Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/21/17

Area Forecast Discussion
National Weather Service La Crosse WI
945 PM CDT Sat May 20 2017 .SHORT TERM...(This evening through Sunday) Issued at 316 PM CDT Sat May 20 2017 At 3 PM, dry slot was approaching the Interstate 90 corridor. This dry slot will provide some dry time for late this afternoon and early evening...then as the upper level low and occluded front moves through the area another band of rain will move through the region. With most unstable CAPES climbing up to 500 J/kg, there will be enough instability for isolated thunderstorms during the mid to late evening. The RAP soundings suggest that there may be brief window (1 to 2 hours) where there may be enough instability and 1-6 km shear for the potential of some hail. If this occurred, it would be in northeast Iowa and southwest Wisconsin. Warm air advection will allow temperatures to continue to rise this evening. As a result, our high temperatures for today will likely not occur until then. On Sunday, the closed low will move into northern Minnesota and northern Wisconsin. The cyclonic flow associated with low will keep skies cloudy across the region and there will be isolated to scattered showers mainly north of Interstate 90. .LONG TERM...(Sunday night through Saturday) Issued at 316 PM CDT Sat May 20 2017 From Sunday night into Wednesday, an upper level low will slowly transition southeast across the Upper Mississippi River Valley. This low will produce periodic showers. There will be enough instability on Monday and Monday evening (CAPES up to 1250 J/kg south of Interstate 90) and Tuesday afternoon and evening (CAPES up to 500 J/kg) for isolated to scattered thunderstorms to develop. With limited shear, not anticipating any severe weather with these storms. The heaviest rain will be south of Interstate 90 from Monday night into Tuesday. During this time frame, the rainfall amounts will be up to a half inch. From Wednesday night into Friday, a 500 mb ridge will provide dry weather and near-normal temperatures. On Friday night and Saturday, a short wave trough will be moving northeast out of the southern Plains. Most unstable CAPES will climb into the 1500 to 2500 J/kg range. However the shear remains weak, so not anticipating and severe weather. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 945 PM CDT Sat May 20 2017 Cigs: blanket of ifr/mvfr cigs holding across the region, and likely will stay that way into Sunday night. The sfc low responsible for the low clouds will gradually exit northward into southern Canada after 12z Mon-and not expecting a lot of improvement until it does. Expect some minor diurnal "bump up" Sun afternoon, with a better shot for clearing after 06z Mon. WX/Vsby: cold front associated with the low pressure system sliding northeast across the local area this evening. Forcing along the boundary should be enough to pop a few scattered showers, with some potential for thunder (better to the southeast of the TAF sites). Most of this shifts northeast after 06z. Had some reductions in vsbys from areas of drizzle earlier in the evening - most of which has shifted north with the isentropic lift. Some ifr/mvfr br still found north of the low/sfc front though - and could impact the TAF sites for a few hours post 06z. Will monitor and make adjustments as needed. Wind: east southeast will swing to the south then southwest by Sun afternoon as the low pulls away. Could be some gustiness to the southwest of the low. && .HYDROLOGY... Issued at 316 PM CDT Sat May 20 2017 River Flood Warnings continue along the Mississippi River at Wabasha, the Trempealeau River at Dodge, the Black River at Galesville, the Yellow River at Necedah, and along the Wisconsin River at Castle Rock Dam as runoff from the very heavy rain earlier this week continues to move through the river system. Through Wednesday, an upper level low will provide periodic rain. The heaviest rain will be south of Interstate 90 from Monday night into Tuesday. During this time frame, the rainfall amounts will be up to a half inch. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Boyne LONG TERM...Boyne AVIATION...Rieck HYDROLOGY...Boyne
Area Forecast Discussion
National Weather Service State College PA
1130 PM EDT Sat May 20 2017 .SYNOPSIS... High pressure well to the north of the state will slide to the south and east tonight and be centered over the eastern seaboard on Sunday morning. Low pressure will move from the plains states into the upper Great Lakes Sunday and Monday. A cold front will push through the state later Monday. The weather will remain unsettled through the week as a large upper level trough advancing slowly from the midwest. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Subsidence inversion persists this evening with low broken to overcast now being overrun by increasing mid to high cloudiness from the west as upper ridge tracks eastward. Am not expecting substantial improvement overnight in areas where the clouds currently remain, as inversion trapping llvl moisture will keep mostly cloudy skies with isolated drizzle and the HRRR even indicating isolated showers traversing the north central and central mountains. Mid/high clouds will continue to increase overnight...while winds go light. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Expect most of the area to remain rain free for the balance of the day on Sunday. POPs will be high over the west as heights fall sufficiently there by the end of the day. The morning cloud debris overhead will probably hold temps down, but not as cool as Sat. A more- southerly wind will push temps into the m-u60s. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... A cold front should cross central Pennsylvania Sunday night into early Monday, accompanied by scattered showers and possibly some thunder. Looks like flow from the south (parallel to the front) will push a wave up the east coast during the day on Monday, with a period of moderate rain poss in eastern counties (though biggest impacts look to be east of CWA). Lighter precip ends from the west during the day. A weak area of high pressure will build in for Mon night and Tuesday with a cooler morning and maybe some patchy fog in store. Weather pattern turns unsettled again during the middle and later part of the week, as an upper-level low drops into the Great Lakes and surface low pressure develops over the Mid- Atlantic region. Light showers may begin to work into the region on Wed, with Thursday looking quite wet and dreary as a soaking rain looks likely. The upper-low should begin to lift out by Friday, allowing conditions to slowly improve. Light showers or drizzle may linger under the upper low on Friday keeping a coolness in the air. The weekend should bring a return of brighter skies, warmer temps and dry weather. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Low ceilings and stratus persist across almost all of Central Pennsylvania, except for KIPT, where skies are clear. Easterly flow continues and will likely keep the clouds over the region overnight. Fog is also beginning to develop, and have increased fog in the TAFs as well with the 03z updates. Will have to watch KIPT, as the potential of dense fog formation possible if skies remains clear there. Front makes slow progress eastward, and likely that rain will remain out of most TAF sites through 00z tomorrow except for KBFD and KJST. Here, introducing VCSH after 14z/15z, and prevailing SHRA after 21z. Slowly progressing front will mean widespread rain/showers and possible TSRA across the region Sunday Night into Monday, with gradual improvement west to east after frontal passage. .OUTLOOK... Mon...MVFR/IFR in SHRA/TSRA in the morning over the west and all day in the east. Tue...AM fog possible. Otherwise no sig wx. Tue PM-Wed...Restrictions developing with numerous showers and thunderstorms. Thu...Some restrictions AM Fog and possible showers. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...Dangelo LONG TERM...RXR AVIATION...Jung
Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
