected with the frontal passage and there is a potential for heavy rain and IFR cigs/vis, along with gusty winds - perhaps isolated 30-40 knot gusts. Timing still a bit uncertain but right now favoring between 06z-12z early Tuesday. After that, NW wind may be gusty, but becoming VFR overall for the rest of the week. A few showers possible, mainly Wednesday, but cig/vis reductions should be minimal. && .MARINE... Winds will begin to strengthen Mon in srly flow. SCA conditions likely by late Mon and solid SCA conditions expected Tue. Gales possible Tuesday as strong cold front barrells through. SCA possible Wednesday as the system moves away and high pressure builds in. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...LFR NEAR TERM...HTS SHORT TERM...LFR LONG TERM...RCM AVIATION...BJL/RCM MARINE...RCM/LFR
Area Forecast Discussion
National Weather Service Memphis TN
934 PM CDT Sat Oct 21 2017 .UPDATE... Mostly cloudy conditions prevail over much of the region this evening, with some shower activity ongoing across northwest Mississippi. Temperatures are in the lower 70s, while winds are out of the southeast. Slightly increased POPs to account for latest radar trends and HRRR guidance through midnight. Otherwise the forecast is on track at this time and requires no further updates. ZDM && .PREV DISCUSSION... /issued 238 PM CDT Sat Oct 21 2017/ DISCUSSION... Breezy and mild conditions this afternoon as pressures fall ahead of the approaching front/upper trough in the Central Plains. Temperatures this hour were in the upper 70s to low 80s...with a few stations seeing dewpoints cresting 60F. Skies were a mix of clouds and sun. For tonight through Monday...models are in good agreement with a faster solution for the shortwave trough in the Plains to briefly become a closed low at 500mb in the Ozarks late tonight...then sliding east into the Ohio Valley and quickly dampening by Monday afternoon. Thus most Midsouth locations will see a window of 20-24 hours of precipitation...with points east of the Mississippi River receiving upwards of 3 inches. A welcoming need. The best instability with the associated cold front will be confined to areas west of I-55 from roughly 10-18z tomorrow morning...with the focus quickly shifting to points south of I-20 beyond this time. Moderate to heavier showers though will remain well into the night across portions of west Tennessee and north Mississippi. By Monday westerly surface winds will begin drying the region...with brief break before the next wave and front arrive on Tuesday. Only the far east may see lingering clouds and a few isolated showers. The downsloping winds off the Ozarks should raise temperatures to the low 70s in the west....while the east stays in the 60s. Tuesday through next weekend...models this period slowly begin to diverge. Initially a second reinforcing cold front will slide through the area with very little moisture left to work with. Timing of this boundary on Tuesday may pose a tricky temperature forecast. Behind the front northwesterly winds will make it blustery across the north where 60F for a high may be a struggle. Diminishing winds overnight will lead to the best chance during the week for patchy frost to form in the east. Surface high pressure will remain in control Wednesday and Thursday with winds slowly becoming southerly. Highs will warm from the low to mid the upper 60s to the mid 70s. Clouds will be on the increase as the next shortwave and Canadian airmass drops into the Upper Midwest by Friday. The axis position of this wave differs considerably between the GFS and ECMWF...with the GFS farther east...cooler and less precipitation. The mean ensemble members show this trend as well. The Euro places a longer period of southwesterly flow over the region and warmer temperatures. Have leaned with the cooler and drier GFS. JAB && .AVIATION... /00z TAFs/ A few thunderstorms continue to the SW of KCKM but should have no impact on forecast terminals this evening. Generally benign conditions are expected over the next 8-10 hrs although S to SE winds will increase as the low-level jet intensifies. A line of showers and thunderstorms will move from west to east across the Mid-South early Sunday and VCTS was included at all TAF sites. In addition to convection, MVFR (and potentially brief IFR) conditions are expected across most of the area through at least midday, if not well into the afternoon hours. Johnson && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Miami FL
