Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/02/18


Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
835 PM CDT Sat Sep 1 2018 .UPDATE... Issued at 826 PM CDT Sat Sep 1 2018 Not anticipating any major changes this evening. Last few HRRR runs are adamant that an MCS will form around the Missouri valley, and then quickly move east overnight. Moderate LLJ should usher in more moisture and instability to the CWA overnight, leading to the potential for isolated svr wind/hail reports. Temperatures appear okay for now. && .SHORT TERM...(This Evening through Sunday Afternoon) Issued at 329 PM CDT Sat Sep 1 2018 Light showers/sprinkles finally dissipating late this afternoon near the James Valley as they encounter little to no instability. Otherwise, all of the operational models and high-res models show a couple short wave troughs coming over the region from the west tonight into early Sunday. The models show instability will be drawn back north tonight supplying these waves with energy and moisture for scattered showers/storms to develop. The deep layer wind shear will be marginal with 1000-2000 j/kg cape possibly resulting in some severe storms tonight. We have a marginal risk for severe weather for most of the cwa tonight. Have in mainly chance pops for tonight ending in the southeast cwa on Sunday morning. Surface high pressure and cooler and drier air will push in through the day on Sunday behind a surface cold front coming through our cwa tonight. .LONG TERM...(Sunday Evening through Saturday) Issued at 328 PM CDT Sat Sep 1 2018 Initially upper pattern shows generally zonal flow across the northern tier of the country, but becomes slightly more amplified through the day Monday, with ridging in the east and troughing in the west. Flow aloft becomes southwesterly in response, with a wave moving from western to central Canada, drawing in remnants of monsoon moisture over the 4-corners region along with an influx from the Gulf of Mexico. This shows up in BUFKIT soundings as a mainly moist adiabatic profile for the southeast and south central CWA late Monday, with PWATS near 1.8 inches. Generally there is weak ascent from isentropic upglide however, and MUCAPE only around a few hundred j/kg. The main reason there is limited instability is that low level flow is east/southeasterly so Dewpoints are slow to respond and peak Tuesday. The eastern CWA will see some higher MLCAPE values Tuesday afternoon under a high PWAT environment, mainly across the east. Precipitation looks like a good bet, with Q-vectors hinting at some forcing aloft from a 70kt southern stream jet. The only caveats is that quite a bit of mid/high clouds will limited surface heating, and the 500mb wave is deflected northeast as the ridge east builds. Blended model guidance has broad 30-40 percent coverage west of the Coteau, where there is better opportunity for sunshine, with a front/inverted trough splayed across the CWA. A cooler Canadian airmass follows for Tuesday night with the core of coolest air overhead Wednesday, which will allow for some chilly readings Thursday morning (850mb temps down to +8 to +10C Wed PM), though track of the high center to our north may mean winds won`t completely decouple across the entire CWA. Looks like the latter half of the week will be dry too. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 630 PM CDT Sat Sep 1 2018 VFR skies/vsbys are expected at all terminals through tonight. Isold/sct storms are possible, and could provide for brief periods of MVFR/IFR conditions during rainfall. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TDK SHORT TERM...Mohr LONG TERM...Connelly AVIATION...TDK
Area Forecast Discussion
National Weather Service Albany NY
950 PM EDT Sat Sep 1 2018 .SYNOPSIS... High pressure off New England will control our weather through Monday. Humidity levels increase on Sunday with a warm front triggering an isolated shower or thunderstorm, mainly west of the Hudson River Valley. Heat and humidity increases on Labor Day with hazy, hot and humid weather. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... As of 730 PM EDT, still quite a bit of mid level clouds across the eastern Catskills, Litchfield County CT into southeast Berkshire County MA, and across the SE Adirondacks into the Lake George/Saratoga region and northern Bennington County, VT. 00Z/ALY sounding suggests moisture trapped beneath strong inversion around 825 MB resulting in these clouds. Latest RAP13 and HRRR suggest these clouds slowly mix out later this evening, mostly after midnight as as upper ridging slowly amplifies and strengthens in the eastern U.S. However, some patchy clouds could linger through daybreak across the SE Catskills. In addition, some lower clouds may develop and/or expand northward up the Hudson River Valley after 08Z/Sun. The partial clearing through the night will make for a slow drop in temperatures this evening until the better clearing occurs after midnight. With light to calm winds and some radiational cooling, temperatures will fall into the lower to mid 60s in most areas, but 50s in higher terrain across portions of the Adirondacks, and perhaps pockets of the Berkshires, Taconics and southern VT where breaks in the clouds persist longest. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... There are questions as to how much capping there will be over our region with the upper ridging becoming so strong. Some upper energy tracks north of the U.S./Canadian border Sunday through Monday with the southern periphery of steadier boundary layer winds tracking through northern NY. Otherwise, there is little to no low level forcing to trigger or sustain any convection that could develop near and north of the Great Lakes. Convective debris and mid/high clouds are indicated in sources of guidance over much of our region along with some isolated to scattered convection tracking into the western Mohawk Valley, Schoharie Valley and southern Adirondacks Sunday. However, the strong upper ridging implies any convection should weaken before it reaches eastern NY and western New England. There will be a diffuse warm front and leading edge of the higher boundary layer temperatures and surface dew points later Sunday and Sunday night. So indicating isolated showers and storms associated with the warm front. With the warm front north and east of the region Monday, very little if any low level forcing outside of any lake breeze boundaries or a pre frontal wind shift well ahead of a weak backdoor cold front to the north. Instability looks impressive Monday when low level and boundary layer flow turns southwest and midlevel lapse rates steepen. The weak backdoor cold front could just scrape northern areas Monday night through Tuesday but may be more of a wind shift with a mix of high clouds rather than any sort of cool down. Isolated to scattered thunderstorms are possible in some areas Monday if a lake breeze or pre frontal surface trough can develop and depending on how capped we are with the strong upper ridging. Boundary layer temperatures drop just a little and boundary layer winds turn to the west and northwest by Tuesday. Still, sources of guidance suggest the surface dew points fall a little from the Mohawk Valley and southern VT and points north for Tuesday. So, the hottest weather and the most dangerous heat indices looks like Monday, although the mid Hudson Valley, parts of the southern Berkshires and NW CT could see dangerous heat both Monday and Tuesday. So, a mix of clouds and sun Sunday with isolated to scattered afternoon and evening showers and thunderstorms along the diffuse warm front. Highs in the upper 70s to lower 80s with a few mid 80s in areas that cloud see more sun and a bit cooler in higher terrain. More sun than clouds Monday with isolated to scattered late afternoon storms and southwest downslope flow, in the upper 80s to lower 90s but cooler in higher terrain. Heat indices in the Hudson and Mohawk Valleys into NW CT in the mid 90s to around 100. Intervals of clouds and sun Tuesday with highs in the 80s to around 90 and heat indices reaching the mid to upper 90s in the mid Hudson Valley to parts of the southern Berkshires and NW CT. So, Heat Advisories are possible in some areas Monday and Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... An early hint of fall is in store, but we will have to get through a hot mid-week period before it comes. A frontal boundary will become stationary along the Quebec-New York border Tuesday night. Rather calm wind conditions will result in a gradual increase in humidity with continued "hot for September" temperatures until showers and a cold front from the north break the pattern, and a strong dome of high pressure slides east across southern Canada, then dips into northern New England by the end of the week. Thusly, there`ll be scattered showers Thursday into Friday, with a gradual north to south cessation. High temperatures on Wednesday ranging from the mid and upper 70s in the high peaks...to around 90 degrees down the Hudson Valley will be dramatically lower by weeks end...from around 60 degrees in the high peaks to mostly the lower 70s in the valleys on Saturday. The changes in overnight lows will be less impressive, with overnight lows from the mid 60s to lower 70s Tuesday and Wednesday nights becoming from lows from around 50 degrees to the lower 60s by Friday night. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Mainly VFR conditions are expected through this evening, with areas of mid level clouds prevailing with bases 6000-8000 FT AGL. After midnight, areas of MVFR stratus are expected to develop, with best chances for MVFR Cigs expected between roughly 08Z- 14Z/Sun. There is a slight chance of embedded IFR Cigs around 12Z, but at this time, have kept Cigs low end MVFR. If breaks in the clouds persist long enough, some patchy ground fog could develop at KGFL at times, leading to intermittent MVFR/IFR Vsbys. This possibility may be greatest before midnight, as mid level clouds and some stratus develops thereafter. MVFR Cigs should slowly become VFR by midday Sunday. Scattered showers/isolated thunderstorms may approach KGFL and KALB from the west toward 00Z/Mon. Have indicated chance for showers during this time with a Prob30 group in TAFs at these locations. Winds will be from the southeast to south at 5-10 KT overnight, and may increase at KALB with some gusts of 15-18 KT possible. On Sunday, winds should be south to southwest at 8-12 KT. Outlook... Sunday Night: Low Operational Impact. Isolated SHRA. Labor Day: Low Operational Impact. Isolated SHRA...TSRA. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Low Operational Impact. Isolated SHRA...TSRA. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Low Operational Impact. Slight Chance of SHRA...TSRA. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. && .FIRE WEATHER... High pressure off New England will control our weather through Monday. Humidity levels increase on Sunday with a warm front triggering an isolated shower or thunderstorm, mainly west of the Hudson River Valley. Heat and humidity increases on Labor Day with hazy, hot and humid weather. The RH values will be close to 100 percent tonight and Sunday night with dew and patchy fog. The minimum RH values will only lower to 60 to 75 percent Sunday afternoon and 50 to 60 percent Monday afternoon. The winds will be light to calm tonight and Sunday night. Expect southerly winds at 5 to 15 mph on Sunday and southwest at around 15 mph Monday. && .HYDROLOGY... No hydrologic problems are anticipated through the holiday weekend into the mid week on the main stem rivers. High pressure will allow for mainly dry weather through Sunday, with just a stray light shower or thunderstorm possible, mainly west of the Hudson River Valley. There may be slightly more coverage of showers or thunderstorms for Monday into Tuesday, but rainfall amounts will be highly variable and basin average amounts are not expected to be excessive with the recent drier weather. As a result, river and stream levels will either hold steady or slowly fall through the holiday weekend into the mid week. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...NAS NEAR TERM...KL/NAS SHORT TERM...NAS LONG TERM...ELH AVIATION...KL FIRE WEATHER...NAS HYDROLOGY...NAS
Area Forecast Discussion
National Weather Service La Crosse WI
647 PM CDT Sat Sep 1 2018 .SHORT TERM...(This evening through Sunday night) Issued at 305 PM CDT Sat Sep 1 2018 Surface analysis early this afternoon shows a boundary extending from north central Iowa southeast into eastern Iowa along the Interstate 80 corridor. Another boundary extends from northeast Minnesota into western Iowa. Dew points are pooling along and south of the Iowa boundary with lower to middle 70s common. Both of these boundaries look like they will be active with showers and storms along them. A relative lull in the activity for the rest of the afternoon into the evening before things start to crank back up. A short wave trough coming out of eastern Colorado/Kansas this afternoon will move northeast across the region overnight before exiting off to the northeast late Sunday morning. As the wave moves northeast, the low level jet will get going but both the 01.12Z NAM and several runs of the RAP suggest this may not occur until the overnight hours. Once it does get going, it should be focused on the Iowa boundary with showers and storms expected to develop along and to the north of the boundary. Unlike past events, the low level jet does not look like it will maintain its strength for the entire night with rapid weakening shown after 02.09Z. This may help to keep the overall intensity of the convection lower and possibly with some lower rain rates. Once the low level jet weakens as the short wave trough moves off, the moisture transport axis then look to reorient itself along and ahead of the boundary coming in from Minnesota. With the upper level flow remaining southwest, there could be several weak short wave troughs embedded in this flow to interact with the front and moisture transport. Expecting at least scattered convection if not broken coverage for most of the day as this boundary works slowly to the southeast into the area. The boundary should continue to sink through the area Sunday night with a gradual push of the higher rain chances to the southern sections of the forecast area. .LONG TERM...(Sunday night through Saturday) Issued at 305 PM CDT Sat Sep 1 2018 An active pattern will continue through at least the first half of the week with bouts of showers/storms and heavy rainfall/flood concerns. As has been messaged for the past several days, little change in the overall synoptic regime will take place for several days. From a big picture perspective, a transition to a more southwest flow pattern will take place over the area in response to broad upper troughing progressing into the northern Rockies while a strong upper ridge persists over the Mid-Atlantic. Abundant, anomalous moisture will reside across the area with pwats approaching 2 inches. As weak upper waves move the flow and interact with a surface boundary whose placement likely will be impacted by daily convective trends, expect periodic chances of showers/storms. Models generally try to lift the boundary north through the area on Mon night/Tue ahead of the approaching upper trough, but confidence is low on how the surface pattern will resolve itself given the impacts of clouds/convection. As a result, placement of daily showers/storms remains somewhat uncertain. However, each round of showers/storms will be capable of heavy rainfall, which could exacerbate any ongoing flooding or lead to additional flooding. There is better agreement that the upper trough passing across southern Canada mid-week will drag a cold front through the area around Wednesday. Will have to watch to see how far/how fast the front progresses south of the area. It`s possible some convection could persist into Thursday especially across southwest WI, but confidence in these details is low. At this time it looks drier for Friday into the weekend. High temps will be in the 70s to low 80s early in the week, cooling slightly for a time late week behind the cold front. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 647 PM CDT Sat Sep 1 2018 Mainly VFR conditions out there at the moment, though we do see some "strands" of thicker stratocumulus clouds impacting RST and possibly LSE the next few hours, in which ceilings could briefly reach MVFR levels. Bigger story is the likely arrival of showers and storms later tonight, mainly between 08Z and 11Z for both LSE and RST, with confidence increasing enough to include a temporary mention of MVFR conditions in thunderstorms, though could be some brief IFR visibility depending on rainfall rates. As the main band of storms lifts north by 12Z, expecting to see additional scattered showers and thunderstorms for much of the remainder of the day on Sunday for LSE, while RST sees some early storm chances but with rain chances waning by afternoon as a weak cold front slides toward the area. Almost impossible at this point to nail down any specifics in terms of exact timing, so will carry a broad shower and vicinity thunder mention for much of the day. Winds will be mainly light (under 10 knots) tonight and Sunday, though there could be a few hour window of gusty south winds at either LSE or RST toward mid to late morning Sunday, depending on if any sunshine can be realized. && .HYDROLOGY... Issued at 305 PM CDT Sat Sep 1 2018 The set up for tonight is not quite as clear cut for heavy rain and possible flash flooding. The low level jet, while it looks like it will impinge on the boundary, does not look as strong or remain in place that long. Precipitable water values look to mainly be in the 1.5 to 1.75 inch range with both the RAP and NAM showing a narrow axis of higher values mainly right along and south of the boundary. Warm cloud depths are not as deep and generally look to be around 3.5 km. Still concerned this is enough to produce some locally heavy rains, just that the totals may be a little on the lower end. Also concerning that the ground across northeast Iowa into western Wisconsin south of Interstate 90 has been soaked by previous rains and does not have much storage capacity. 3 hour flash guidance for much of this area is 2 inches or less. Forecast rainfall amounts for tonight through Sunday are around an inch or less and not sure this will be enough to cause significant or widespread flooding problems. For now, plan to not issue a flash flood watch for tonight but not entirely comfortable with this given how saturated the ground already is. Later shifts may have to issue a watch on short notice if the rainfall looks heavier that currently expected. Flooding continues along the Kickapoo River and for now, levels continue to go down. See the latest flood statement for more details. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...04 LONG TERM...JM AVIATION...Lawrence HYDROLOGY...04
Area Forecast Discussion
National Weather Service Denver/Boulder CO
901 PM MDT Sat Sep 1 2018 .UPDATE... Issued at 831 PM MDT Sat Sep 1 2018 Majority of the convection has shifted into Nebraska as well as additional isolated activity over southern and eastern sections of the CWA. Weak upper low will continue to move across Central Colorado through Sunday morning with continued diminishing activity. Have lowered pops in most sections this evening with exception of areas noted above. Sunday should be drier with a more subsident airmass over Colorado. && .SHORT TERM...(This evening through Sunday) Issued at 1252 PM MDT Sat Sep 1 2018 This evening, a strong southwesterly flow aloft will be over the cwa ahead of a trough over the Great Basin. The latest HRRR keeps the greatest thunderstorm coverage over the Palmer Divide to the south and southeast of Denver. Strongest storms so far this afternoon have been developing over western Elbert County. Marginal risk of severe thunderstorms will be along and south of the Palmer Divide through this evening. Nocturnal thunderstorms may persist along the eastern border late tonight into Sunday morning. Upper level jet continues over the northeast plains until around 09z then lifts north and east. In spite of the weak flow aloft on Sunday, it will remain unsettled with the trough to the west. The mid level trough axis will be along the CO/UT border Sunday morning, and moves very little through 00z Monday. Generally weak mid level QG ascent. Forecast soundings show increasing precipitable water values 0.70-0.90 inches, coupled with afternoon heating will be enough for scattered thunderstorms over the mountains, with isolated to scattered thunderstorms over the northeast plains of Colorado. Better flow in the upper level may help keep the best chance of storms along the CO/KS border. As precipitable water values increase, the greatest threat from the storms will be moderate to heavy rain showers. If there is a marginal risk for severe storms it will be along the CO/KS line Sunday afternoon. .LONG TERM...(Sunday night through Saturday) Issued at 1252 PM MDT Sat Sep 1 2018 As we move into Sunday night and the beginning of next week, an upper level trough will be the dominant feature with south to west flow advecting moisture into the region. There will be scattered late day convection through Tuesday evening with warm temperatures and a weak upper level speed max present over northeastern Colorado. Tuesday night a cold front is progged to move through the area ushering in cooler temperatures from the northwest. Wednesday will be cooler with 700 mb temperatures near 6 degrees C, roughly 5 degrees C of cooling. Thursday through the end of the week an upper level ridge is expected to develop bringing drier conditions to the plains and northwesterly flow. Temperatures should return to near seasonal normals. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 831 PM MDT Sat Sep 1 2018 Surface winds expected to return southeast and south over kden through midnight. Overall, expect a lesser chance for storms Sunday afternoon with weak subsidence over the area. could be some stratus later tonight and Sunday morning but looks like will stay east of the terminals. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Entrekin SHORT TERM...Cooper LONG TERM...Sullivan AVIATION...Entrekin
Area Forecast Discussion...Updated
National Weather Service Billings MT
835 PM MDT Sat Sep 1 2018 .UPDATE... Forecast is on track. Winds remain a little gusty out of the northeast as a weak, dry front moves across the area. Winds still expected to decrease overnight. Satellite shows some wildfire smoke across north-central Montana, and the HRRR smoke shows maybe some of this smoke might work down with the front. However if anything does work down, it is very minimal. Reimer && .SHORT TERM...valid for Sun and Mon... Little in the way of changes for the short term forecast. The forecast continues to look mainly dry through the short term, with mainly dry zonal flow in place through Monday morning. This should shunt monsoon moisture to the south, while the better energy stay north of the region. Low level winds turns to the southeast Sunday and Sunday night, as sfc trof develops over the area. This should bolster moisture availability in the southeast. Meanwhile, southwest flow returns aloft, possibly bringing monsoonal moisture back into he region. This could point to some isolated showers and thunder Monday afternoon/evening. Activity in west should be slower to develop as airmass remain dry. Another disturbance will shift into the northwest Monday night, bringing a chance for showers in the west. High temperatures through Labor Day will be at, or slightly above, seasonal averages. AAG .LONG TERM...valid for Tue...Wed...Thu...Fri...Sat... Confidence is high in a rather cool Tuesday across the region. There is a weak short wave that could produce a few showers, but the lower levels look pretty dry so we will maintain just slight chance PoP`s. Temps should bounce back quickly as 500mb heights build over the area Wednesday and Thursday ahead of a trof off the British Columbia coast. The flow aloft does turn to the southwest by Thursday evening opening the door for some mid level moisture. So some showers/thunder may affect our western mountains late in the work week. Both the ECMWF and GFS progs suggest a noisy zonal flow developing next weekend. So seasonal temps and low PoP`s continue to look reasonable. BT && .AVIATION... VFR conditions will prevail tonight through Sunday. Surface wind gusts E of KBIL will diminish by late this evening. Arthur && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 050/081 053/083 052/066 047/079 053/086 056/086 057/079 00/U 00/U 02/W 00/U 00/U 20/B 21/B LVM 043/081 045/083 045/068 042/079 050/085 053/082 051/076 00/U 00/U 11/B 00/U 01/U 21/B 21/B HDN 050/083 051/085 052/068 048/081 052/087 056/088 056/081 00/U 00/U 02/W 00/U 00/U 20/U 21/B MLS 051/082 056/088 054/068 049/077 055/087 060/087 058/081 00/U 11/U 12/W 00/U 00/U 10/U 21/B 4BQ 050/081 055/087 053/070 048/078 054/087 055/087 057/083 10/U 11/U 12/W 00/U 00/U 10/U 11/B BHK 048/077 054/086 051/067 045/072 052/083 054/083 055/080 10/U 12/T 22/W 00/U 00/U 00/U 11/B SHR 047/082 049/085 050/069 046/080 050/085 052/086 051/080 00/U 00/U 01/U 00/U 00/U 10/U 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings
Area Forecast Discussion
National Weather Service State College PA