904 PM CDT Sat May 20 2017 .UPDATE... Issued at 904 PM CDT Sat May 20 2017 The back edge of the main area of rain is continuing to make steady progress northward this evening, as the dry slot evident in GOES-16 band 10 water vapor imagery continues to rotate northward. Steady rain should be confined to the northern part of the CWA for the rest of the night, with a south to north decreasing trend with time. With that said, there is still decent forcing for ascent within the dry slot as evidenced by redevelopment of showers from the MSP metro area into northwest Wisconsin. This is in an area of moderate forced ascent per QG diagnostics and decreasing stability, so we expect continued redevelopment of showers in this area for much of the night, just not the widespread steady rains of the past several hours. Finally, the rapid development of fog, very low stratus clouds, and drizzle has followed within an hour or so of the end of the steady rain, and this will likely spread northward with the leading edge of the dry slot aloft through the rest of the night. && .SHORT TERM...(This evening through Sunday) Issued at 401 PM CDT Sat May 20 2017 Light to moderate rain showers will continue to expand northward this afternoon and evening as a mid- to upper-level trough, characterized by upper-level diffluence and stronger isentropic lift at the mid-levels, will continue to ascend into the area. Some 850-700 mb layer warm air advection will also provide additional support for these rain showers. There have been reports of some sleet with the leading edge of the precipitation shield, which should continue through the afternoon, but taper off by the evening as warmer low-level air moves in. There is the potential for some thunderstorms, especially over northwest Wisconsin and adjacent counties of northeast Minnesota. MUCAPE instability values look to increase after midnight tonight due to steepening mid-level lapse rates. Winds will remain gusty into the evening and early Sunday morning hours before gradually weakening through the night-time hours. Strongest wind gusts will remain over adjacent locations near Lake Superior as winds remain from the east and northeast, providing better fetch to intensify these winds. The NAM model was indicating the potential for some light snow over Itasca and Koochiching Miller/Millercounties mainly after midnight. However, if it does occur, it should be brief, and not expected to lead to any accumulation as the sfc temperatures are just too warm for it. As the sfc low pressure center drifts closer to the region, there may be a brief period of drier conditions over northwest Wisconsin, due to a dry slot, mainly between 03z and 07z Sunday, as evidenced by the latest HRRR/NAMNest models. Reduced the POPs accordingly over this area. However, a corridor of positive vorticity advection will bring another round of showers of northwest Wisconsin after 07z, again as per the HRRR model. Rain showers should turn to more drizzle on Sunday, especially over our southern counties, due to decreasing moisture depth as seen in the 20.12z NAM/GFS soundings. The NAM soundings indicate the depth of the saturation layer to be around 6000 ft, which is sufficient moisture depth for drizzle. Moreover, Pwat values gradually decrease through the day Sunday. Still expecting chances of rain showers to linger over most of the Northland through the day Sunday, with the best chances lingering over the Iron Range and Arrowhead regions. Overall rainfall amounts up to three-quarters of an inch will be possible by Sunday evening. .LONG TERM...(Sunday night through Saturday) Issued at 355 PM CDT Sat May 20 2017 The large upper low over the region will continue to wobble slowly north Sunday night through Monday night, keeping a chilly airmass over the area with chances for rain/drizzle. Even as the low drifts farther away from the area on Tuesday, a shortwave dives into the area on the back side of the low to generate still more clouds and showers. With the cloud cover, temperatures will only get into the 50s both Monday and Tuesday, with overnight lows in the mid 30s to low 40s. Tuesday night there is potential for clearing and drier air to move into the area from the north, and with the north flow continuing, we are likely to have another cold night, with lows around freezing possible in the Arrowhead. We will have to watch this, as there may be need of a frost/freeze headline. This area got down around freezing the last two mornings, as well as a week ago so there probably won`t be much of an impact yet. Upper level ridging builds into the area for Wednesday and Thursday, which should bring us a period of warmer and drier weather for both days. However, towards Friday the ridge shifts far enough east to allow chances for rain to return to the area for Friday and Saturday. Would not be surprised to see this pushed later as the ridging pattern is somewhat blocky in nature and may slow down in later model runs. The return of southwest flow will also bring above normal temperatures back to the region for the later part of the week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 649 PM CDT Sat May 20 2017 Widespread light/moderate rain has spread across all terminals except KINL as of 2330z, and is expected to begin within the next few hours at KINL as low pressure over Iowa slowly moves northeastward through the 24 hour period. Confidence is rather high in conditions continuing to deteriorate to MVFR and eventually IFR in most location overnight and persist for much of Sunday. While widespread light/moderate rain is expected to diminish in coverage/intensity after the first 4-6 hours, the development of widespread low ceilings and fog is expected area- wide. Winds should slowly back to north and eventually northwest by the end of the period as the center of the low pressure area moves to Lake Superior. && .PRELIMINARY POINT TEMPS/POPS... DLH 37 48 40 56 / 100 70 50 30 INL 40 49 41 53 / 80 80 50 50 BRD 40 50 41 60 / 100 40 40 30 HYR 44 53 42 58 / 90 70 50 30 ASX 39 51 41 57 / 100 70 50 30 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 10 AM CDT Sunday for LSZ121-140>143- 146>148. Small Craft Advisory from midnight tonight to 10 AM CDT Sunday for LSZ144-145. Gale Warning until midnight CDT tonight for LSZ144-145. && $$ UPDATE...Miller SHORT TERM...JTS LONG TERM...LE AVIATION...Miller
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT Sat May 20 2017 .AVIATION... Main potential vorticity anomaly is shown to pivot aggressively to a negative tilt over the central Mississippi River Valley between 06- 12Z. This strongest of forcing is shown to miss the area to the west. However, rich lower tropospheric theta e content will bedrawn due northward out of the Ohio River Valley and eclipse or surge northward through western and central sections of lower Michigan. It is in this general vicinity that a secondary height fall maximum is shown to lift through as a triple point develops over southwestern Michigan under a boatload of 925-850mb frontogenesis. Midlevel lapse rates will be unimpressive at moist adiabatic or slightly better. Not expecting any strong thunderstorms tonight or explosive development. Latest timing has a glaciated cluster or ragged line of multicells pushing directly through semich in the 06- 10Z timeframe this morning. Some lingering light showers or drizzle is then expected through mid morning. The other timeframe to monitor will be after 20Z this afternoon when activity could re-initiate along the cold front slicing across the area. Latest forecast data continues to suggest this development will occur over far eastern lower Michigan east of the terminals. //DTW THRESHOLD PROBABILITIES... * High for ceiling aob 5000 feet tonight. * Moderate for thunderstorms between 06-08Z tonight. && .PREV DISCUSSION... Issued at 909 PM EDT Sat May 20 2017 UPDATE... A robust thunderstorm response this afternoon and early evening across portions of northwestern Indiana. This activity is being driven in the center of a mesoscale circulation and small height fall bullseye that is being kicked out ahead of the main vorticity anomaly going negative tilt over the mid Mississippi River Valley. It really is sort of messy tracing back but it appears the shortwave energy has a history back to previous convection yesterday over MO and AR. All things lining up for this response as NAM suggests this is on the northern edge of what should be strengthening 925-850mb frontogenesis and deformation. It is from this northern edge of the thunderstorm activity that an elevated triple point is forecasted to emerge over southwestern lower Michigan after 06Z tonight. Would not characterize this setup as one with a tremendous amount of dynamical forcing: detached well away from upper level Jet streak, removed from the most direct of cva, and no organized convergence maximum to the low level jet. Rather, it appears to be a good mix of prior convective vort max, subtle low level limiting streamline and north to south orientated convergence zone, and a surface warm front. Surface analysis places this surface cold front from portions of northeastern Illinois down into central Illinois. Middle 70s for temperatures and mid-upper 60s