812 PM EDT Sat Oct 21 2017 .UPDATE... Surface high pressure over the mid Atlantic will continue to generate moderate to strong easterly flow over South Florida tonight. Expect winds sustained generally between 10 to 15 mph along the east coast metro region, increasing again by mid Sunday morning. Latest NWS radar loop indicates light to occasional moderate showers advecting onshore from the Atlantic. Instability parameters still appear rather weak, so have not included any mention of thunder in the update. Short term models, such as the HRRR and WRF show isolated showers persisting through the night, so have adjusted PoPs accordingly. && .PREV DISCUSSION... /issued 405 PM EDT Sat Oct 21 2017/ DISCUSSION... Latest WPC surface analysis shows a strong 1029 mb cell of high pressure over the mid Atlantic region, with a weak stationary boundary draped across the Bahamas. The combination of these two feature has tightened the surface pressure gradient across South Floria and increased easterly winds today. On average, winds along the Atlantic coast have been sustained 20 to 30 mph, slightly weaker inland. Satellite derived PWAT values are from 1.6"-1.7", with a majority of the moisture located in the lower and upper levels of the atmosphere. Weak instability has allowed for quick, westward moving, light to moderate showers over the peninsula. Not expecting any lightning with this activity, so have removed mention from the latest forecast package. With little changing synoptically tonight, expect gusty easterly winds to continue along the east coast metro region, generally around 15 mph. Sunday through mid next week: Models begin to slowly shift the aforementioned surface high eastward towards the mid Atlantic ocean. In response, flow will turn east southeasterly, then eventually south southeasterly. Winds will remain breezy through the period, especially along the east coast beaches and metro regions. Mid range models prog a low pressure trough to deepen over the Ohio valley, dragging a sharp cold front southward over the Gulf. As this system begins to approach Florida late Monday, moisture will begin to pool ahead of the front. The GFS forecast PWATs increase to around 2.00" over our region. Intability associated with the approaching front will also increase. Thus, expect elevated chances for showers and thunderstorms Tuesday into early Wednesday across the entire CWA. Late into Friday: Behind the frontal passage, much drier and cooler conditions will ensue. Maximum temperatures are forecast only in the lower 80s on Wednesday, then struggle to reach 80 degrees on Thursday. Dry weather is expected, along with dewpoints plummeting into the 40s and 50s. This front is a sure sign that the end of the rainy season is near. MARINE... Pressure gradient between a decaying front over the region and high pressure over the southeastern United States will bring east wind of 20 to 25 knots and seas of 5 to 7 feet for much of the waters through the weekend. A small craft advisory remains in effect over the Atlantic waters and outer Gulf waters through early Sunday morning. AVIATION... Scattered showers streaming westward across much of South Florida should continue overnight. Activity has approached Naples more than anticipated so added VCSH for KAPF from 20-0z. Easterly wind gusts are likely to exceed 25 KT through sunset, then diminish slightly overnight, before increasing again by mid-morning Sunday. Shower chances drop off after daybreak Sunday, so for now have left dry TAFs for FLL and Miami-Dade terminals. VFR should prevail but periods of MVFR (mainly CIGs) quite possible, especially through the afternoon. BEACH FORECAST... Persistent easterly flow will allow the high risk of rip currents to persist through the weekend into early parts of the work week. The flooding along the east coast during high tide should begin to decrease over the next several cycles as the new moon phase ends. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 78 88 80 86 / 40 30 40 30 Fort Lauderdale 80 87 80 87 / 40 30 40 30 Miami 79 89 79 87 / 40 30 30 40 Naples 75 91 76 84 / 20 20 10 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Sunday evening for FLZ168-172-173. AM...Small Craft Advisory until 6 AM EDT Sunday for AMZ650-651-670- 671. GM...Small Craft Advisory until 6 AM EDT Sunday for GMZ676. && UPDATE...27/JT DISCUSSION...27/JT MARINE...27/JT AVIATION...17/AR BEACH FORECAST...27/JT
Area Forecast Discussion
National Weather Service Melbourne FL
936 PM EDT Sat Oct 21 2017 .UPDATE... It was rather quiet today as far rainfall with only isolated showers producing trace amounts to only a few hundredths of an inch of rainfall across the area. For the rest of tonight, drier air mass will gradually erode as moisture is forecast to increase from south to north in response to the lower-level winds turning more southeasterly. Already beginning to see evidence of the enhanced moisture with isolated showers developing across and just offshore of Martin county. Both the HRRR and local WRF show isolated to scattered shower activity gradually spreading northward across the Treasure Coast into Brevard county through the overnight. Inherited forecast in good shape with 40% PoPs across southern Martin county with 30% continuing through the Treasure Coast, Brevard, and coastal Volusia counties. Low temperatures will be in the low 70s inland and mid 70s with a few upper 70s possible along the coast. && .AVIATION... Mainly VFR. Drier air will gradually moisten with showers expected to gradually increase along the coast from south to north during the overnight. Interior terminals should expect shower activity and perhaps a thunderstorm by late morning/early afternoon on Sunday. && .MARINE... (previous discussion) Poor to hazardous boating conditions will continue tonight with east winds 15-20 knots and seas up to 7 feet. Winds begin to veer out of the SE Sunday then more southerly Monday as high pressure ridge pushes seaward and a strong cold front approaches from the