1141 PM EDT Sat Sep 1 2018 .SYNOPSIS... High pressure will build into the region over the next several days, settling over the Mid-Atlantic states by early in the work-week. This high will provide another late-season taste of summer with warm, humid and mainly dry conditions through the middle of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Surface high pressure is nosing in all the way from the Canadian maritimes and providing a moist southeasterly flow off the Atlantic Ocean, keeping much of central and eastern PA blanketed beneath low clouds. Scattered rain showers that developed earlier across western PA are slowly progressing eastward. The HRRR pushes this activity eastward across central PA overnight, although it should tend to diminish. Low clouds will persist. The clouds and high dewpoints will keep overnight temperatures mild for early September, with forecast lows in the 60s to low 70s being some 10-15 deg above normal. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday will start out cloudy and a bit damp, but with the low level flow becoming more southwesterly through the day, we should see skies gradually become partly to mostly sunny by afternoon with a return to warmer conditions. Dewpoints well up in the 60s and lower 70s will make it feel like mid-summer. A shower or thunderstorm cannot be ruled out, especially during the afternoon. && .LONG TERM /MONDAY THROUGH SATURDAY/... Strong upper ridge will rebuild over the region early this period with very warm to hot and humid conditions prevailing for much of the coming week. Anomalous PWATS spread northward on Sunday and remain over the region through this period. Well above normal temperatures, high humidity and scattered diurnally-driven convection are expected each day under this regime. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Just updated the TAFS. Only a few light showers left on the radar over central PA. Did back off on the lower conditions some. Earlier discussion below. For the 00Z TAF package. More in the way of showers and storms formed just before 6 PM, are starting to weaken now. PW values not quite as high as yesterday, thus storms less likely to hold together too much longer. Later this evening the focus will be on lowering ceilings as low levels cool/moisten. Model soundings support indicate some locations dipping to IFR by midnight. MVFR/IFR at most terminals to start the day should burn off to VFR by mid day into the afternoon. Scattered mainly afternoon showers/storms could bring local restrictions. .Outlook... Mon-Thu...Patchy AM fog possible. Isolated PM shower/thunderstorm impacts possible. && .CLIMATE... Williamsport saw the wettest summer on record with 23.73 inches of rain. The previous wettest summer was in 1972 when Hurricane Agnes helped push totals to 22.30 inches. State College saw their wettest summer with 22.14 inches of rain Their previous wettest summer was back in 2003 when 19.83 inches of rain fell. Harrisburg saw the second wettest summer on record with 21.37 inches of rain. The wettest summer was in 1972 when Hurricane Agnes contributed to the 23.33 inch record. Altoona saw the fifth wettest summer on record with 16.39 inches of rain. 1972 was also their wettest year with 17.77 inches of rain. The most remarkable aspect of this summer`s extreme rain was that we had no contributions from Tropical Cyclones. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Evanego NEAR TERM...Evanego SHORT TERM...Evanego LONG TERM...DeVoir/Fitzgerald AVIATION...Martin CLIMATE...La Corte
Area Forecast Discussion
National Weather Service Quad Cities IA IL
644 PM CDT Sat Sep 1 2018 ...AVIATION UPDATE... .SYNOPSIS... Issued at 241 PM CDT Sat Sep 1 2018 MCS fueled by strong LLJ gradually weakened during the morning hours, giving way to a mix of clouds and sunshine across much of the region early this afternoon. Analyzed surfaces maps and observations at 18Z showed a large area of high pressure over the southeast U.S, which was keeping the Midwest under a warm, moist flow. At the surface, a wavering frontal boundary stretched from western IA to north central IL. Temperatures as of 2PM ranged from 77 in Dubuque, to 86 in Fort Madison and Mount Pleasant. && .SHORT TERM...(This Evening through Sunday) ISSUED AT 241 PM CDT Sat Sep 1 2018 Challenging short term with the main concerns set on precipitation and severe storm chances. This evening, expecting additional showers and storms to fire up across the region along the frontal boundary and remnant boundaries from the morning MCS. The front is expected to set itself up between Highway 34 and the I-80 corridor based on current mesoanalysis of moisture transport, and current NAMnest agrees by firing activity along a line from Williamsburg, IA to Freeport, IL. Believe the HRRR and NAM are too far north with development and QPF along and north Highway 20. After this moves through, expect a LLJ to fire additional precipitation back to the west over central IA around midnight, which will move east through the night. With PWATs approaching 2.00" on forecast soundings and precip moving over the same areas that saw heavy rainfall last night, expecting the primary threats from showers and storms to be additional heavy rainfall and isolated flash flooding. Currently have total QPFs of 1-2 inches along and north of I-80 to the Highway 20 corridor, but higher amounts are possible with heavier showers/storms. In addition, a window for severe storms exists this evening, especially since skies have opened up early this afternoon. With the clouds clearing, ample moisture and steepening lapse rates will allow CAPE values to climb to or above 3000 J/kg. Combined with forecast 0-6 km wind shear of 30-40 kts, storms that develop this evening will have the potential to produce large hail and strong winds. SPC maintains a marginal risk of severe storms through 12z Sunday. Expect a similar scenario Sunday as the frontal boundary moves little and interacts with an upper level disturbance moving across the region. SPC has a marginal risk of severe storms along and north of the I-80 corridor, with threats of isolated large hail and strong winds. .LONG TERM...(Sunday Night through Saturday) ISSUED AT 241 PM CDT Sat Sep 1 2018 An active and wet pattern is expected to continue through the period as abundant tropical moisture surges north into the area. While overall pattern with H5 ridge axis may change in later forecasts, the current set up is for heat, humidity and thunderstorms with heavy rain. This set up will likely exasperate any flooding potential through the period. Synoptic setup is for the subtropical high to be in place across the eastern US. To our west, a broad southwest flow will continue the feed of moisture into the area as a weak frontal boundary will remain across the area. Weak waves with move through the flow from the southwest as well as tropical waves from the the gulf of Mexico. Each of these waves will bring chances for storms across the area. With high PWATs, 90 percentile or better according to the NAEFS, heavy rain looks likely. In all likelihood, the daily occurrences of storms will be driven by mesoscale features that will change on a daily basis. Overall confidence on placement of storms is low, overall confidence on occurrence of storms is high. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) ISSUED AT 641 PM CDT Sat Sep 1 2018 VFR to mostly VFR conditions with episodes of MVFR conditions the next 24 hours, mainly due to showers and storms. The highest risk is at DBQ and CID terminals. Winds will be southerly at 5 to 10 mph. Skies will tend to mostly cloudy north and mostly partly cloudy in the south. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Flash Flood Watch through Sunday morning for Benton-Buchanan- Cedar-Clinton-Delaware-Dubuque-Iowa-Jackson-Johnson-Jones- Keokuk-Linn-Louisa-Muscatine-Scott-Washington. IL...Flash Flood Watch through Sunday morning for Carroll-Jo Daviess- Rock Island-Stephenson-Whiteside. MO...NONE. && $$ SYNOPSIS...Speck SHORT TERM...Speck LONG TERM...Gibbs AVIATION...16
