Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/20/17

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1000 PM MDT Tue Sep 19 2017 .UPDATE... Issued at 955 PM MDT Tue Sep 19 2017 The dry cold front that race southward across the forecast area late this afternoon has already moved well south of the forecast area this evening. Winds will continue to weaken overnight with relative humidities steadily rising as temperatures fall to levels below average overnight. The higher mountains in Jackson and Larimer Counties could see some light snow overnight with a narrow band of baroclinicity straddling this area. Should see little to no accumulation up there. On Wednesday, still looks like it will not be as warm on Wednesday and winds will generally be lighter. Although south to southwest winds will increase in speed during the afternoon on the west slope and eastern plains. Fireweather highlights are not anticipated for Wednesday but the wildland fire danger will remain elevated due to low relative humidities and dry fuels. && .SHORT TERM...(This evening through Wednesday) Issued at 315 PM MDT Tue Sep 19 2017 A strong southwest/westerly flow aloft will be over the region with the mid level trough axis shifting to the north and east overnight. Weak mid level qg ascent will be around through this evening, with moderate mid level qg descent overnight. Any precipitation will be light through early this evening and confined to the northern border. Strongest winds this afternoon ahead of a cold front that will push across the cwa from the northwest this evening. Strongest winds so far today in the mountains, high valleys foothills and Palmer Divide. Still waiting for stronger winds to mix out across the the northeast plains. Reference the fire weather discussion below. The cold front is already moving through KCYS at this time so fropa at Denver will be much sooner, by 01z. Much faster than what the HRRR was advertising. On Wednesday, a dry and strong west/southwesterly flow will remain over CO with weak mid level qg descent over the region. At 700 mb, temperatures around 12c for Denver dropping to around 9C on Wednesday. Some relief, albeit brief, with highs near 80 in Denver. .LONG TERM...(Wednesday night through Tuesday) Issued at 315 PM MDT Tue Sep 19 2017 A longwave trough will slowly shift east across western North American through the later part of the week. Southwest flow aloft will increase through Friday when a 110 knot jet will be over the state. Expect very warm conditions Thursday with highs in the mid to upper 80s across Colorado. Gusty southerly winds will increase the fire danger over the area. On Friday, a surface low pressure trough is expected to form over northeast Colorado. Cooler air will be pulled in from the north. Meanwhile southerly flow south of it will keep warm temperatures in place. Biggest questions is where this will set up. Cold air usually wins out and advances farther south than the models show. Will trend the forecast this direction with cool temperatures north and warm temperatures south. Expect isolated to scattered showers and storms Friday afternoon and evening. Best chance for precipitation will be over northern and eastern areas where the best moisture will be located. The surface trough shifts to the south and east of the area Friday night. Cool north to northeast surface winds will prevail behind it on Saturday. Highs will be below normal Saturday with readings mainly in the 60s across northeast Colorado. Lift from a short wave trough in the southwest flow aloft is expected to increase moisture and precipitation over the area Saturday night and Sunday. Will have the highest pops during this time frame. If skies remain cloudy all day Sunday, highs will likely stay in the 50s over northeast Colorado. For Monday and Tuesday, models are not in agreement on where the upper level trough goes. The GFS keeps the trough centered over the Great Basin while it weakens. The ECMWF is progressive and lifts the trough to the northern plains by Tuesday. Either way the area will be under some sort of troughiness. Therefore, will keep temperatures on the cool side will low pops. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 955 PM MDT Tue Sep 19 2017 VFR conditions likely for the next 24 hours. Light south- southeast winds overnight will generally remain southerly during the day Wednesday. However, wind speeds are expected to increase in the afternoon with possible gusts to around 25 kts on the south and east sides of the metro area. && .FIRE WEATHER... Issued at 315 PM MDT Tue Sep 19 2017 Will continue with the Red Flag Warning at least through this aftn. The cold front will move into the Denver area by 01z which should allow for temperature and rh recovery to occur a little faster this evening. Strongest winds over the higher terrain today. Slower to mix out across the plains but relative humidities have dropped into the single digits. No fire weather highlights are anticipated on Wednesday but the fire danger will remain elevated due to the dry conditions. Less wind, cooler temperatures and slightly better relative humidities expected Wednesday afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Baker SHORT TERM...Cooper LONG TERM...Meier AVIATION...Baker FIRE WEATHER...Cooper