dewpoints has contributed to +1000 MLCAPE and approximately 1500 SBCAPE to the south of the boundary. SPC RAP based mesoanalysis depicts a very sharp instability gradient with little to no instability in place at this time across the northern couple of tier of counties in northern IN. Radar trends from KIWX support this initialization analysis as the most northern activity has been weakening or glaciating. The rest of tonight...Given the aggressive nature of the convective response thus far, feel the nam solutions with a deeper cyclonic circulation is the direction to hedge. Latest iterations of the HRRR are in agreement with steady northward development of showers and thunderstorms throughout the remainder of the evening hours. Best consensus would bring showers and thunderstorms to the doorstep of much of the western cwa (including Tri Cities) sometime around 5Z or soon after midnight. Strong easterly flow here over southeastern Michigan has a very cool and stable airmass in place (dewpoints are overwhelmingly in the 40s). Pouring through forecast soundings suggests little to no potential for surface based convection even as the warm advection kicks into overdrive. The reason for the high confidence in no surface based convection is that strong static stability will exist in the lowest 1800 ft agl through 12z. The RAP does suggest some potential for the existence of a steep midlevel lapse rate pocket despite a lack of one in the Mesoanalysis. Just enough cooling with height in the midlevels to potentially result in upwards of 750 J/kg of MUCAPE, particularly across the far southern cwa and Detroit. Farther north, all forecast soundings point to straight moist adiabatic. With the amount of moisture that is expected to converge over lower Michigan and the look of the forecast soundings there will be a heavy rainfall potential tonight. Would not be surprised at all if some locations were able to get a quick +1.00 of rainfall. The forecast message...showers and thundestorms becoming likely after midnight...primarily in the 5-9Z timeslot. Some potential exists for the activity to miss metro Detroit by scraping past to the NW. However, confidence in completely missing is low. The threats tonight for the strongest of storms will be small hail, heavy rainfall, and lightning. PREV DISCUSSION... Issued at 353 PM EDT Sat May 20 2017 DISCUSSION... MVC from earlier convection over the Plains is now lifting from southwest Michigan into Central Michigan, and should track through the Saginaw Valley during the very late afternoon and early evening. Showers and thunderstorms associated with this feature will continue to lift across the area, and should continue to exhibit a gradual weakening trend they encounter higher stability over Michigan. Overall, expecting high coverage of measurable rainfall. Large upper low over the Central Plains will slowly lift northeast through the upper Midwest late tonight and Sunday, and into Ontario by Monday. This system will provide a good chance for precipitation as it lifts to our west, with the main area of precipitation still expected to push across the area late tonight into Sunday. This will occur as the better moisture axis works through the area and a shortwave trough axis pivots through the Western and Central Great Lakes late tonight and Sunday. There looks to be a break in the forcing during the late morning to early afternoon, with some drier air also filling into the area, before the cold front sweeps across the area later in the day. Extent and strength of any second round of convection will depend, per usual in Michigan, on how much we can destabilize before the frontal passage and perhaps even on how much dry air becomes entrained into the boundary layer. NAM/GFS show activity becoming surface-based after some daytime heating, with about 500-1200 J/kg of SBCAPE able to build from roughly Flint east by the time the cold front works across late in the day. (This is assuming we reach forecast highs.) Skinny CAPE profiles and not too impressive wind field should limit the threat for severe storms. Temperatures will be a little tricky given muddled start to day, but southerly flow ushering in warmer air ahead of the front and mild start to the day should translate to max temps in the 70s. Another strong shortwave looks to pivot through Central/Northern Michigan as it rotates around the upper low over Ontario on Monday. Forcing and moisture from this feature looks to remain primarily north of the area however, and expect that is where precipitation will remain. More noteworthy item for Monday will be the development of breezy conditions once again as a westerly gradient tightens between surface low pressure over Ontario and high pressure strengthening over the Plains and Ohio Valley. Temperatures will cool in the post-frontal airmass on Monday, reaching into the 60s, which is just slightly below seasonal normals. Mid-level troughing in association with an cut-off low will bring rain chances for much of the extended period. A surface low pushing east from IL/WI into lower Michigan will start off by bringing rain chances Tuesday into Wednesday. The cut-off low is then expected to be stationed over or near the Ohio Valley, and will spin-up a series of upper-level disturbances which will bring additional chances for pop-up showers Wednesday into Thursday. While a rumble of thunder may be possible embedded in a shower or two, stability parameters remain not all that impressive, thus general thunder chances have been left out of the forecast. As the cut-off low moves east into New England, upper-level ridging is then expected to settle across the North Central Plains and Great Lakes through Friday and Saturday, which will act to diminish rain chances. A warming trend is also looking more probable for Memorial Day weekend. Expect daytime highs peaking in the 60s during the middle of the week, with a warm-up into the 70s for both Friday and Saturday. MARINE... High pressure over the eastern Great Lakes and low pressure over the Midwest will combine to support continued moderate easterly wind early tonight. Small craft advisories remain in effect through the evening before a weakening and veering wind trend develops overnight. This will shift stronger wind over north sections of Lake Huron through Sunday as a weak cold front moves through the region. Southwest flow will then strengthen during Monday as low pressure stalls and deepens north of Lake Superior. This will likely produce wind exceeding small craft advisory levels on Saginaw Bay before diminishing Monday night. The middle of the week looks unsettled in terms of rain as another low pressure system develops over Missouri Tuesday and moves into Lower Michigan Wednesday. HYDROLOGY... A weakening pattern of showers with isolated thunderstorms will move through SE Michigan during late afternoon. Locally heavy downpours with this activity will be capable of a quick 0.25 inch of rainfall. This will be followed by a break in coverage through most of the evening before another round of showers and storms develops toward midnight and lasts through mid Sunday morning. There will be a better chance of thunderstorms and heavy rainfall during this time. Additional amounts of 0.25 to 0.75 will be possible producing totals up to 1 inch in spots. The break between the late afternoon and overnight activity will minimize potential for flooding, although some ponding on area roads and in prone areas will be possible. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....CB UPDATE.......CB DISCUSSION...HLO/AM MARINE.......BT HYDROLOGY....BT You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