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1033 PM EDT Sat Sep 1 2018 .SYNOPSIS... A strong upper-level ridge will dominate the Southeast through the middle of next week, resulting in above normal temperatures and reduced precipitation chances outside of the mountains. && .NEAR TERM /THROUGH SUNDAY/... As of 1030 PM: Late evening outflows are driving convection farther west into the foothills. Anticipate that the coverage and intensity will diminish as profiles gradually stabilize through midnight. Still expect that upslope flow into the eastern escarpment of the mountains will produce lingering isolated to scattered showers, and the HRRR runs continue to feature spotty piedmont showers redeveloping through the early morning hours as well, but the more robust thunderstorms should wane very soon. Another round of mountain valley low stratus and fog is likely given the abundant low level moisture there. Minimum temperatures should run some 7 to 9 degrees above climo given the warm and moist boundary layer. The upper ridge will remain in place Sunday with a moist low level easterly flow. Expect a downturn in convective coverage with the ridge helping lower instability. However, there should be enough moisture and instability for scattered coverage over the mountains and isolated coverage elsewhere. Thickness values actually drop a little Sunday despite the ridge. This with the potential for morning clouds should keep highs a little lower than Saturday`s readings. Still, expect highs around 5 degrees above normal. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 245 PM Sat: The East Coast ridge will approach peak intensity during the short-range period, possibly topping out at 597dm heading into Tuesday. The impact of the ridge is significantly more evident in the PoPs and total water content than it was yesterday, with the much lower PoPs in the overnight forecast carried over into today`s guidance and PWs nearer to the 75th percentile (~1.5 inches) than the 90th percentile. The 700-850 mb inversion is progged to be a bit stronger on Tuesday as the ridge strengthens over the Mid-Atlantic, translating to a stronger cap. Furthermore, the upslope-inducing easterly and southeasterly flow into the region appears to be less influential on convective initiation and coverage in recent guidance during the period. Therefore, the net effect will be negligible diurnal precip chances over the Piedmont and only slight chances over the mountains. We continue to advertise a localized heavy rain threat with any storm that develops due to very week steering flow and healthy PWs, but PWs aren`t high enough and these pulse cells should last long enough to be overly concerned. Ample subsidence-induced dry air is present in the mid-levels so isolated strong downdrafts remain possible, but this threat is also decreasing. If anything, the sudden lack of rainfall over the past couple of weeks across much of the area may be the greater concern for many. Temperatures remain 2-4 degrees above-normal which isn`t too bad considering the strength of the ridge, but humidity values will remain quite uncomfortable. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 245 PM Sun: As mentioned above, the Eastern ConUS ridge will peak in intensity Tuesday into Wednesday and then slowly breakdown heading into next weekend in response to height falls over the Northeast and Great Lakes regions. As shortwave energy depicted by an elongated vorticity axis drops south into the Mid-Atlantic, an associated weak cold front will also drift south. As the ridge breaks down, guidance becomes more bullish about diurnally driven convective chances, increasing PoPs to high-end chance (40-55%) across the mountains and introducing chance PoPs across the Piedmont and Foothills beginning Wednesday but especially Thursday through Saturday as the front approaches the area (but remains to our north). These increased chances are in response to increasing laspe rates as the column aloft cools somewhat and the persistent presence of weak easterly to southeasterly flow, which will advect moisture, induce upslope forcing, and perhaps alllow the seabreeze to work into the central Carolinas. Total moisture content will increase a bit as well late week so with continued weak steering flow the localized heavy rain threat will increase into the weekend as well. Max temperatures change little despite the pattern evolution, remaining 2-4 degrees above normal. Guidance wants to reduce dewpoints into the middle and upper 60s with slight reductions in min temperature late week despite increasing moisture. We shall see if this trend continues in future cycles. The guidance is grumbling about increased activity over the northern Gulf in association with tropical waves propagating through the easterly flow to the south of the ridge as we head into late week, but with the ridge decaying overhead the deepest moisture at this time is pushed well west of our area. During the peak of the tropical season, upper-level ridges are our best friends. Nevertheless, that moisture will take a circuitous route around the ridge into the Mid-South and Ohio Valley and pool along the front as it sags south. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: Outflow driven TSRA will impact mainly the NC foothills through midnight and generally avoid the TAF sites. Anticipate the development of low stratus and fog, most likely LIFR or worse, in the mountain river valleys overnight. However, given the rainfall and ENE winds along the I-40 area, MVFR to IFR stratus should form near KHKY, and MVFR clouds could flirt with KCLT toward daybreak. Will keep KCLT and the Upstate TAF sites VFR for now overnight. Redeveloping cumulus is expected on Sunday and convective coverage may be a bit less with the building ridge aloft. Expect ENE flow through the period, except possibly turning SE at KAND on Sunday. Light winds at KAVL will come up initially from the NW Sunday morning and then turn SE during the afternoon. KAVL will see the best scattered thunderstorm chances as well Sunday afternoon. Outlook: Scattered diurnal showers and thunderstorms are expected each afternoon Sunday through Tuesday. Areas of fog and low stratus can also be expected each morning, primarily in the mtn valleys. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 100% High 90% High 100% KGSP High 100% High 100% Med 78% High 100% KAVL High 100% Low 48% High 89% High 100% KHKY High 100% Med 62% High 82% High 100% KGMU High 100% High 100% Med 79% High 100% KAND High 100% High 100% High 82% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JPT NEAR TERM...HG SHORT TERM...JMP LONG TERM...JMP AVIATION...HG
Area Forecast Discussion
National Weather Service Wichita KS
928 PM CDT Sat Sep 1 2018 .UPDATE... Issued at 923 PM CDT Sat Sep 1 2018 Challenging short term forecast. In the near term, RAP has had the nod, with precipitation continue to wane in central KS. It also picked up on the next round of precipitation moving out of the southwest. This has weaker upper support, but given richer moisture and potential for weak warm air advection with veering flow aloft later, it seems plausible that rain could move into the western part of the forecast area in the predawn hours and linger well into the morning. Will assess and thunderstorm watch shortly. Another question is whether anything will develop in southeast KS. That is much less certain. Clearly low level moisture will continue to stream into that region, but weakening and backing flow later in the morning makes elevated precipitation less likely. May see relative lull late morning before next round starts up in central KS in the vicinity of surface baroclinic zone. Generally transitioning precipitation forecast from mostly RAP based to mostly NAM based Sunday morning. Of note, new NAM is quite agressive with QPF near/just north of forecast area in central KS tomorrow night, but midnight shift will need to assess its validity with additional data. -Howerton && .SHORT TERM...(This Evening through Monday Night) Issued at 355 PM CDT Sat Sep 1 2018 Tonight: The primary focus remains on thunderstorms that approach severity over much of Western & part of Central KS where closest to a weak approaching mid-level shortwave. An area of thunderstorms has been ongoing over primarily Northwest KS almost all day. Situation may be complicated by the extensive mid-upper deck cloudiness that has been inducing inhibition. Regardless greatest thunderstorm chances would still target Western & North-Central KS as well as Southern Nebraska where greatest 6-8KM bulk shear (30-40kt) will reside. As such have kept highest probabilities (~40%) assigned generally to the 5 northwestern-most counties. MLCAPES 2,000-2,500 J/KG (Per SPC mesoanalysis) coupled with the increasing bulk shear induced by the approaching shortwave would no doubt translate into these areas being at greatest risk for severe convection. Rest Of Labor Day Weekend: Thunderstorms capable of heavy rains will gradually increase, especially across Central KS as weak front settles S/SE toward these areas. Greatest deep-layer shear remains entrenched from Western KS to the IA/MN state line & as such from a standpoint of severity the thunderstorms should behave. .LONG TERM...