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
712 PM CDT Tue Sep 19 2017 .UPDATE.../Brief evening PoPs added to I-35 corridor/ Radar indications reflect some light showers approaching the metro areas although the potential for lightning is on the decrease. Some isolated pockets of thunderstorm chances were left in based on the current radar and the latest HRRR output. The rapid refresh initialization looks more reasonable in the latest runs and will follow the trends to end mentionable rain chances at around 03Z. && .PREV DISCUSSION... /ISSUED 659 PM CDT Tue Sep 19 2017/ AVIATION.../00Z_TAFS/ A pair of thunderstorm complexes in the northern Hill Country and the Rio Grande Plains should miss the I-35 TAF sites aside from possibly light rain at SAT/SSF over the next few hours. Additional thunderstorm development is not expected due to the loss of daytime heating and a stable layer at 10 kft. VFR conditions with southeast 10-15 knot winds are expected this evening at all TAF sites. MVFR ceilings should develop once again at the I-35 TAF sites between 7-8Z, but the onset may be a bit delayed depending on much the complex of storms over the Rio Grande Plains disrupts low-level onshore flow. VFR conditions should return by 16-17Z at all sites. PREV DISCUSSION... /ISSUED 422 PM CDT Tue Sep 19 2017/ UPDATE... /Extended PoPs east thru this evening/ Rapid refresh models are performing poorly in the handling of a shortwave over West Central TX. Will apply a blend of the rapid refresh and the gfs to extend PoPs eastward to just west of I-35. All models indicate decreased rain chances by late tonight. PREV DISCUSSION... /ISSUED 314 PM CDT Tue Sep 19 2017/ SHORT TERM (Tonight through Wednesday Night)... A line of showers and storms that developed west of the Rio Grande has managed to remain intact and move into the western portion of Val Verde county as of early this afternoon. So far, the 17Z run of the HRRR seems to have a good handle on the convection when compared to current radar data. Given the above, we have increased rain chances along the Rio Grande through this afternoon. Some strong wind gusts are possible with the stronger storms, especially across Val Verde county. In addition, another area of convection is beginning to develop across the southern Edwards Plateau, including Edwards county. The HRRR is a little less aggressive with this convection, but given ongoing trends, we did opt to show a low chance for showers and storms for the afternoon hours. We will need to monitor convective trends over west central Texas this evening as some of the models show a complex of thunderstorms developing this evening. For now, we will keep a low chance for showers and storms for this evening for areas generally along and north of a Del Rio to Rocksprings to Burnet line. If convection does materialize, parts of the western Hill Country (Llano and Burnet counties) may see some showers and storms early Wednesday morning. Confidence in this scenario is low at this time and for now we will not mention in the latest forecast. Elsewhere, some convection is ongoing east of the I-35 corridor along a Cuero to Giddings line. The convection east of I-35 will likely decrease by early evening with the loss of daytime heating. Any rain chances on Wednesday will again likely remain confined to areas east of I-35. Some isolated activity is also possible across far western Val Verde county. We expect little change in temperatures through midweek, with highs in the 90s and lows in the 70s. LONG TERM (Thursday through Tuesday)... Some weak mid-level shortwave energy moving in from the west on Thursday should help to generate some isolated to scattered convection across south central Texas. Rain chances should still be favored along and east of I-35 where deeper moisture will reside and we`ll continue to mention 30-40% chances here, with 20% elsewhere. The forecast for the remainder of the work week into the upcoming weekend should result in continued isolated afternoon showers and thunderstorms, mainly along and east of the I-35 corridor. In addition, we expect above normal temperatures to continue given mid and upper level ridging along with southerly flow in the low-levels. The forecast for the early portion of next week could become a little more active as a longwave trough to our west may ease into the western half of Texas. This upper trough should help to weaken the persistent upper ridging and allow a more active southwest flow aloft to spread into the region. For now, we will only mention low chances for rainfall as the medium range deterministic models diverge on handling this upper trough beginning late Monday into Tuesday. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 75 94 76 92 74 / 20 - - 20 10 Austin Bergstrom Intl Airport 75 94 75 91 72 / 20 - - 20 10 New Braunfels Muni Airport 74 95 75 93 72 / 20 10 10 20 10 Burnet Muni Airport 73 92 74 90 72 / 40 - 0 20 10 Del Rio Intl Airport 79 99 77 97 75 / 10 10 10 20 10 Georgetown Muni Airport 76 94 76 91 73 / 20 - 0 20 10 Hondo Muni Airport 76 99 76 96 74 / 30 - 10 20 10 San Marcos Muni Airport 74 94 75 92 72 / 20 10 10 20 10 La Grange - Fayette Regional 76 93 75 91 73 / 20 20 10 40 10 San Antonio Intl Airport 77 95 77 93 75 / 20 - 10 20 10 Stinson Muni Airport 76 96 77 94 75 / 20 - - 20 10 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...LH Synoptic/Grids...Oaks Public Service/Data Collection...YB
Area Forecast Discussion
National Weather Service Peachtree City GA
1103 PM EDT Tue Sep 19 2017 .UPDATE... Light showers and a few thunderstorms continue just across the far west central CWA boundary in Alabama this evening. Have gone ahead and continued mention of slight chance thunder through 06z. The weakening/diminishing trend is expected to continue as the precip area moves into the state. Otherwise, have made only minor changes to hourly trends, and the forecast appears to be on track. 31 && .PREV DISCUSSION... /Issued 732 PM EDT Tue Sep 19 2017/ /Issued 315 PM EDT Tue Sep 19 2017/ SHORT TERM /Tonight through Wednesday Night/... Convection to the west has been more plentiful in coverage than earlier models might have projected but mesoanalysis indicates plenty of reasons why. Mixed layer CAPE values over portions of Alabama are in excess of 2000 J/KG and sfc based over 3000 J/KG. With precipitable water over 1.50 inches, this along with the robust energy has been more than enough to warrant the enhanced coverage to our west. The big question remains how much of this activity holds together for the local area. Although no where near that much energy resides currently over the western zones, RAP does bring some 1500 CAPE values in late this afternoon. Have therefore continued with the high end chance pops through this evening for NW corner but stopped short of likely based on HRRR models quick dissipation. Shortwave is a slow mover but should move across the northern sections during the overnight period with limited pop coverage. This would setup the Central zones as having the best chance for pops on Wed. Models show moisture pooling from CSG to MCN and points southward with PWs near 1.75 inches along with modest CAPE values of 1500 J/KG. Still some residual cool air aloft so cannot rule out some isolated strong storms during the afternoon hours. Deese /Issued 315 PM EDT Tue Sep 19 2017/ LONG TERM /Thursday through Tuesday/... Only slight changes have been made to the extended forecast. The ridge pattern positioned over the area is expected to have broken down by the beginning of the extended period and will be replaced by weak upper-level troughing. This trough pattern will contain multiple shortwaves embedded within. As a result of these upper- level impulses, isolated to scattered diurnally favored showers and thunderstorms can be expected in the area in the later parts of the week and into the weekend. The highest PoPs will be on Thursday and Friday afternoon, mainly in the 30 to 40 percent range. PoPs have been lowered on Friday from the previous forecast due to a lowered confidence in surface-based forcing. GFS/ECMWF/NAM/Canadian models all continue to keep any direct impact from Jose/Maria far to the east of the area. The official forecast from NHC reflects this as well. Maria is expected to force a drier and more stable air mass into the area on Sunday which will remain in place until Tuesday. This air mass will lead to more seasonal temperatures and humidity, along with lower PoPs, starting during the weekend and into the early parts of next week. 09/NListemaa AVIATION... 00Z Update... VFR expected through the period. Rain and a few embedded thunderstorms moving east toward the GA/AL border continue to dissipate into the state. At this time, have opted for VCSH at KCSG, but no precip mentioned elsewhere tonight. For tomorrow, isolated to scattered showers are expected generally after 18z, and have gone with VCSH for all TAF sites. W-NW winds will be light overnight, then increase to 4-6kt through the day. Slight visibility reductions to MVFR are possible for KCSG and KMCN overnight. //ATL Confidence...00Z Update... High on all elements. 31 && .PRELIMINARY POINT TEMPS/POPS... Athens 67 88 66 88 / 20 20 20 30 Atlanta 70 87 70 87 / 20 20 10 30 Blairsville 61 82 60 83 / 20 20 10 40 Cartersville 66 87 65 88 / 20 20 10 30 Columbus 71 90 71 90 / 50 20 20 40 Gainesville 68 86 67 85 / 20 20 10 30 Macon 68 90 69 89 / 20 20 20 40 Rome 66 88 66 88 / 20 20 10 30 Peachtree City 67 88 67 87 / 20 20 20 30 Vidalia 71 91 71 89 / 20 30 20 50 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...31 LONG TERM....41 AVIATION...31