632 PM CDT Sat May 20 2017 .AVIATION... The cold front that produced showers and thunderstorms throughout South Central Texas today has pushed south of the terminals towards the Texas Coast. Because of this convection has ended with storms not expected for most of the evening. VFR conditions will continue through the evening before status builds back in around 06z at all terminals. The HRRR and other high resolution models indicate showers returning to the area late tonight as the low level jet kicks in. Because of this vicinity showers has been added to all terminals (AUS/SAT/SSF/DRT). MVFR conditions and showers will continue through most of Sunday as well. Late Sunday into Sunday night showers and thunderstorms are expected to increase across South Central Texas again. For now will leave VCSH as timing and intensity vary depending on which high resolution model examined. Will let later TAF issuances refine the precipitation forecast for late Sunday at the terminals. Winds in general will be north at all terminals between 7 and 13 knots. && .PREV DISCUSSION... /ISSUED 329 PM CDT Sat May 20 2017/ SHORT TERM (Tonight through Sunday Night)... A cluster of strong thunderstorms with very heavy rain over Frio County is likely to continue to push to the east-southeast in the next few hours. This cluster of storms is being lingering there for hours at the tail end of the cold front. Storm total rainfall amounts over parts of Uvalde and Frio counties reached 6 to 8 inches of rain past 8 hours based on radar estimation numbers. There is the potential for isolated severe thunderstorms within the next few hours mainly along and south of Highway 90 where SPC has a severe thunderstorm watch in effect through 5 PM CDT. HiRes models are all over the place with the weather conditions expected for late this afternoon and evening. Went ahead with a blend of HRRR and RAP solutions where the cold front continues to push slowly to the southeast with slight chances for strong to severe thunderstorms to develop for the period with moderate confidence on locally heavy rain capable of producing localized flooding. There is a slight chance for elevated convection behind the front late this afternoon and evening across portion of the southern Edwards Plateau and Rio Grande with additional scattered showers and isolated thunderstorms along the Rio Grande Plains overnight. A second round of severe thunderstorms is possible along and west of Interstate 35 on Sunday as an upper level low pressure system over the northern Plains moves towards the Upper Midwest. The surface boundary/cold front is expected to stall or slowly push back to the north over the coastal Plains and brings southeasterly winds to the Rio Grande Plains. This combination will aid the development of strong to marginally severe thunderstorms capable of producing large hail and damaging wind gusts in addition of localized heavy rain. LONG TERM (Monday through Saturday)... The wet weather pattern continues into Monday as an upper level short-wave disturbance moves across the area and abundant Gulf moisture remains in place. Another cold front is forecast to push across the area Tuesday morning with chances of rain expected across the entire area. Weather conditions begin to improve Wednesday with dry weather expected through Saturday. Temperatures will be below normal values through the middle of the week and back to near normals by Thursday through the upcoming weekend. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 82 66 81 67 79 / 60 20 30 60 70 Austin Bergstrom Intl Airport 80 66 81 67 78 / 60 20 30 60 70 New Braunfels Muni Airport 79 67 81 67 80 / 60 20 30 70 70 Burnet Muni Airport 81 63 78 63 77 / 50 30 30 60 60 Del Rio Intl Airport 80 68 81 68 85 / 40 40 50 60 40 Georgetown Muni Airport 82 64 79 64 77 / 60 30 30 60 60 Hondo Muni Airport 79 69 82 68 82 / 80 20 30 70 50 San Marcos Muni Airport 77 67 80 66 79 / 60 20 30 60 70 La Grange - Fayette Regional 86 68 83 69 80 / 60 40 30 50 80 San Antonio Intl Airport 75 68 81 68 81 / 60 20 30 70 60 Stinson Muni Airport 79 69 82 69 81 / 60 30 30 70 60 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Treadway Synoptic/Grids...04 Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Grand Forks ND
851 PM CDT Sat May 20 2017 .UPDATE... Issued at 851 PM CDT Sat May 20 2017 No significant updates planned for the late evening. Arc of low stratus and light rain continues to wrap around the low pressure system lifting across far southern MN...having overspread most all of the FGF forecast area. HRRR updates show widepsread light rain over west central MN and the MN Lakes Country transitioning to more of a drizzle/mist/fog with embedded light rain after midnight...which is fairly consistent with the 00z NAM12 package. UPDATE Issued at 635 PM CDT Sat May 20 2017 Widespread and very light rain with some few hundredths of an inch accumulation has spread northward through the Grand Forks area and will continue a slow expansion into far northwest MN, northeast ND and at least the eastern half of the Devils lake Basin. Areas with a tenth of an inch or more have so far been confined to the south of a line from Cooperstown to Hillsboro to Fosston. Cloudy and cool conditions with periods of light rain and a steady northeast breeze should persist throughout the evening and overnight. The southern RRV and MN Lakes Country should continue to receive greater overall rainfall during the evening and overnight periods. && .SHORT TERM...(This evening through Sunday) Issued at 334 PM CDT Sat May 20 2017 Latest runs of the HRRR have been doing pretty well in showing the timing and north advance of the light rain shield. The light rain will reach the far northern RRV this evening. Dry low levels will continue to mean radar at first will be overdoing actual rain at the ground. Latest models do take upper low more north and over the Red River valley Sunday morning. Dry slot may work up into west central MN tonight, while a steady light rain continues in the RRV. Still looking like west edge of rain JMS-DVL. With this in mind not a lot of further changes were made to the grids. Main area of light rain will shift northeast Sunday, though lingering patches of sprinkles/drizzle may remain behind it. Rainfall amounts remain unchanged from prev thoughts with well under 0.10 inch DVL region to 0.25 to 0.50 GFK/FAR to a bit over 0.50 BJI/PKD/ADC region. .LONG TERM...(Sunday night through Saturday) Issued at 334 PM CDT Sat May 20 2017 Upper low moves remains over nrn MN Sunday night. Then a secondary short wave will drop south thru western half of ND and Monday helping to keep the upper low over nrn MN. Enough clearing may occur so that some sun will lead to destabilization Monday with heating and cause showers to form with the cold air aloft. Upper low/trough will exit area on Tuesday with improving conditions. For Wednesday...surface high pressure remains in control and the upper ridge begins to shift across the Dakotas and Minnesota. With return flow and the shifting of the upper ridge...expect temperatures to rebound with values in the low 70s. Otherwise by area of low pressure and trailing cold front begins crossing the region...with increased chances for showers or storms. Little temperature change is expected through the end of the period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 635 PM CDT Sat May 20 2017 Expect widespread MVFR conditions in low clouds and light rain across the central and southern Red River Basin...with areas of IFR CIGS developing during the overnight...especially along and south of a Jamestown to Fargo to Bemidji line. Across the Devils Lake Basin and northern Red River Basin expect areas of MVFR conditions in low clouds and very light rain. Patchy IFR conditions in low clouds and very light rain are possible from Grand Forks and Grafton...eastward into the Red Lakes during the early morning. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Gust SHORT TERM...Riddle LONG TERM...Hopkins/Riddle AVIATION...Gust
Area Forecast Discussion
National Weather Service Green Bay WI
1019 PM CDT Sat May 20 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Sunday Issued at 232 PM CDT Sat May 20 2017 The latest rap analysis and satellite/radar imagery show low pressure centered over western Iowa, and associated warm front extending east across central Illinois/Indiana early this afternoon. Arcing band of rain is lifting north across central Wisconsin, and approaching the Highway 29 corridor. Thunderstorms have remained well south of the area so far today, but the band of rain will continue to lift north through the afternoon and should approach the U.P. border by 00z. Behind the rain, spotty showers and some drizzle are occurring over Iowa and northern Illinois. As the low pressure tracks across the region, precip trends are the main forecast concern. Tonight...Low pressure will swing northeast into the northern Mississippi Valley and western Great Lakes by late tonight. Arcing band of light to moderate rain will lift north ahead of the low and across northern Wisconsin during the evening. Behind the band of rain, mid-level drying will drop inversion heights to 800-850mb, which will temporarily put a halt to the rainfall, but will likely leave areas of drizzle, low clouds, and possibly some fog. Then a occluded front will lift from southwest to northeast across the area late tonight. Some instability in the models along the boundary, and forcing via potent shortwave could bring another band of showers and a few thunderstorms to the area. As a result, removed thunder chances through midnight, but left the mention after midnight to account for