(Tuesday through Saturday) Issued at 355 PM CDT Sat Sep 1 2018 Forecast remains essentially unchanged with heavy rain-producing thunderstorms have extended stays across the Great Plains. Lift is lacking, but high octane moisture remains entrenched across nearly all of the CWA. (Especially Eastern KS.) As such, flooding will certainly become a concern by mid-week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 646 PM CDT Sat Sep 1 2018 Convective trends will remain the main issue. VFR conditions expected outside of storms. Storms will continue to flirt with KRSL for the next few hours, possibly getting into KGBD. At this point, KSLN should escape this evening barring a strong cold pool developing. Second round is possible 09-15 UTC in mid level warm air advection pattern from KRSL-KSLN-KGBD-KSLN. Isolated storms should develop in the afternoon, but will only mention at KRSL, where probability is highest. -Howerton && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 73 88 72 84 / 20 40 40 50 Hutchinson 73 88 70 84 / 20 40 50 50 Newton 72 87 70 83 / 20 40 40 60 ElDorado 72 87 71 83 / 10 40 30 50 Winfield-KWLD 73 88 72 84 / 10 30 30 50 Russell 68 87 68 84 / 80 60 70 50 Great Bend 70 88 68 84 / 50 40 70 50 Salina 73 88 70 84 / 20 50 60 60 McPherson 73 87 70 84 / 20 50 60 60 Coffeyville 72 87 72 84 / 10 30 20 50 Chanute 72 87 71 84 / 10 30 30 50 Iola 72 86 71 83 / 10 30 30 50 Parsons-KPPF 72 87 71 84 / 10 30 20 50 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...PJH SHORT TERM...EPS LONG TERM...EPS AVIATION...PJH
Area Forecast Discussion
National Weather Service Wilmington OH
947 PM EDT Sat Sep 1 2018 .SYNOPSIS... Hot and humid conditions will occur into mid week. A cold front will sag south into the region late in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Mostly clear skies across the area this evening will continue into the early morning hours. However, we may begin to see a bit of an increase in clouds across the south late tonight as some low to mid level moisture tries to work up toward the Ohio Valley. This could also lead to a slight chance of showers toward daybreak. With dewpoints running in the upper 60s to lower 70s, do not expect temps to drop off much more overnight with morning lows mostly in the upper 60s to lower 70s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... 12Z models continue to hint that elevated showers may develop around or shortly after daybreak, similar to today. Any activity should decrease in coverage into midday. It looks like any convection in the afternoon will be quite isolated with a somewhat better chance in northern counties. Dew points are forecast to remain in the lower 70s, so with highs approaching 90, heat indices will be in the mid to upper 90s. Clearing in the evening with lows in the upper 60s to lower 70s once again Sunday night. && .LONG TERM /MONDAY THROUGH SATURDAY/... Ridge firmly in place across the area through first half of forecast period. This should lead to minimum convective activity with only isolated events expected mainly afternoon and early evening. Heat indices should reach mid and upper 90s most places so will continue to mention in HWO for now. Ridge should begin to start to break down by end of the week. Models indicating moisture from tropical system may impact the region by Friday and Saturday which could lead to some heavy rainfall potential. This will be subject to where tropical system ends up in flow but will up pops a bit for this period for now. If clouds and rain materialize then temps will be affected which should already be lowering as axis of warmest air gets pushed off to the east and south. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Shower and thunderstorm activity has been gradually dissipating across central Ohio over the last couple of hours. It looks like a few showers may linger at the the central Ohio TAF sites for another hour or so. Otherwise, skies will continue to clear from the southwest through the rest of this evening with mainly clear skies expected overnight. A weak low level jet is forecast to develop late tonight and both the GFS and RUC are suggesting that perhaps a few showers may even develop toward daybreak along the Ohio River. Will therefore go ahead and allow for a bit of an increase in clouds late tonight into Sunday morning across the south to account for this. Scattered cu will then be possible through the day on Sunday along with the possibility of an isolated shower or thunderstorm. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS... NEAR TERM...JGL SHORT TERM... LONG TERM...Padgett AVIATION...JGL
Area Forecast Discussion
National Weather Service Jacksonville FL
750 PM EDT Sat Sep 1 2018 .UPDATE...Radar is presently showing the scattered showers/t-storms that were occurring well inland during the afternoon have come to an end. Radar is also showing an increase in showers over coastal waters... with a few moving over coastal counties. The HRRR and higher-res NAM are not showing this at all. Update will include low POPs for widely scattered showers to move just inland before falling apart the next few hours. Anticipate some decrease in this activity later in the evening, with more possibly redeveloping toward dawn. Low temperature forecast Tonight looks good. && .AVIATION...VFR conditions next 24 hours. Potential for a few areas of generally light fog. Included potential for light fog at KVQQ and KGNV. Included VCTS for scattered TSRA that, like Today, may start and end earlier than typical. Have VCTS generally in the 17z-22z period. && .MARINE...With the Bermuda-Azores ridge entrenched to our north will see an extended period of onshore/easterly flow through the middle of next week. Winds will average 10 to 15 knots with seas of 3 to 5 ft. As the tropical wave passing to our south tightens up the gradient on Monday an increase of winds and sea to 15 to 20 knots and 4 to 6 feet are possible. The onshore flow will bring scattered showers and embedded storms through the period with the best chances over the offshore waters. Rip Currents: Elevated risk will continue in onshore flow pattern. && .PRELIMINARY POINT TEMPS/POPS... AMG 72 91 72 91 / 10 40 10 50 SSI 76 87 76 86 / 20 40 30 50 JAX 75 89 74 88 / 10 40 20 50 SGJ 75 87 74 85 / 20 30 30 50 GNV 73 90 73 89 / 10 40 10 60 OCF 73 91 73 89 / 10 40 10 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Wolf/Zibura/Cordero
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
614 PM CDT Sat Sep 1 2018 .UPDATE... Issued at 613 PM CDT Sat Sep 1 2018 A new forecast is in place using a 50-50 blend of the HRRR and model consensus. This carries the developing thunderstorms across the Panhandle east through wrn and ncntl Nebraska this evening. && .SHORT TERM...(This evening through Sunday) Issued at 350 PM CDT Sat Sep 1 2018 Unsettled weather is expected for much of north central Nebraska through Sunday. A front will remain draped across the central US resulting in a period of wet weather across the region. While thunderstorms are possible, severe weather is not anticipated. The best locations to see heavier precipitation and isolated thunderstorms will be along and south of a line from Imperial to O`Neill. However, most of the forecast area will see some rain between this afternoon and Sunday afternoon. While model consensus is in fairly good agreement on the upcoming system, there is still some concerns for the next day. If this front can push a little further south and east, the precipitation potential across the forecast area will diminish. Due to the model agreement this is unlikely to happen, however, will need to keep an eye on development over the next several hours in case adjustments are needed. As far as temperatures are concerned, tonight expect a gradual range from the mid 50s across the eastern Panhandle to the mid 60s east of a line from Burwell to Spencer. Clouds and rain will keep temperatures slightly cooler on Sunday. Expect highs to only rise into the upper 70s to low 80s by the afternoon. .LONG TERM...