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
858 PM CDT Tue Sep 19 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION... The afternoon convection has now dissipated and skies continue to clear out. Some high clouds may filter through the region overnight with some low clouds and patchy fog forming near dawn in isolated locations. No changes to forecast were needed for this update. /10/ Prior discussion below: Tonight through Wednesday... Latest RAP satellite imagery showed shortwave passing through the region. This combined with some cooling aloft and low level moisture had triggered scattered showers and some thunderstorms across the region. With 6-7c lapse rates we may see a few strong storms with some gusty winds for the remainder of the afternoon. Expect the shortwave to exit the region by early this evening. For early this evening the last of the showers will end across the east and southeast. For later tonight expecting another round of patchy fog prior to dawn which will lift by 14z. Another shortwave will approach from the west on Wednesday. Return flow ahead of this feature will trigger isolated to scattered showers and thunderstorms mainly during the afternoon. Once again midlevel lapse rates will be from 6-7C with weak flow. This could bring a few strong storms with some gusty winds during the afternoon. As far as temperatures are concern readings will continue to be above normal. Lows will be in the upper 60s to lower 70s. Highs will be in the lower 90s. Heat indices will range from the middle 90s to around 100./17/ Wednesday night through Tuesday... A warm summer like pattern will persist through the long term period with isolated to scattered diurnally driven afternoon showers and thunderstorms possible through at least this weekend. The period will start off with Jose forecast to be a tropical storm off the New England Coast, Hurricane Maria just to the northwest of Puerto Rico while ridging remains centered over the mid Mississippi River valley into the Midwest. A strong digging longwave trough over the western CONUS will help to amplify the ridging going into the weekend, which could lead to some degree of increased heat stress across the Delta. However, a weakness/upper level low is progged to retrograde beneath the ridge into the northern Gulf/ArkLaMiss, which would in turn keep lower heights over the CWA and help to keep heat issues in check. With that being said, max heat index values look to top out in the 100-103 degree range in a few locations which isn`t enough to warrant mention in the HWO/graphics at this time. In terms of rain chances, isolated to scattered afternoon showers and storms can be expected through at least this weekend before drier air wedges in from the east by late weekend/early next work week. Widespread severe weather is not expected but a few strong storms with isolated gusty winds cannot be ruled out primarily early in the period. Going into the early portion of next week, the ridging should break down as the longwave trough lifts through the Midwest and brings a cold front and a more fall like airmass towards the ArkLaMiss. /TW/ && .AVIATION... 00Z TAF discussion: Isold TSRA were noted in vcty of HBG at 2315Z. This activity wl dissipate by 20/01Z and VFR conds wl prevail areawide until 10Z. After 10z MVFR vsbys wl be psbl until 14Z. VFR conds wl prevail Wed but Isold to Sct TSRAs wl develop around the area Wed aftn and early evng. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 71 91 71 91 / 9 32 8 30 Meridian 70 91 70 90 / 11 35 10 31 Vicksburg 72 90 71 91 / 7 26 7 28 Hattiesburg 70 90 70 90 / 12 42 21 38 Natchez 72 90 71 90 / 8 28 8 31 Greenville 72 92 71 92 / 6 21 8 23 Greenwood 72 91 71 92 / 6 27 9 24 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
Area Forecast Discussion
National Weather Service Miami FL
811 PM EDT Tue Sep 19 2017 .UPDATE... Strong sea breeze interactions and a slight increase in atmospheric moisture has led to scattered showers with isolated thunderstorms over the peninsula. These slow moving, or even stationary, storms have produced rather impressive accumulations in some areas across the east coast metro region. Minor street flooding was already reported this evening in Hialeah. In the update, bumped up PoPs and coverage to reflect the ongoing activity. The HRRR shows these showers maintaining over the next several hours. Otherwise, the rest of the forecast appeared on track. && .PREV DISCUSSION... /issued 733 PM EDT Tue Sep 19 2017/ AVIATION... Showers and thunderstorms along the east coast metro area should begin to fade after sunset. Until then, have TS mentioned at most of the TAF sites for the next couple of hours. Conditions are forecast to improve tonight. Tomorrow should see another round of convection, but uncertainty is too high to mention anything in the TAFs ATTM. Otherwise, VFR conditions through the TAF period, with the exception of brief IFR under heavy shra possible. PREV DISCUSSION... /issued 436 PM EDT Tue Sep 19 2017/ DISCUSSION... Latest visible satellite imagery shows scattered diurnally driven fair weather cu dominating over most of the peninsula. Enhanced lift along a weak boundary over Palm Beach County was creating towering cu and a few showers in the northeast portion of the CWA. An isolated thunderstorm will be possible through this evening, but with 500 mb warmer than -6.0 C, not anticipating any strong convection. Otherwise, rather benign weather continues across south Florida. Maximum temperatures are topping off in the upper 80s along the east coast metro region and lower 90s for the interior. Relatively dry air continues to advect in behind Hurricane Jose and will do so through the night. Short range models, including the HRRR and WRF, show shower activity diminishing overnight, with the loss of diurnal heating. Wednesday through Sunday: As Hurricane Jose weakens over the next several days, there will be less of an influence on our area. Mid range models prog a large high pressure ridge to build over the eastern CONUS in its wake. Thus, surface high pressure to the north will maintain easterly flow over the Florida peninsula. Various surges of moisture from the over Atlantic will help to generate isolated showers and thunderstorms. Coverage will be greatest for interior during the afternoons, then transition to the east coast metro at night. Maximum temperatures will be around average for this time of year with upper 80s along the coast and around 90 inland. Through the period, Hurricane Maria is forecast to move northwest from Puerto Rico, then north of the Turks and Caicos. Thus, no direct impacts from the Hurricane are anticipated for our region. While the track of Maria is expected to remain to our east, continue to keep a close eye on the forecast over the next several days. In the meantime, it is always a good idea to review hurricane plans and to restock any items used during Hurricane Irma as we continue to remain in the middle of hurricane season. MARINE... Long period swell from distant Hurricane Jose will keep cautionary conditions over the waters off Palm Beach County into midweek. Conditions will briefly improve late week as Jose moves farther from the area and high pressure builds back into the region with increasing east-northeast flow. BEACH FORECAST... Long period northeasterly swell from the distant Hurricane Jose will continue to filter through the local Atlantic waters. A high risk of rip currents will continue for all the Atlantic beaches this evening, and likely remain moderate to high into late week. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 76 90 76 89 / 40 30 30 40 Fort Lauderdale 78 91 78 90 / 30 20 20 30 Miami 77 91 77 91 / 20 10 10 30 Naples 75 91 75 91 / 20 20 20 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Wednesday evening for FLZ168-172- 173. AM...None. GM...None. && UPDATE...27/JT DISCUSSION...27/JT MARINE...27/JT AVIATION...13 BEACH FORECAST...27/JT
Area Forecast Discussion
National Weather Service Omaha/Valley NE
556 PM CDT Tue Sep 19 2017 .SHORT TERM...(Tonight through Friday) Issued at 329 PM CDT Tue Sep 19 2017 Midsummer-like conditions have returned to the area under strong warm and moist air advection in the lower levels. Subjective 12Z upper-air analysis indicates an upper-level trough digging into the western US and ridging in the east, with an embedded shortwave over IN/IL. 850mb dewpoints of 12C+ had pushed into NE/western IA by 12Z on rather strong 850mb southerly winds. Surface lows at 20Z were centered in central SD and northeast CO, with a cold front between. Main forecast concern is whether storms will brush northeast NE this evening and tonight, then chances again on Wednesday evening in southwest Iowa. For tonight, 18Z soundings from both OMA and ABR indicate substantial cap, reinforcing RAP mesoanalysis of the cap persisting in NE. Where cap has eroded in central SD, convective development is likely later this afternoon into this evening, with convection persisting tonight. Should any development occur in or move into northeast NE, abundant low-level and deep-layer shear would support potential for storms to become severe, with large hail and damaging winds the main risk, as well as a non-zero risk for tornado development. Cold front will progress through the area tonight and Wednesday, bringing cooler temperatures. Additionally, shower/thunderstorm development is possible in southwest Iowa mainly in the evening as the front encounters a more unstable atmosphere toward the southeast, but the risk for stronger storms is likely to stay southeast and out of the area. Warmer temperatures will return quickly for Thursday and Friday under return flow, along with a moistening low- to mid-level airmass under renewed warm/moist air advection. .LONG TERM...