west. Pressure gradient will support wind speeds 13-18KT with seas 4FT near shore and 5-6FT well offshore. Some increase in SW-W winds to near 20KT north of the Cape Tuesday, however offshore component keeps seas no higher than 4-5FT well offshore. Brief NW wind surge Tuesday night into Wednesday will push seas up to around 7FT in the Gulf stream, before they subside by Thu. && .PRELIMINARY POINT TEMPS/POPS... DAB 73 85 73 86 / 20 50 40 50 MCO 72 88 72 87 / 10 50 20 50 MLB 78 87 76 86 / 30 50 30 40 VRB 77 87 75 86 / 30 50 30 40 LEE 71 88 72 86 / 10 50 20 50 SFB 71 87 73 87 / 10 50 20 50 ORL 72 88 73 88 / 10 50 20 50 FPR 77 86 75 86 / 30 40 30 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory until 10 AM EDT Sunday for Flagler Beach to Volusia-Brevard County Line 20-60 nm-Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet 20- 60 nm-Volusia-Brevard County Line to Sebastian Inlet 0-20 nm-Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. && $$ UPDATE/AVIATION...Combs RADAR/IMPACT WX....Lascody
Area Forecast Discussion
National Weather Service San Angelo TX
814 PM CDT Sat Oct 21 2017 .UPDATE... Severe thunderstorm watch number 505 now in effect through 2 AM Sunday morning, for most of the Big Country and, the norther4n two Heartland counties, and Runnels county. Just sent a new zone forecast package to include a watch headline for those counties. && .PREV DISCUSSION... /issued 647 PM CDT Sat Oct 21 2017/ AVIATION... /00Z TAFS/ Look for VFR conditions to dominate through 00Z tomorrow, with thunderstorms along and ahead of a cold front this evening and later tonight. Expect the cold front at the Abilene terminal around 05Z and at the San Angelo terminal about an hour later. PREV DISCUSSION... /issued 313 PM CDT Sat Oct 21 2017/ SHORT TERM... (Tonight and Sunday) .Severe Storms Possible This evening... An upper level trough and associated cold front will be the main focus in the short term, with the potential for some severe storms later this evening. At the surface this afternoon, a cold front was moving south and currently located across the southern Panhandle into northwest Oklahoma. A diffuse dryline/surface trough extended south across the eastern Low Rolling Plains and eastern Permain Basin. West Central Texas was located in the warm sector with good low level southerly flow. Also, good instability across the area with MLCAPES of 2500 J/KG. At the upper levels, a strong trough was located across the central and southern Rockies, with large scale ascent starting to increase across the Southern Plains. Expect scattered to numerous thunderstorms across mainly northern and eastern sections of West Central Texas tonight. The Hi Res models(HRRR, Texas Tech WRF) indicate scattered storms developing along the cold front and moving east across parts of the Big Country this evening. More isolated storms are possible further south along the dryline, mainly west of Sweetwater to San Angelo to Ozona line for late this afternoon and early evening. The HRRR model is the most aggressive with this possible development of convection. A few storms may be severe this evening, mainly across the Big Country, as vertical shear improves along with the instability. The main hazards will be large hail, damaging winds and dangerous lightning. After midnight, a line of storms are likely along the cold front across the Heartland and Northwest Hill Country. A few strong storms are still possible. For Sunday, expect a quiet forecast with gusty north winds for a few hours. Highs will be in the 70s. 21 LONG TERM... (Sunday night-Thursday) Expect a roller coaster of temperature this week as two cold fronts impact West Central Texas. The second cold front expected later this week may be the strongest of the season. Mostly dry weather is expected this week. Temperatures rebound on Monday into the lower to mid 80s after chilly morning lows in the 40s Sunday night. Then, a reinforcing cool front and associated surface high builds into the region Monday night. This will result in cool afternoon highs in the low to mid 70s Tuesday with morning lows again in the 40s on Wednesday. Afternoon highs climb into upper 70s Wednesday, and into the mid and upper 80s by Thursday. (Friday-Saturday) The GFS is more similar to the ECMWF solution with respect to the upper level and surface features. Both models now show an amplified ridge building just off the the Pacific Northwest coast by Friday. Models also prog a deep upper trough developing over the middle of the country and extending south into Texas. This type of upper flow should unleash the first Canadian front of this fall season into Texas. the two models show this front reaching West Central Texas by Friday morning. Afternoon high temperatures next Friday and Saturday may only reach the 60s. Morning lows on Saturday may drop into the upper 30s to near 40. We`ll continue to monitor the models as they continue to get a better handle on this potential Canadian Cold frontal surge. 26 && .PRELIMINARY POINT TEMPS/POPS... Abilene 54 73 47 82 / 50 5 0 0 San Angelo 55 76 46 84 / 40 5 0 0 Junction 58 77 41 83 / 60 5 0 0 Brownwood 56 75 43 83 / 80 5 0 0 Sweetwater 53 73 50 81 / 20 5 0 0 Ozona 55 75 43 81 / 40 0 0 0 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$