(Sunday night through Saturday) Issued at 350 PM CDT Sat Sep 1 2018 Unsettled conditions will continue to prevail through Wednesday with temperatures generally cool to near seasonable through Thursday. The coolest readings are expected on Wednesday with highs about 8-12 degrees below seasonable values. Thereafter dry conditions and seasonable temperatures are anticipated Friday and Saturday. On the whole the large scale pattern will be characterized through Tuesday night by a broad upper-level trough over the western CONUS and a mid-level high centered near the Middle Atlantic/Middle Atlantic coast. While broad troughing generally weakens Tuesday- Tuesday night over the western CONUS, late Tuesday and Tuesday night appear to hold the greatest chances in terms of coverage and rainfall amounts presently. Prior to Tuesday, several embedded disturbances in the flow promote modest chances, however, better chances appear to be east of the local forecast area. A weak cold front will reach the area Tuesday from the north/northwest and will advance through overnight. Of which, this frontal zonal will help serve as a focus for precipitation, especially for over the southeast-half of the local forecast area late Tuesday-Tuesday night. While locally heavy rainfall appears as a threat in this time frame, the combination of poor lapse rates at mid-levels (700-500 hPa), so-so deep layer shear, and weakly to moderately unstable conditions lowers the overall concern for severe thunderstorms. Moisture and storm motion appears favorable in this time frame with precipitable water values exceeding 1.25/150% of normal and slow motion forecast (less than 10 kts possible Tuesday night) with a favorable orientation relative to the boundary. Thereafter, weak ridging then builds on Wednesday. The forecast then Wednesday-Thursday night appears to be trending drier with lower chances/isolated to scattered in coverage. Meanwhile, near seasonable highs Monday and Tuesday will be followed by cool highs Wednesday. Wednesday highs largely around 70 area-wide. Temperatures look to rebound by Friday with highs forecast in the mid 70s to lower 80s, near seasonable values. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 613 PM CDT Sat Sep 1 2018 The developing area of thunderstorms across the Panhandle should move east through wrn and ncntl Nebraska tonight. Forecast confidence is highest along Interstate 80 and lowest across highway 20 and highway 2. MVFR/IFR cigs are expected to develop along and south of highway 20 including Interstate 80, 09z-17z Sunday morning. Otherwise, VFR is expected overnight and Sunday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...CDC SHORT TERM...Kulik LONG TERM...ET AVIATION...CDC
Area Forecast Discussion
National Weather Service San Francisco Bay Area
901 PM PDT Sat Sep 1 2018 .SYNOPSIS...A modest warming trend is forecast through Labor Day as high pressure strengthens offshore. Interior locations will warm into the 80s and 90s while 60s and 70s will will continue near the coast. Dry weather conditions along with seasonable temperatures are forecast to persist through next week. && .DISCUSSION...As of 9:00 PM PDT Saturday...The warming trend that got underway on Friday stalled today, with some locations even cooling a few degrees. This was mostly due to an unexpected increase in the depth of the marine layer late last night and this morning. Latest Fort Ord Profiler data shows the marine layer depth has settled back down to about 1500 feet. The models continue to forecast warmer temperatures across inland areas for the rest of the long Labor Day Weekend as an upper ridge centered off the southern California coast strengthens a bit. The ECMWF forecasts less robust warming compared to the GFS and believe the Euro model has a better handle on temperatures over the next few days given that onshore flow is forecast to persist at the low levels. Latest HRRR smoke model indicates decreasing near surface smoke through this evening, but then increasing smoke concentrations developing late tonight through Sunday, especially in the North Bay, as light northerly flow develops aloft. Longer range models agree that the upper ridge off the southern California coast will build eastward across SoCal by the middle of next week. But at the same time, a trough is forecast to develop across the Pacific Northwest. These two developments will mostly offset each other across our area, where H5 heights and 850 mb temps are not expected to change much. In addition, onshore flow is forecast to persist through the week. So we can expect continued near normal temperatures through next week with no significant changes in our weather. && .AVIATION...as of 4:44 PM PDT Saturday...For 00z TAFs. A relatively modest, and dry, northerly gradient is evident on the visible satellite loop, clearing stratus north-to-south along the Sonoma/Marin County coastline. In addition to the moderate northerly gradient in place, the marine layer is expected to compress overnight as high pressure aloft builds over the area. Stratus is still expected to develop and penetrate coastal terminals overnight, with MVFR/IFR/LIFR conditions anticipated overnight. Doubts of cigs reaching terminals such as KSTS, KSJC, and KLVK exists and are reflected in the TAFs, but will monitor conditions through the night. If cigs do develop at these locations, it will be around sunrise Sunday morning and will only last a couple of hours. Light winds overnight, expected to remain onshore through Sunday afternoon, 10-15 kt on average. Moderate forecast confidence. Vicinity of KSFO...Currently VFR. Breezy west winds will decrease after 04Z this evening. Will have to monitor the stratus deck along the San Mateo coast over the next few hours to see if it can penetrate through the San Bruno gap. Otherwise, expect MVFR cigs to return by 06Z or so. Breezy WNW winds by early Sunday afternoon. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...MVFR cigs have hovered over KMRY and the stratus deck is making its way over KSNS as of writing this. MVFR cigs will gradually drop to IFR before midnight and likely LIFR at KMRY after midnight. With a more compressed marine layer expected, could have a few hours of dense fog around sunrise Sunday. && .MARINE...As of 8:48 PM PDT Saturday...High pressure over the Eastern Pacific will continue interacting with a thermal trough, keeping northwest winds moderate to strong over the coastal waters tonight and into Sunday morning. The strongest winds will be over the northern outer waters and waters south of Point Sur, along the Big Sur coast. Winds will gradually decrease through Sunday evening and into Monday as the trough weakens. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...GLW...Pt Arena to Pigeon Pt 10-60 nm GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM SCA...Pt Arena to Pt Reyes 0-10 nm && $$ PUBLIC FORECAST: Dykema AVIATION: BAM MARINE: BAM Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Omaha/Valley NE
608 PM CDT Sat Sep 1 2018 .SHORT TERM...(Tonight through Tuesday) Issued at 351 PM CDT Sat Sep 1 2018 The main forecast problems during the forecast period is severe weather and heavy rain. A surface cold front extending from north central Iowa to south central Nebraska is forecast to move little during the forecast period. Along and south of surface front surface dewpoints are in the lower 70s. ML CAPE values are at 17Z between 500 and 2000 J/Kg. This will increase to around 3000 J/Kg with continued surface heating south of the front over southeast Nebraska. Forecast 0-6 KM bulk shear over southeast Nebraska is expected to be between 35-40 kts, which is sufficient for a severe thunderstorm development. Water vapor imagery indicate upper short wave lifting out northeast out of near the KS/CO border. This wave is expected to enhance convective development across northern Kansas and south central Nebraska. HRRR models indicate a complex of storms reaching the southwestern portion part of the OAX CWA by 00Z and then moving northeast to near LNK and BIE between 01-02Z and to OMA by 03Z. Main hazards will be larger hail and damaging winds with After that wave goes through, convection lingers on through the night. This lingering convection brings up the possibility of flash flooding. PW values from model soundings in eastern Nebraska and western Iowa are forecast to be 1.5 to 1.8 inches,which is high for this time of year. Planning on doing a flash flood watch to cover southwest Iowa and several counties in southeast Nebraska. Depending on what happens tonight, a flash flood watch is a distinct possibility for Sunday or Monday as more waves of thunderstorms move across the area due to the surface front stalling out across southeast Nebraska and western Iowa. Models bring in another wave of storms mainly Sunday night and again on Monday. Front lifts northward Monday night into Tuesday with thunderstorms again possible during the day. .LONG TERM...(Tuesday night through Saturday) Issued at 351 PM CDT Sat Sep 1 2018 Tuesday night, another round of storms is forecast to move into the area as the front moves southward This activity and continue into Wednesday. After Wednesday, front moves into Kansas and Missouri. But, thunderstorm activity may linger on and off through Sunday over southeast parts of Nebraska. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 553 PM CDT Sat Sep 1 2018 Thunderstorms activity is expected to develop at all TAF sites this evening. LNK and OMA will see the storm potential increase from 01-03z at LNK and OFK and 02-04z at OMA. Some of these storms tonight have the potently to be strong to severe, particularly over southeast Nebraska impacting LNK and OMA. Scattered storms are expected to continue overnight with off and on rain chances through Sunday. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Flash Flood Watch through Sunday morning for NEZ045-050>053- 065>068-078-088-089. IA...Flash Flood Watch through Sunday morning for IAZ055-056-069-079- 080. && $$ SHORT TERM...Smith LONG TERM...Smith AVIATION...HB