(Friday night through Tuesday) Issued at 329 PM CDT Tue Sep 19 2017 Pattern shift continues to show itself for the weekend into next week, with an upper-level low digging into the Rockies/western US and ridging over the eastern US. A slow-moving front through the Plains will provide focus for prolonged moderate to heavy rainfall. Timing continues to slow in the model guidance, and have slowed onset of precipitation further today. Have considerable uncertainty regarding convective side of the precipitation. Convective instability looks likely, especially in the earlier part of the prolonged event, but widespread coverage of showers and storms in September could quickly erode that instability and leave the rest of the weekend mainly rainy. Have kept thunder in the forecast for now, but think it is likely that later in the weekend and into next week, the event would be more rain than thunder. Rainfall could persist over several days, with moderate to heavy accumulations. Current ground conditions could take some rain, but urban areas and at least flashier creeks and streams could be susceptible to some flooding, especially if rainfall rates are on the higher side. In short, it is a potentially wet weekend into early week, but the details are still unclear. At the very least, areas that are under clouds and rain will be on the cool side, while those areas that stay ahead of the rain Friday and Saturday will still be able to warm up above normal. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 555 PM CDT Tue Sep 19 2017 A surface cold front from the central Dakotas to western NE as of early evening will advance southeast through the mid-MO Valley overnight with gusty south winds shifting to the northwest. The presence of a 50-60+ kt LLJ will result in LLWS criteria being exceeded at all three TAF sites through much of the overnight period. Otherwise, VFR conditions will prevail with passing high- level clouds. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Mayes LONG TERM...Mayes AVIATION...Mead
Area Forecast Discussion
National Weather Service San Angelo TX
657 PM CDT Tue Sep 19 2017 .AVIATION... /00Z TAFS/ VFR conditions expected across the terminals the next 24 hours. Scattered convection that affected KJCT and KBBD earlier this afternoon is now east of the terminals and no additional development is expected this evening. Could see some stratus develop near KJCT and KSOA around daybreak but most of this should be south of the terminals and will only include a scattered group for low clouds at this time. Expect south winds through the period, with gusts to around 20 knots on Wednesday. && .PREV DISCUSSION... /issued 532 PM CDT Tue Sep 19 2017/ DISCUSSION... Sent out a quick update to increase PoPs across the Heartland and northwest Hill Country where convection is ongoing. This activity is forecast to slowly move east into early this evening, before dissipating or moving east of the forecast area by mid evening. Although isolated showers and thunderstorms will be possible to our west along the dryline, the HRRR is showing very little development late this afternoon and evening. This seems reasonable as CAPE values are generally below 1000 J/KG and very little towering cumulus is evident on satellite. For now, 20 PoPs were kept across our western counties. Otherwise, no other changes are needed at this time. PREV DISCUSSION... /issued 345 PM CDT Tue Sep 19 2017/ SHORT TERM... (Tonight through Wednesday) Currently, we have scattered showers and thunderstorms east of a line from Abilene, to Menard, to Sonora. None of these storms are severe yet, but with MLCAPE values of up to 2500+ J/kg across our CWA, some of these storm could become marginally severe with wind gusts over 60 mph, and large hail. Additional thunderstorms are expected to develop to our west along a tightening dryline to our west. The later development will be moving into the same environment as these current storms, so will also have a chance for becoming severe due to large hail and wind gusts of 60 mph or greater. Should thunderstorms develop to our west, an MCS could form in our western CWA, and travel south/southeast into the Hill Country with a good LLJ aiding in sustaining thunderstorm development. Expect that most of the thunderstorm activity will end around midnight or shortly after. Expect lows tonight in the low 70s for most areas. On Wednesday, expect drier conditions over all, with continued very hot temperatures in the mid to upper 90s. LONG TERM... (Wednesday night through Tuesday) As an upper level trough deepens over the west coast, west-central Texas will be on the eastern fringes of southwesterly flow aloft. However, until the upper level trough moves towards the area late in the weekend/early next week, we will remain mostly dry as upper level high pressure centered near the Great Lakes ridges down into the region. Although a couple of diurnal storms cannot be ruled completely out, most areas should stay dry. As the upper level trough and associated cold front approach the region next week, rain chances will increase. As can be expected this far out, there are some models differences in timing/strength, but overall it appears that a decent chance of rain will impact the region at the end of the long term period. Temps will continue to be above normal, generally in the upper 80s to lower 90s. && .PRELIMINARY POINT TEMPS/POPS... Abilene 75 99 73 94 / 30 5 20 20 San Angelo 74 99 74 94 / 20 10 20 20 Junction 74 96 73 93 / 20 5 20 20 Brownwood 73 97 73 93 / 30 10 20 10 Sweetwater 74 97 73 93 / 20 10 20 20 Ozona 72 95 71 91 / 20 10 20 20 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ 99/99/24
Area Forecast Discussion
National Weather Service Tallahassee FL
900 PM EDT Tue Sep 19 2017 .UPDATE... Rather than diminishing at sunset, as one would expect in late summer, this evening`s showers and thunderstorms have become stronger and more numerous across south AL, where an outflow boundary has developed. This mesoscale feature separates a pool of relatively cool air and higher pressure to its north (across central AL) from a warm, moist airmass to its south (across our forecast area). Additionally, based on the 8 pm EDT Tallahassee RAOB, the airmass across our region has moistened and destabilized considerably. We added evening PoPs for much our forecast area (through 2 am) based on the expectation that at least scattered deep moist convection may continue to be sustained along the slowly- advancing boundary, which the recent RAP runs has moving southeastward. Our PoP forecast is somewhat based on the latest HRRR runs, except we had to extend the higher PoPs farther south to account for the HRRR`s incorrect storm initialization. && .AVIATION [Through 00Z Thursday]... We will update the KDHN TAF to account for a greater potential for TSRA early tonight. Otherwise our previous thinking holds: We expect mainly VFR conditions through Wednesday. As deep layer moisture increases Wednesday, we expect more SHRA/TSRA than what we`ve had recently, especially across the FL Panhandle. Scattered to numerous TSRA will develop along the sea breeze front Wednesday afternoon, affecting KECP and KTLH at times. Elsewhere TSRA will be isolated, and have not been forecast at the other terminals in this TAF package. && .PREV DISCUSSION [715 PM EDT]... .NEAR TERM [Through Tonight]... Isolated to scattered showers will diminish with the loss of daytime heating this evening, giving way to partly cloudy skies and continued muggy conditions. Given moist boundary layer conditions, light patchy fog is not out of the question across portions of the region, particularly in locales that see rainfall this afternoon. Overnight lows in the low 70s are expected across the region tonight. .SHORT TERM [Wednesday Through Thursday Night]... A train of southern stream shortwaves will come crashing into the Southeast Wednesday and Thursday. These waves will eventually consolidate as upper-level winds become north-easterly when broad low pressure forms over the Mid-Atlantic and Northeast influenced by Jose and a northern stream trough. A resultant surface trough is likely to form across the Southeast and force scattered convection each afternoon. PoPs will generally hover around 40%, with highs around 90 degrees. .LONG TERM [Friday Through Tuesday]... While the consolidating shortwave will remain trapped over the Southeast by Maria, deep-layer dry air will be funneling into the region from the north/northeast. Thus, PoPs will remain rather low beginning this weekend, with highs in the upper 80s. .MARINE... Light winds and low seas will prevail through the remainder of the week. By the weekend, easterly flow could result in some nocturnal wind surges at or above 15 knots. .FIRE WEATHER... Low dispersion values below 20 in the afternoon expected Wednesday and Thursday afternoons. Patchy fog is possible in the early morning hours. .HYDROLOGY... Average rainfall totals over the next several days are expected to be less than a half of an inch. Area river levels are continuing to fall across much of the region, and have crested near or in action stage across the Suwannee. Thus, there are no flooding concerns over the next several days. .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 72 90 71 89 71 / 20 40 20 40 20 Panama City 76 86 74 86 74 / 20 40 20 40 20 Dothan 71 89 71 90 70 / 50 40 20 40 20 Albany 71 90 71 90 70 / 40 20 20 40 20 Valdosta 70 89 71 88 70 / 20 20 20 40 20 Cross City 69 91 70 89 70 / 10 10 10 20 20 Apalachicola 74 87 74 87 74 / 10 30 10 40 20 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ UPDATE...Fournier NEAR TERM...Pullin SHORT TERM...Harrigan LONG TERM...Harrigan AVIATION...Fournier MARINE...Harrigan FIRE WEATHER...McD HYDROLOGY...Harrigan