this possibility. Lows only falling into the mid 40s north and low 50s south. Sunday...The occluded front will exit northeast Wisconsin by mid- morning, bringing an end to the widespread shower and isolated tstorm threat. The incoming dry slot should bring dry weather for the rest of the day to eastern WI. But moisture wrapping around the low will return occasional light showers to central and north- central WI, mainly during the afternoon. Highs will range from the low 50s over the west to around 60 in the east. .LONG TERM...Sunday Night Through Saturday Issued at 232 PM CDT Sat May 20 2017 Main forecast concerns include precipitation trends for the first half of the week, a period of dry weather late in the work week, and a warm-up by the weekend. A potent negatively-tilted short-wave trof will sweep across northern WI late Sunday night into early Monday, so have boosted pops to likely over north central WI during that period. Following that, a cold front is expected to shift across the forecast area later Monday into Monday night, then slow down or stall out as a surface wave lifts northeast along the boundary on Tuesday. Models all offer different timing with the wave, which will impact whether or not any significant rains impact the southeast part of the forecast area, or occur to our east. Canadian high pressure will build into the region midweek, with dry conditions expected from Wednesday night through at least Friday. Abundant sunshine will cause temperatures to moderate, with readings rising to above normal again by Friday and Saturday. Return flow on the back side of the high may bring a small chance of storms to our western CWA late Friday night or Saturday, but the best precipitation chances should hold off until Saturday night. && .AVIATION...for 06Z TAF Issuance Issued at 1019 PM CDT Sat May 20 2017 As a band of rain showers departs north of the state at midnight, another band of showers along a frontal boundary, with an isolated storm possible, will pass over the area late tonight. In between these bands of showers, widespread IFR/LIFR cigs with IFR/MVFR vsbys due to fog. Vsbys to improve after the fropa late tonight or Sunday morning with cigs gradually improving late Sunday morning into the afternoon to mainly mvfr levels. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......TDH
Area Forecast Discussion
National Weather Service Lincoln IL
919 PM CDT Sat May 20 2017 .UPDATE... Issued at 919 PM CDT Sat May 20 2017 Widely scattered showers and thunderstorms have developed in advance of a cold front across the Illinois River Valley this evening. Latest radar imagery continues to show the cells struggling to organize as daytime instability wanes...with the activity mainly confined to locations from Rushville southward. HRRR has been consistently showing scattered convection spreading E/NE across the remainder of the CWA by midnight, with showers ending from west to east overnight. && .SHORT TERM...(This evening through Sunday) ISSUED AT 300 PM CDT Sat May 20 2017 Warm front has pushed northward across most of the forecast area, and was just starting to come into the areas from Galesburg to Lacon at 2 pm. Quite a bit of thinning in the clouds has taken place south of the front, and SPC mesoanalysis shows surface based CAPE`s have reached 1500-2500 J/kg from about Bloomington southward, although some capping is still evident looking at mixed-layer CAPE. Initial line of convection has formed to our southeast and was tracking northeast into Indiana, which just some weak showers from around St. Louis southwest. Main issue for this part of the forecast will be with convective redevelopment ahead of the cold front, which is currently back in western Missouri. High-res models have been trying to focus on a couple bands of convection, one forming near I-57 during mid- afternoon and another one arriving early evening immediately ahead of the front. The NAM and HRRR support CAPE`s around 1000 J/kg through sunset across western Illinois as the line arrives, although the better shear lags behind just a bit. Still may see a broken line of stronger storms though, with the threat waning toward late evening. Most of the forecast area will be dry by about 3-4 am once the front passes. While Sunday should remain dry, the circulation around the departing low will keep a fair amount of cloudiness across the northern CWA. The Flash Flood Watch for Sangamon County was extended into Sunday morning, as hydrographs downstream of Spaulding Dam continue to show a steady rise. .LONG TERM...(Sunday night through Saturday) ISSUED AT 300 PM CDT Sat May 20 2017 The large upper low will slowly lift northeast early next week, with a secondary lobe of energy swinging into the Great Lakes Monday night into Tuesday. Scattered showers and a few thunderstorms will be possible with this system. The trough will continue to deepen as it moves into Illinois early Wednesday, and some cold-core showers will be possible mid-week as lapse rates steepen due to 500 mb temperatures down to -20C. Have included some isolated thunder mention in the grids Wednesday afternoon due to the steep lapse rates as well. The upper low will finally shift off to the east late in the week, allowing for a narrow ridge to build eastward from the Plains. Some discrepancies with the models late-week in terms of a shortwave coming out of the Rockies to help disrupt the ridge, with the ECMWF most aggressive with any associated rain activity. Have kept rain chances in the 20% range for now. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 645 PM CDT Sat May 20 2017 Central Illinois remains largely dry early this evening: however, latest radar imagery is beginning to show widely scattered showers developing well in advance of an approaching cold front from near KMQB to KPPQ. HRRR suggests these cells will become more numerous over the next few hours as they track northeastward toward the I-55 corridor. Will include VCTS at both KPIA and KSPI through 05z accordingly...but will hold off on any thunder mention further east until radar trends become better established. Any storms that develop will diminish toward midnight as the cold front pushes into the area. Forecast soundings continue to suggest a brief period of MVFR ceilings immediately behind the front...mainly at the eastern terminals. These clouds will rapidly clear out by 10z. After that...the main aviation challenge on Saturday will be potential MVFR ceilings spilling into KPIA/KBMI. Based on NAM forecast soundings...have lowered ceilings to MVFR at KPIA by 14z...then further east to KBMI by 17z. Further south...kept ceilings in the low VFR category through the day. && .ILX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Sunday morning for ILZ051. && $$ UPDATE...Barnes SHORT TERM...Geelhart LONG TERM...Geelhart AVIATION...Barnes
National Weather Service Jackson KY
1056 PM EDT Sat May 20 2017 .UPDATE... Issued at 1056 PM EDT SAT MAY 20 2017 Had some convection develop along left over outflow boundaries as mentioned earlier. Stuff has been avoiding southwest areas. However, widespread rain is now working into our southwest zones associated with a mid level wave pushing northward. This rain will continue to overspread the area overnight setting up a damp night and a damp start to Sunday for most of the area. Thunderstorm chances will be slowly diminishing overnight as instability diminishes with the widespread rain moving into the area. A few isolated storms will remain possible however. Updated temperature grids based on the rain cooled air in the east. Also, receiving numerous reports of significant flash flooding in Magoffin county associated with the ongoing flash flood warning. We may need to consider a flash flood watch if more significant rain threatens the area again. UPDATE Issued at 645 PM EDT SAT MAY 20 2017 All convection has shifted off to the north and east of the area with a lull expected through the early evening hours. A modest moisture gradient is in place across the area with areas near the Cumberland river in the southwest seeing dewpoints into the mid 50s, while dewpoints reside near 70 or higher to the north and northeast. With the dry air in the southwest, have removed any thunderstorm chances for the evening. Left some isolated pops in the areas with better moisture, but confidence is low if we will see new development. However, some left over boundaries have been noted in the area, so it wouldn`t take much to see some new development towards sunset. In fact, both the RAP and HRRR show this potential, so will leave some low end pops in over the next few hours. Also with the rain moving in tonight, models are fairly consistent with this idea, so have bumped pops up to categorical. && .SHORT TERM...(This evening through Sunday night) Issued at 418 PM EDT SAT MAY 20 2017 A warm front located just north of the CWA has kept warm southerly flow across the region today, and has recently been the epicenter of which isolated to scattered convection has developed. While storms are generally located along our northern periphery and moving out of the CWA as of 4pm, the continued presence of this warm/moist/unstable airmass cannot rule out some continued isolated development through this evening. Latest CAMs aren`t in very good agreement, but all of them do show that a few more developing storms are not completely out the question through this evening, so kept isolated mentioned through the evening. By this evening the warm front will begin to lift northward as surface low pressure moves northeast towards the Upper Great Lakes region overnight and pulls it with it. This movement will also drag a surface cold front farther eastward into Western KY overnight. This cold front will be the main concern throughout the short term portion of the forecast as it continues its track eastward, reaching and then passing across the eastern portion of the state Sunday evening through Sunday night, exiting by 12Z Monday. A line of convection has already developed across the western portion of the ahead of this frontal feature, and is poised to continue eastward ahead of the approaching front. Models are all in good agreement that convection, potentially widespread, will begin impacting our CWA overnight, with scattered to numerous convection continuing throughout the day Sunday, before the front finally pushes through. Once the front does pass over a location, temperatures will quickly drop and dry air will fill in within the matter of a couple of hours. This will result in a defining line as to where the front is, with a cut off to clouds and precip just behind. In fact, the pops are likely too broadbrushed for the cut off that will likely occur, but will keep them as such just given some uncertainty on timing. Latest forecast soundings continue to support heavy raining cells for the convection that occurs overnight and tomorrow, with the entire forecast column saturated from the ground up, but not a lot of forcing otherwise. This will eliminate most hail concerns, and winds are not overly impressive, but can`t rule out a few higher gusts in the heaviest storms. Continued to hype up flooding warning in HWO, as any high precip producing cells could cause problems, especially if multiple storms pass over the same locations, or across areas which have already been saturated from rains over the previous days. .LONG TERM...(Monday through Saturday) Issued at 345 PM EDT SAT MAY 20 2017 The models are in fair, but steadily growing, agreement with the highly amplified pattern that will affect the region through the extended portion of the forecast. The models depict a relatively deep trough over the heart of the continent at the start of the extended with Kentucky in mostly fast zonal mid level flow just to the south. This upper low will then proceed to consolidate to the southwest and start to dig through the Plains Tuesday night into Wednesday. As this occurs, several energy batches will drift over eastern Kentucky While the core of the low moves into the Ohio Valley. At this point, the models diverge more with the GFS closing off the low and settling over Kentucky while the ECMWF is also starting to close off, but further north - over Lake Michigan. Either way, plenty of additional energy will pour through the area to end the work week with some better consensus on moving the upper low to the Mid Atlantic region on Friday - though the ECMWF is significantly stronger at this point than the GFS. Heights will then start to rebound for Kentucky that evening and early Saturday, though still some energy will probably be working its way across the state late in the period. Sensible weather will feature a brief respite from the heat and humidity Monday, but return flow will quickly brings PoPs, in the form of showers and thunderstorms, back in later that night and Tuesday as sfc low pressure takes shape to the southwest - though somewhat cooler conditions will continue through the rest of the week. This low will then likely move through the area with heavy rain a concern in the far east as it slowly passes Tuesday night and Wednesday. Cooler wx follows to end the work week, but the high pressure that pushes into the area will not be that strong and additional showers will be possible on Saturday. Did not deviate too far from the blend temps for the extended as conditions look too damp for much of any terrain differences of note. Also kept the PoPs similar as the blend came in pretty reasonable. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 800 PM EDT SAT MAY 20 2017 Ceilings will come down overnight into Sunday morning as widespread rain spreads across eastern Kentucky. We may see a few brief periods of IFR conditions with the rain early Sunday morning, but expecting it to be mostly MVFR. The MVFR cigs may hold through much of the day as rain persist into the afternoon hours. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...JMW LONG TERM...GREIF AVIATION...KAS
Area Forecast Discussion
National Weather Service Memphis TN
855 PM CDT Sat May 20 2017 .DISCUSSION...Surface analysis this evening places a surface low over Iowa with a cold front extending south over Missouri and Western Arkansas. Regional WSR-88D radars indicate a majority of convective activity is occurring well east of the Mid-South over Middle/East Tennessee and Alabama. A few scattered showers are occurring along the front in Arkansas. As of 8 PM CDT, temperatures across the Mid-South are in the 70s at most locations. Latest HRRR and 00Z WRF indicate potential for any additional showers and thunderstorms may decrease in coverage as the cold front moves through the area overnight. At this time, isolated to perhaps scattered pops still seem reasonable for the remainder of the night. Will make some adjustments to account for short term trends. CJC && .PREV DISCUSSION... /issued 635 PM CDT Sat May 20 2017/ UPDATE... Updated to include the 00z aviation discussion. PREV DISCUSSION... /issued 257 PM CDT Sat May 20 2017/ DISCUSSION... Latest KNQA radar shows that most of the shower and thunderstorm activity has pushed east ahead of a gust front that pushed through Memphis this morning. The shower and thunderstorm activity is now located just east of the Tennessee River and across Northeast Mississippi. This activity will push further east by sunset. Thus will significantly reduce POPS across the area. Although, can`t rule out new development along the cold front that is currently pushing through Southern Missouri and Northern Arkansas. The likelihood seems rather low as the atmosphere across Northeast Arkansas as well as the rest of the CWA has been worked over from this morning`s activity. The cold front will push through the CWA tonight into Sunday. Cooler and drier air will begin to filter into the Mid-South behind the front. Some redevelopment of showers and thunderstorms will be possible across areas of West Tennessee near the Tennessee River and Northeast Mississippi on Sunday. Highs will be in the mid to upper 70s. High pressure will settle over the Mid-South Sunday Night into Monday providing pleasant conditions. Lows will be in the 50s with highs in the mid to upper 70s. Another cold front will begin to approach the area by Tuesday. In addition, a SFC low pressure may develop along the Gulf Coast and track northeastward into Alabama by Tuesday. As a result, chances for showers and thunderstorms will begin to occur Monday Night into Tuesday with best chances occurring across Northeast Arkansas and Northeast Mississippi. Much cooler temperatures will filter into the area behind the cold front. Highs on Wednesday will only be in the upper 60s for the most of the area as an upper trof is expected to bring light showers with a possible thunderstorm or two to the region. An upper ridge will begin to build into the Mid-South by the end of the week. As a result, a gradual warming trend is expected to occur from Thursday into early next weekend. KRM && .AVIATION... /00z TAFs/ Generally VFR will conditions will prevail through the evening hours with a few showers developing across the Mid-South. A cold front will approach the Mississippi River from the west after midnight, providing a final focus for showers. A few hours of low stratus will be possible with this boundary, persisting longer over northeast MS where warm-sector stratus is anticipated. Conditions should improve by mid/late morning as dry air advects into the Mid-South. Generally south winds at 5-8 kts will veer northwesterly at up to 10 kts once the front passes. Johnson && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Miami FL
726 PM EDT Sat May 20 2017 .AVIATION... VFR expected to prevail through the period. Best chances for convection on Sunday will be at APF where a Gulf sea breeze is expected to develop by early Sunday afternoon. Otherwise, easterly to southeasterly flow will continue at the east coast terminals. && .UPDATE... Latest visible satellite imagery shows mostly clear skies with a few fair weather cumulus and scattered patches of cirrus. NWS radar is quiet this evening with dry conditions prevailing. Brisk east winds are expected to continue overnight along the Atlantic coast with light winds for the interior. Other than loading in the latest short term wind guidance, and updating the sky grids to lessen cloud cover, all other variable appeared on track. && .PREV DISCUSSION... /issued 444 PM EDT Sat May 20 2017/ DISCUSSION... Through Sunday: A large dome of upper level high pressure can be observed on water vapor imagery stretching from the mid Atlantic coast to Bermuda. The 1018 mb surface high is sitting stagnant, beneath this feature. Clockwise motion around the high continues responsible for the persistent east southeast winds, mainly 10 to 15 mph. As noted on this mornings sounding, there is an extremely dry layer in the mid levels. This can be traced back to a Saharan dust layer, originating from Africa, advected in from the southeast flow. During the summer months, the SAL typically suppresses cloud cover and convection, as is the case today. Short term models, including the HRRR and Hi-Res WRF, show just enough moisture and instability to squeeze out an isolated shower or storm in along the Gulf Coast this afternoon. Otherwise, expecting dry conditions for the remainder of the CWA. Tonight, as diurnal heating ceases, so should the chance of precip. East winds may still be brisk along the Atlantic beaches, around 10 mph, but light elsewhere. On Sunday, synoptic conditions will be nearly identical as today, along with the SAL layer. Therefore, expecting similar weather to ensue. Surface high pressure will still reside to the northeast, with breezy easterly flow developing. The best chance of showers/ isolated thunderstorms will once again be over the northern interior and Gulf coast region. Maximum temperatures are forecast near normal for this time of year, upper 80s along the east coast metro and around 90s further west. Early to mid next week: Monday marks the beginning of synoptic pattern change. The GFS and ECMWF both begin to sag a long wave trough over the southern CONUS. This feature will push the aforementioned surface high eastward, weakening the flow across southern Florida. Weaker flow will allow for both the Gulf and Atlantic coast sea breezes to develop in the afternoon, creating convergent lift. Showers and storms, however, still appear to be limited to the central and northern interior with dry conditions along the coasts. As the week progresses, however, the front will edge closer and weaken. Wednesday/Thursday, as the flow turns more southerly, then southwesterly, deeper moisture will advect northward from the northern Carribean. As the atmosphere destabilizes, chances of showers and thunderstorms steadily increase during this time frame. The GFS pushes the front across the area late Thursday into Friday, but the ECMWF stalls the dieing front over South Florida. Still nearly a week out, confidence of timing remains low. MARINE... This weekend, surface high pressure near Bermuda will maintain brisk east to southeasterly flow. As a long wave trough begins to approach Florida early next week, the flow will subside and become more southerly. The chance of showers and thunderstorms will increase by mid next week as moisture deepens over the area. Waves will generally be 3 feet or lower through the period. BEACH FORECAST... This high risk of rip currents continues through Sunday evening along the Atlantic Beaches, as breezy easterly winds prevail. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 77 87 74 88 / 20 20 10 10 Fort Lauderdale 78 87 75 86 / 10 10 10 10 Miami 77 88 75 88 / 10 10 10 10 Naples 73 90 72 88 / 10 30 40 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Sunday evening for FLZ168-172-173. AM...None. GM...None. && UPDATE...27/JT AVIATION...02/RAG
Area Forecast Discussion
National Weather Service Marquette MI
643 PM EDT Sat May 20 2017 .SHORT TERM...(This evening through Sunday) Issued at 413 PM EDT SAT MAY 20 2017 WV imagery and RAP analysis indicated a mid/upper level trough through the plains with a well-defined shortwave over ern Nebraska. At the surface, low pressure was located over wrn IA with a warm front through cntrl IL. 300k-305k(800-650mb) isentropic lift ahead of the shrtwv and low supported a large area of rain from srn MN through cntrl WI that was lifting slowly northward. Very dry low level air ahead of the rain area has delayed the progress of the pcpn into Upper Michigan. Tonight into Sunday, expect the pcpn to gradually spread through Upper Michigan btwn 21z-00z with the main area lifting north of the area after 03z. As aggressive mid level dry slotting moves in overnight, the rain should diminish to drizzle as lower level 285k- 295k (900-800mb) isentropic continues. As the shortwave approaches Upper Michigan btwn 09z-15z with stronger qvector conv and steeper mid level lapse rates, expect another period of showers with some isold tsra possible. The pcpn should then diminish during the later morning into the afternoon with even a few peeks of sun possible as drier air movesino from the west. However, some additional wrap- around shra may move into the west late. Temps will recover into the mid and upper 50s . .LONG TERM...(Sunday night through Saturday) Issued at 258 PM EDT SAT MAY 20 2017 Overall forecast highlights include a cooler start to the week with periodic chances for rain showers as cut off energy lingers across the Upper Great Lakes region. Towards the end of the work week temperatures will begin to warm back up to near normal for this time of year with minimal chances for precipitation. We could see a few nights early in the week where overnight lows drop low enough to possibly warrant frost headlines. Expect rain showers to linger across the area Sunday night and through the day on Monday as the surface low lifts northeast across the area and the main upper-level low remains becomes anchored across the Upper Great Lakes. If the pressure gradient can maintain some of its strength across Upper Michigan, Monday could also be a breezy day. Given the cool and cloudy conditions expected, did bump afternoon high temperatures for Monday down a bit. This cool and cloudy weather will continue through Tuesday as a shortwave digs south across the Upper Mississippi River Valley and brings a reinforcing shot of cooler Canadian air. Given the lingering cloud cover and enhanced lift as vorticity maxes dig south across the area, we could see scattered rain showers linger through the day on Tuesday. No concerns for thunder through this time period as mid- level lapse rates only approaching 6.0-6.5C/km at best and the atmosphere remains stable. Through the day on Wednesday, skies are expected to finally clear from west to east, and precipitation chances will come to an end. The best chance for any additional precipitation during the day on Wednesday will be across south central and eastern portions of the area. As the main 850mb low slowly rotates about the Ohio River Valley, even though we will still be under a modified cooler airmass, the increasing insolation should allow temperatures to warm up into the mid/upper 50s across much of Upper Michigan. Thursday through Friday, as moist and warmer 850mb air pivot back northeast into the Upper Great Lakes, temperatures will warm back up to near normal for this time of year. Not expecting any precipitation as subsidence should be dominant with upper-level heights building across the region, allowing a narrow area of surface high pressure to impact Upper Michigan. Friday night through Saturday, as troughing continues to traverses and begins to eject out across the west, surface ridging will shift east of the region and a lee cyclone is progged to develop across the High Plains. As a result, low-level moisture will try to make a return to the Upper Great Lakes. There is some uncertainty among the medium range models in how regards to how quickly this moisture return will occur, with the GFS being the most robust this far north. Depending on how much moisture can get this far north, we could see the return of some thunderstorm activity to the region for Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 641 PM EDT SAT MAY 20 2017 Rain showers will lift north across the area as low pressure approaches. Conditions will fall to MVFR at all sites this evening as the rain becomes more widespread, and as rain begins to taper off overnight tonight conditions will lower to IFR. There may even be a period of LIFR conditions at KSAW late tonight in a moist upslope ese flow. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 413 PM EDT SAT MAY 20 2017 An increasing pres gradient ahead of low pressure lifting toward Lake Superior will result in strong winds up to 30 kts and a few gale force gusts to 35 knots. As the low pres passes into Ontario on Sun and drags a trough across Lake Superior, expect the winds to diminish and shift to the w-sw by Sun night. Winds under 20 kts should then be the rule on Mon into Wed as a relatively flat pres gradient dominates the Upper Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Ritzman AVIATION...07 MARINE...JLB
Area Forecast Discussion
National Weather Service Nashville TN
728 PM CDT Sat May 20 2017 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Will opt to continue to slowly clear counties from the watch from west to east. Over the past hour, strong storms have moved into the southern Cumberland Plateau with 40 to 50 mph wind gusts. Thus, will refrain from pulling the entire watch at this time. Otw, instability levels are on the downswing. Latest Hrrr data shows a continuation of showers and thunderstorms over our eastern third. Back to the west, a break is indicated before some redevelopment occurs just west of the TN river toward 10z. For the update, will lower pops some but not too much as the main frontal boundary will continue to reside to our west overnight, with an increase in proximity with time. No other changes at this time. Current dewpoints are very close to projected lows, so temps look ok. && .AVIATION... 00Z TAF DISCUSSION. Frontal boundary stretches from central MO southward through central AR. Pre frontal forcing exists in advance of the main boundary, and this has helped initiate the current convection across the mid state. Should see a bit of a break aft 08z as this current convection pulls east. Toward 12z, cigs and vsbys will be somewhat reduced. Showers will redevelop in the morning, with tstms again being possible by afternoon as the aforementioned main frontal boundary reaches our area. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......21 AVIATION........07
Area Forecast Discussion
National Weather Service Shreveport LA
1018 PM CDT Sat May 20 2017 .DISCUSSION... Sct convection continues this evening over portions of extreme Ern TX/NW LA, generally along a Nwd surging outflow bndry that is intersecting a weak and shallow cold front analyzed from near a HOT, to TXK, to just E of GGG, to JSO and CLL line as of 03Z. Moderate MLCapes of 1500-2000 J/KG remains over these areas, but storm intensity should continue to diminish as instability wanes overnight. The short term progs are all over the place with whether or not convection will continue or not, with the HRRR initializing best with the ongoing convection, and actually expands it E across much of N LA along/just ahead of our cold front overnight as the front drifts SE through the remainder of the area, exiting the region by/shortly after daybreak Sunday. The 00Z NAM is quite aggressive with convection exploding by 06Z but appears tied to feedback issues, but the latest water vapor imagery suggests a weak shortwave over Cntrl TX which is driving isolated convection development NW of LZZ, with this shortwave moving over the region late tonight/Sunday morning. Even as the shallow front slips SE overnight, the H850 trough will still lag the front a ways, and could still focus at least isolated to sct redevelopment mainly SE of the I-30 corridor of NE TX/SW AR as well as N LA. Have made some minor adjustments to pops tonight in the forecast update, mainly to lower pops slightly over NE TX and remove them over SE OK/adjacent SW AR N of the H850 trough. Did maintain mid chance pops over much of lower E TX/N LA for the ongoing convection, and potential for additional redevelopment late with the arrival of the Cntrl TX shortwave and outflow bndrys still building back N across SE TX near/W of LFK. Also raised min temps a bit overnight as well, as cold advection will be shallow, and the 02-03Z temps/dewpoints are not cooling as fast as earlier forecast closer to and N of the I-30 corridor. Zone update already out...grids will be available shortly. 15 && .PREV DISCUSSION... /issued 810 PM CDT Sat May 20 2017/ AVIATION... For the ArkLaTex, a weak cold front is nudging in across E TX, NW LA and S AR. KLFK on the worse end with recent svr tstm. Convection is going to linger S of I-20 due to fropa later. Overall, we had a busy morning and just have not fully recovered area wide limiting coverage, but some shwrs will be in and out of terminals overnight and amendments may be necessary for tstms. Sfc winds bcmg N. Climb is NW10KT, but quickly SW/W 20-50KT into flight levels. Otherwise this front will lift back soon with more convection into new week. /24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 67 80 62 75 / 40 30 20 50 MLU 68 81 63 75 / 40 40 20 50 DEQ 57 80 56 79 / 10 10 10 20 TXK 62 79 59 76 / 20 10 10 30 ELD 64 78 58 77 / 30 20 10 30 TYR 63 79 62 76 / 30 20 30 50 GGG 65 79 61 75 / 30 20 30 50 LFK 67 83 66 76 / 40 50 30 60 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 15
Area Forecast Discussion
National Weather Service San Angelo TX
703 PM CDT Sat May 20 2017 .AVIATION... /00Z TAFS/ VFR conditions will persist across the terminals through the evening hours. Stratus will develop across the southern terminals late tonight, with MVFR ceilings expected into the morning hours. Scattered showers and a few thunderstorms are expected to develop towards daybreak across the southern terminals and linger through much of the day. Thunder chances may increase by afternoon but due to coverage uncertainties, will only mention VCTS during the afternoon hours at this time. && .PREV DISCUSSION... /issued 347 PM CDT Sat May 20 2017/ SHORT TERM... (Tonight and Sunday) Moist air overrunning the cold front will likely allow the development of isolated to scattered showers south of Interstate 20 tonight and Sunday. Texas Tech WRF and HRRR indicate a few showers developing along the I-10 corridor late this evening, spreading north to the Concho Valley toward morning. An isolated severe thunderstorm is possible...Sunday afternoon and evening along and south of the I-10 corridor, where GFS MUCAPES range from 1000 to 1200 J/KG along with moderate 0-6 KM shear values of 35 to 40 KTS. An upper shortwave moving east across the Big Bend and northern Mexico will also increase the potential for storms Sunday afternoon, particularly in Crockett country. Lows tonight will range from lower/mid 50s in the Big Country where clear skies will mainly prevail, to upper 50s to lower 60s to the south where developing stratus will limit cooling. Temperatures will stay cooler Sunday. Highs Sunday will range from the upper 70s to lower 80s in the Big Country to lower/mid 70s farther south where stratus limits surface heating. LONG TERM... (Sunday Night through Saturday) Unsettled pattern continues into early next week. Low level moisture will surge northward Sunday Night and Monday as the front to the south dissipates. With abundant cloud cover, instability will be somewhat limited on Monday. Cap will be weaker as well however, so scattered showers and thunderstorms continues to look possible. Cold front will slide through West Central Texas late Monday Night into Tuesday morning, bringing a focus for additional showers and storms. Drier air mass follows the front, ending the precip chances for the remainder of the week. Cloud cover will keep temperatures down to around 80 degrees for Monday, with the front and more cloud cover keeping readings even a few degrees cooler for Tuesday. Warm up starts mid week however, with afternoon highs pushing towards the upper 80s on Thursday and then into the lower 90s for Friday. && .PRELIMINARY POINT TEMPS/POPS... Abilene 56 78 59 78 / 10 10 30 40 San Angelo 59 75 60 80 / 30 40 40 30 Junction 63 75 62 81 / 40 40 60 40 Brownwood 57 77 59 77 / 20 20 40 40 Sweetwater 55 77 58 78 / 5 10 20 40 Ozona 60 73 61 81 / 40 50 60 30 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ 99/99/24