Area Forecast Discussion
National Weather Service Pueblo CO
633 PM MDT Sat Sep 1 2018 .UPDATE... Issued at 630 PM MDT Sat Sep 1 2018 Northern El Paso seems to be the hot spot for precipitation this evening, behind boundary that has moved south. Have boosted pops there for a couple hours. On the other hand, the far southeast plains are quieter than expected. Have lowered pops there. && .SHORT TERM...(This evening through Sunday) Issued at 329 PM MDT Sat Sep 1 2018 Currently... Water vapor imagery clearly shows a broad mid level trough located over the southwestern CONUS. Several weak disturbances were associated with this trough, with the most active disturbance down in NM. Over the greater forecast area, a broad surface low was located over the plains, with a boundary extending from the Pikes Peak region up towards the greater Limon area. A few showers and -tsra were noted along this feature. Rest of today and into tonight... With the broad trough over the region and weak forcing at the surface, showers and thunderstorms will be likely across the region through this evening. All guidance indicates this, however some simulations are more aggressive than others. HRRR wants to highlight the SW mtns and Palmer Divide, while the hi res NAM is a bit hotter over the SW Mtns and both divides (Palmer and Raton). SPC real time guidance products showing best CAPE over the far eastern plains, but deep shear is rather weak across the entire region. Given this, believe we will see isold showers/storms along the mtns/plains interface later this afternoon with activity pushing east of the interstate after 6 pm. Still can`t rule out a stronger storm over the far eastern plains later this evening. Overall best chance of storms will be this afternoon/early evening over the sw mtns. For tonight, with broad trough aloft over the region, cannot rule out isold activity over the valleys and plains. There will be a better chance of late night activity over the contdvd. Overall, expect to see more clouds than normal (mainly upper and mid lvl clouds) over the region tonight. Tomorrow... Broad trough aloft will not move much, although weak disturbances will continue to migrate through the large scale feature. This will keep a chance of showers and storms over the region tomorrow. A jet streak is noted over the se Plains tomorrow afternoon, and sufficient low level upslope/moisture will be in place; likewise we will see a continued chance for a strong storm or two. Once again, all guidance shows storms over the region tomorrow but models vary on location and intensity of the precip. Burn scar flash flooding will be possible tomorrow. .LONG TERM...(Sunday night through Saturday) Issued at 329 PM MDT Sat Sep 1 2018 The upper level trof remains in place over the southwest U.S. through at least Tuesday with several upper level disturbances moving across southeast Colorado during the period. Subtropical moisture also continues to move northward from northern Mexico and the Gulf of Mexico. Scattered thunderstorms are expected to develop over the mountains each afternoon and linger through the evening on the plains through the first part of next week. Latest models a little slower building ridge into the southwestern U.S. and bringing in drier air. Looks like the moisture plume shifts eastward and drier weather will move into our area by Friday and continue into the weekend. At the surface, a cold front moves south through the plains Tuesday night and brings cooler, more stable air to the plains for Wednesday. Still could see a few late day showers and thunderstorms develop over the mountains. Wednesday will be the coolest day of the extended period with highs mainly in the 70s on the plains. Temperatures warm up Thursday with warmer and drier conditions expected Friday and Saturday with highs generally in the 80s at the lower elevations. Stark && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 329 PM MDT Sat Sep 1 2018 VFR conditions are expected during the next 24 hours at all 3 taf sites; KPUB, KALS and KCOS. The only exception will be brief periods of MVFR with thunderstorms this afternoon/evening and tomorrow afternoon/evening. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...LW SHORT TERM...HODANISH LONG TERM...STARK AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Tucson AZ
235 PM MST Sat Sep 1 2018 .SYNOPSIS...Expect isolated to scattered showers and thunderstorms especially from Tucson eastward through Labor Day. Daytime temperatures will generally be a few degrees below normal. A gradual drying trend will then occur later next week, with the bulk of thunderstorms mainly east of Tucson. && .DISCUSSION...The upper pattern this afternoon is defined by an upper trough of low pressure over Nevada/Utah and a ridge of high pressure SW of California in the Eastern Pacific. The latest satellite imagery indicated a distinct moisture boundary extending NW-to-SE across Arizona along the SW periphery of the mean trough. We have seen the more sustained storms firing up along this boundary from Mt. Graham to the bootheel of New Mexico. There has been a few different waves of storms to track through the Pinaleno Mountains this afternoon, with a broad area of rainfall in excess of 1.50 inches, including portions of the 2017 Frye Fire burn scar. We have already seen a 3 foot rise of water flowing thru Ash Creek. The more favorable dynamics with this upper trough are N and NE of our CWA in NE AZ and WRN NM. However, as the upper trough continues to sag south, it will result in an upper diffluent field establishing itself across the eastern portions of the forecast area into Sunday. The majority of the Hi-Res models are in agreement with convection continuing to fire up from Tucson east this afternoon. Given the developing diffluent field aloft, I am leaning more toward the 01/12Z UofA WRFNAM solution which maintains convection overnight, especially along the AZ and New Mexico border. This is also reflected to a lesser extent by the 01/20Z HRRR and 01/12Z HREF ARW models. The 01/12Z KTWC upper air sounding indicated ample moisture still present in the lower-to-middle layers of the atmosphere with a PWAT value of 1.40 inches. Given the moist airmass, we will likely have to pay attention to rainfall amounts along the AZ/NM border resulting in minor small stream flooding issues(FLS) through Sunday afternoon. Otherwise...the mean upper trough remains over SE AZ Monday and slowly nudges to the east by the middle of next week as the upper ridge in the Eastern Pacific shifts NE into California. Although this would keep the WRN portions of the forecast area dry this week, enough instability will exist to the east of Tucson...especially if this trough phases up with an inverted trough west moving along the southern periphery of the upper high moving into the Great Basin next weekend. && .AVIATION...Valid through 03/00Z. Scattered -TSRA/-SHRA from KTUS vicinity and eastward into the evening. Focus of activity will shift to mainly east of KTUS overnight, with more scattered -TSRA/-SHRA expected Sunday. SCT-BKN clouds 5k-12k ft AGL along with SCT-BKN clouds AOA 20k ft AGL areawide. SFC wind generally SLY/SWLY at mainly less than 12 kts, though gusts to 40 kts will be possible near TSRA. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered thunderstorms from Tucson eastward through the evening. The focus of thunderstorm activity will shift mainly to areas east of Tucson overnight and into Sunday. A gradual drying trend will occur next week with coverage becoming more isolated across eastern locations. Expect terrain driven 20-foot winds at less than 15 mph, though higher gusts will be possible in and around thunderstorms. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson