Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/17/17


Area Forecast Discussion
National Weather Service Wakefield VA
1038 PM EDT Fri Jun 16 2017 .SYNOPSIS... A weak boundary lifts north of the area through tonight with warm conditions expected through the weekend. Scattered afternoon and evening showers and thunderstorms are expected again Saturday with less coverage expected Sunday. A cold front slowly approaches the region from the west on Monday, stalling over the region through the middle of the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Areas of moderate to heavy rain continue this evening in a moist airmass despite weak forcing aloft. Adjusted PoPs based off latest radar trends and HiRES guidance. Also have issued a FFW for areas just north of Richmond where there are several reports of water on roads. This has been fairly localized however, with no other areas needing any FFW/FLS. Previous Discussion... Anomalously moist air mass remains over the local area as satellite and RAP guidance indicates precipitable waters around 1.9 to 2.1 inches. Shortwave energy over the Southeast has pushed the weak frontal boundary northward into northeast North Carolina, stretching northwestward over the Piedmont. The front has been the focus for widely scattered to scattered showers and thunderstorms across southeast Virginia/northeast North Carolina and the Piedmont. Earlier cloud cover limited overall instability, but RAP analysis indicates mixed-layer CAPE of 1000-1500 j/kg (up to 2000 j/kg over the far southeast. A wave is progged to lift northeast over the Piedmont later this afternoon into this evening, leading to better organization and coverage late today into this evening. Storms are expected to grow upscale, lifting northeast. Best coverage expected across the Piedmont and the southeast half of the forecast area, remaining more scattered into central Virginia. Heavy rainfall remains the main threat. Temperatures in the upper 70`s to low 80`s have limited downdraft potential (DCAPE) and deep layer shear is less than 20 knots, but gusty winds are possible under the strongest storms. Added dynamics and elevated instability expected to keep showers and thunderstorms ongoing through the evening hours west of the Bay. Have retained likely POPs inland this evening. Convection wanes late tonight, but will maintain a slight chance POP inland due to the warm/moist air mass. Mild, with lows around 70. Another night of low clouds and patchy fog expected. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Warm/moist return flow persists over the region Saturday as high pressure remains centered over the western Atlantic. Low pressure centers over the Great Lakes as the attendant cold front remains well west of the local area. Aloft, a baggy trough stretches from the Ohio Valley into the Deep South as the subtropical ridge locates offshore. While the air mass remains quite warm and unstable, a lack of appreciable forcing and a lack of surface convergence expected to result in only scattered afternoon and evening showers/thunderstorms. Warming between 850-700mb also expected to prevent robust updrafts. Best chances expected near the coast associated with sea-breeze boundaries and remnant outflow boundaries. Highs in the mid to upper 80`s. Cooler near the coast. Mild Saturday night with lows generally in the low 70`s. Given the air mass, have kept slight chance to chance POPs through late Saturday night. Little change aloft Sunday as the baggy trough remains over the Southeast. Stronger return flow expected Sunday ahead of an approaching cold front. Precipitable waters fall off to 1.5 to 1.75 inches. Warming aloft and mid-level lapse rates less than 6 C/km will limit overall instability, with guidance indicating mixed-layer CAPE values less than 1,000 j/kg. Perturbations in the southwest flow will provide some subtle forcing for ascent, so anticipate widely scattered to scattered showers and thunderstorms Sunday afternoon and evening across the Piedmont and near any sea-breeze boundaries. Warm, with highs in the upper 80`s to low 90`s. Dry and mild Sunday night with lows in the low to mid 70`s. && .LONG TERM /MONDAY THROUGH FRIDAY/... Rather typical late-Spring/early-Summer conditions are expected to continue into next week. A trough digging over the Great Lakes will push a cold front toward the area Monday into Monday night, resulting in an increasing chc of aftn/evening showers/tstms Monday aftn/Monday night. Increasing flow aloft and a moderately unstable airmass could trigger some locally strong storms with heavy rain. The front lingers in vicinity of the coastal plain of SE VA and the Carolinas Tuesday/Wednesday resulting in 20-30% PoPs Tuesday and aob 20% by Wednesday. The latest data supports dry conditions by Thursday as the boundary washes out. Another boundary/trough may settle into the area by Friday but uncertainty is high at this time. Highs Monday are generally in the upper 80s to around 90, then dropping back to the mid/upper 80s by Tuesday/Wednesday as the front gradually pushes through the area. By Thursday/Friday highs return to the upper 80s to around 90. Lows will generally by in the upper 60s to low 70s through the period. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Widespread showers and thunderstorms are on a slow decrease this evening and the heaviest rain looks as though it will miss all the TAF sites though there will be vicinity shra and tsra at RIC through 01z. Some light rain is possible at PHF and RIC through 02z, but visibility should remain 5sm or better. Overall ceilings are generally VFR with a few pockets of MVFR. however think the TAF sites will all remain VFR for the remainder of the evening. Winds have become variable across the region due to outflows from storm activity, but should return to generally south to southeast at 5 knots or less. The boundary lifts northward tonight into central Virginia, as flow becomes more southerly over the region. The air mass remains quite warm and moist, so expect another round of low ceilings to develop towards daybreak with areas of fog developing again tonight. Scattered to numerous showers expected again Saturday afternoon and evening. Stronger southwest flow Sunday and Monday and less moisture will limit precip chances. A cold front drops into the area Monday night and Tuesday, with more unsettled conditions through mid week. && .MARINE... A weak boundary will lift across the Mid-Atlantic coast as a warm front this evening. Expect mainly a SE wind of 5-10kt, with the potential for localized stronger wind gusts in any tstms. Seas tonight into Saturday will generally be 2-3ft, with a dominant period of 6-8sec, and embedded swell with a period of 18-20sec. High pressure settles off the Southeast coast tonight through the weekend. This will result in predominate southerly flow late tonight into Saturday, with sea-breeze aided SSE flow of 10-15kt is expected Saturday aftn/early evening. The wind will veer back to SSW Saturday night remaining aob 15kt. The pressure gradient tightens Sunday into Monday ahead of an approaching cold front bringing the potential for pre-frontal SCA conditions. This could boost a SSW wind to 15-25kt for the Bay/ocean, 15-20kt for the Sound/Lower James, and ~15kt elsewhere. Seas build to 3-5ft N of Cape Charles, and potentially 4- 6ft out near 20nm, with 2-3ft waves in the Bay. This cold front approaches from the northwest Monday and gradually drops into the coastal plain of SE VA and the Carolinas Monday night into Tuesday, and then dissipated Tuesday night into Wednesday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...SAM NEAR TERM...MAS/SAM SHORT TERM...SAM LONG TERM...AJZ AVIATION...SAM/JAO MARINE...AJZ/MPR
Area Forecast Discussion
National Weather Service Albany NY
1049 PM EDT Fri Jun 16 2017 .SYNOPSIS... Increasingly warm and humid weather along with the threat for showers and thunderstorms through the weekend as a couple of low pressure systems impact the region. Temperatures will rise above normal by Fathers Day before a cold front approaches Sunday night into Monday. && .NEAR TERM /THROUGH SATURDAY/... As of 1045 pm...little change needed to going forecast. Previous discussion follows. As of 745 pm...area of showers has departed to the east, but plenty of lower to mid-level moisture remains, so conditions remain cloudy across the majority of the forecast area. We are in a lull with respect to forcing, so have cut back on PoPs through the overnight hours. A few showers may be possible for portions of the Catskills, Mid-Hudson Valley, NW CT and the Berkshires late tonight as the activity over Central PA attempts to expand northeastward. This activity may be associated with a very weak midlevel wave and enhanced midlevel theta-e. Have included chance PoPs after around 06Z for this potential, but hi-res models indicate anything should be rather light. With moist low-levels fog could be a concern, but absent any breaks in the clouds do not expect dense fog. Will continue to monitor trends, however. Showers continue to track east across the region with the back edge of the precipitation extending across western New England and the Taconics. Some additional convection has developed well upstream of the region within the warmer air and per satellite analysis, ample breaks in the overcast have allowed for surface temperatures to climb well into the 70s where SBCAPES per SPC mesoscale windows in excess of 2000 J/KG. There remains some differences with respect to tonight`s forecast as the NAM pushes through this frontal zone keeping the region mainly dry, perhaps some pockets of drizzle and patchy fog as low levels remain quite moist. The GFS and the latest HRRR pick up on the notion of this frontal zone becoming quasi- stationary as it becomes parallel to the upper flow therefore stalling the forward progress. This allows for a wave to track northeast for additional precipitation in the form of light rain to develop across the southeastern 1/3rd of the CWA. We will keep the chance PoPs for these areas through the overnight as we watch trends unfold. Otherwise, a rather damp night for most of the region as overnight lows range between 55-65F degrees. Saturday a more noticeable increase in low level moisture as dewpoints climb into the 60s. As for cloud coverage, a few breaks are expected as instability parameters show a noticeable increase across the region. Some scattered showers and thunderstorms are possible across the area during the day as SBCAPES climb between 1000-2000 J/KG yet hard to define any definitive surface boundary. Perhaps differential heating and terrain based convection may be able to develop hence the low chance PoPs that remain in the forecast. Highs Saturday are expected to bounce back into the mid 70s to mid 80s with dew points on the rise it will feel like more 80s to near 90F. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... It will be muggy Saturday night with the region in the warm sector with lows in the 60s. Sunday will be warmer and more humid with dew points expected to rise into the upper 60s to lower 70s with temperatures in the upper 70s to upper 80s. A short wave rotating through the trough about the base of an upper level low over Hudson`s Bay will pass to our northwest during the day. The wind field across the region will increase especially to the north and west of the Capital District. As for potential instability, MLMUCAPES will increase to 1000-1500 J/KG across most of the forecast area with 0-6 km bulk shear 30 to 45 kts across most of the area. The Day 3 Severe Thunderstorm Outlook from the Storm Prediction Center has Slight and Marginal risk across about the northwest 2/3 of the forecast area. Will address threat in our Hazardous Weather Outlook along with locally heavy downpours with high precipitable water values across the area with PWs reaching 1.5 to 2 inches by Sunday evening. Chances for convection continue Sunday night as heights begin to fall and the system`s cold front approaches western New York. The threat for severe thunderstorms should wane with loss of heating and a decrease in instability. Another muggy night is expected with lows only into the 60s to lower 70s. On Monday, a sharp upper level trough will be located over the Great Lakes region, with a surface cold front slowly moving eastward across New York State. This cold front will be running into a strong ridge off the east coast, so it will be taking its time as it crosses the area from west to east, with bands of showers and thunderstorms. With a warm and very moist air mass in place PWAT values may exceed 2 inches in some places, thus any shower or t-storm will be capable of producing very heavy downpours. We will need to watch for localized flooding if any heavy rainfall repeatedly occurs over the same location. In addition, there is still a chance of severe weather as MLMUCAPES may rise over 2000 J/KG in places with 0-6 km bulk shear of 35 to 50+ kts possible. Highs on Monday will be in the mid 70s to mid 80s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... The extended period will feature multiple threats for precipitation with near normal temperatures. After a cold front impacts our region during the day Monday, it should shift into our far eastern CWA heading into Monday night so have highest POPS in place in western New England with lower POPs in our western CWA at the start of the extended period. While the surface cold front will likely be east of the area by Tuesday, a longwave trough will be entering into the Northeast and the cyclonic flow could lead to diurnally driven scattered shower threats on Tuesday (esp for the afternoon). Temperatures should not be as warm as Monday falling back into the upper 70s/low 80s but continued SW flow will keep dew points near 60. Once we lose daylight, any scattered showers should diminish Tuesday night. However, a shortwave embedded in the larger scale cyclonic flow looks to swing into our CWA on Wednesday and bring with it yet another threat for showers and perhaps some thunderstorms (again best chance in the afternoon). Given the increased cloud coverage and precip threat, high temperatures should be a bit cooler than Tuesday with highs in the upper 60s for the elevations and upper 70s/near 80 elsewhere. High pressure should build into the area on Thursday finally giving us a break from the consecutive days of precipitation threats and also usher in lower dew points in the upper 40s/low 50s; however, this looks to only be a brief respite as another warm front appears to arrive in the Thursday night/Friday period bringing a returned threat for wet weather. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Despite the departure of showers, low-level moisture still abounds this evening with MVFR/borderline-IFR cigs. Forecast soundings and MOS suggest IFR potential at all sites as stratus builds slightly lower. Low confidence with respect to timing, but have included it earliest at KPOU due to possibly advancing marine layer, and at KPSF due to their higher elevation. Low dewpoint depressions and light winds will likely result in some light fog as well, with some IFR vsby possible. Cannot rule out patches of dense fog, but this appears conditional upon cloud breaks developing, which does not appear likely at this time. A few showers are possible at KPOU tonight as well, but unlikely to have intensities that result in vsby restrictions below what will already be seen in BR. Conditions are expected to improve Saturday after daybreak as the strong June sun angle promotes diurnal mixing. The persistent light southerly flow may delay improvement at KPOU until later in the morning or during the afternoon. A thunderstorm or two cannot be ruled out as instability builds tomorrow afternoon, but lack of forcing will greatly limit coverage. Have kept previous forecast`s PROB30 mention for TSRA during the afternoon. Winds tonight will be light and variable. Southerly winds around 5 to 10 knots will develop Saturday by late morning into the afternoon. Outlook... Saturday Night: Low Operational Impact. Slight Chance of SHRA...TSRA. Sunday: Moderate Operational Impact. Chance of SHRA...TSRA. Sunday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Monday: High Operational Impact. Definite SHRA...TSRA. Monday Night: Moderate Operational Impact. Chance of SHRA. Tuesday: Moderate Operational Impact. Chance of SHRA. && .FIRE WEATHER... Increasingly warm and humid weather along with the threat for showers and thunderstorms through the weekend as a couple of low pressure systems impact the region. Temperatures will rise above normal by Fathers Day before a cold front approaches Sunday night into Monday. Relative humidity values will increase to near 100 percent tonight, drop to 55 to 75 percent on Saturday, recover to 90 to 100 percent Saturday night, and drop to 55 to 80 percent on Sunday. Winds will be south at 5 to 10 mph this evening becoming light and variable overnight, south at 5 to 10 mph on Saturday, light and variable Saturday night, and south at 10 to 15 mph on Sunday. && .HYDROLOGY... Our weather will be unsettled through at least early next week as a couple of low pressure systems impact the region. Humidity levels will be on the increase with high precipitable waters values moving on Sunday into at least Monday. Storms will be capable of producing locally heavy downpours which could lead to some minor flooding of low lying and poor drainage areas. Rainfall amounts will be variable and be dependent on where the showers and thunderstorms occur although most if not all areas will receive well over an inch of rain by early next 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. && .EQUIPMENT... KGFL airport observation continues to experience intermittent communication issues. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...IAA/BGM/11 NEAR TERM...IAA/BGM/Thompson SHORT TERM...IAA/11 LONG TERM...Speciale AVIATION...Thompson FIRE WEATHER...IAA/BGM/11 HYDROLOGY...IAA/BGM/11 EQUIPMENT...
Area Forecast Discussion
National Weather Service Gaylord MI
1145 PM EDT Fri Jun 16 2017 .UPDATE... Issued at 1021 PM EDT Fri Jun 16 2017 Diurnally-driven convection that develop across mainly NE Lower Michigan this afternoon/evening has greatly diminished and pushed east of our CWA late this evening thanks to sunset. Our CWA remains largely precip-free at this hour. However...a look at upstream radars KGRB and KMQT shows another convective complex working its way thru Wisconsin and Western Upper Michigan along and inverted trough axis coincident with an instability axis associated with low pressure centered over the Central Plains. Short term models suggest a general diminish in intensity as this convection pushes eastward into our CWA overnight. This seems reasonable given a projected diminishing trend to instability and 850 mb theta E. This notion matches well with the latest Day 1 Outlook from SPC which now has all of Michigan in general thunder. Have made some upward adjustments to POPs and timing of precip into our CWA overnight based on latest observed and model data. && .NEAR TERM...(Tonight through Saturday) Issued at 357 PM EDT Fri Jun 16 2017 ...Increasingly unsettled... High impact weather potential...lingering thunderstorms into early evening. Thunderstorms chances increasing again into Saturday. Low pressure is slowly progressing across far northern Ontario, with weak w to sw low-level flow into northern MI. Abundant surface heating and lake breezes are contributing to deep convection, most of which is in the expected locales (ne lower), but some of which is not (near Elk Rapids earlier). With surface pressure lowering in the Plains states, southwest low-level flow will increase into the region. That is coincident with still relatively low 500mb heights thanks to the closed 500mb low in northern Ontario, and an occasional shortwave moving in from the west. This is an increasingly favorable set-up for showers/storms. Tonight...spotty convection will persist for several more hours, especially in ne lower MI, and in western Chip/Mack (thanks to upstream activity in central upper MI). Indications of small hail/brief gusty winds with this activity, and a cell in ne Otsego Co got close to svr levels, but didn`t quite get there. HRRR has occasionally been arguing for activity in parts of WI to cross Lake MI into nw lower MI, but that lake is still awfully cold for surface-based convection to survive that trip. Will have some small evening pops near Lake MI in response. Showers and a few storms will increase from w to e overnight, as increasing sw flow feeds elevated convection. Nothing svr expected for the nighttime hours. Min temps upper 50s to mid 60s. Saturday...mid-level backs further wsw as a trof digs into the northern Plains. That will further amplify low and mid-level moisture transport northward. Ability to see substantial destabilization this far north looks to hindered by significant cloud cover, and the highest svr threat looks to be well-placed downstate. However, we will be entering a better set-up for healthy rainfall amounts as the day proceeds, with K indices pushing into the mid 30s, and PWATs in excess of 1.5 inches (especially in the se). Will attempt to portray some up-to-half inch QPF amounts in afternoon, particularly near Saginaw Bay (with heavy rain threat persisting into Sat night, see below). High likely pops in order in most places - it will /not/ rain all day, but likely will at some point. Max temps mid 70s to around 80f. && .SHORT TERM...(Saturday night through Monday) Issued at 357 PM EDT Fri Jun 16 2017 ...Thunderstorms possible Saturday night and Sunday, Showers Monday... High Impact Weather Potential...Marginal Severe risk into Saturday evening. Pattern Synopsis/Forecast...The sfc low and 500 mb shortwave trough moves into the Upper Great Lakes and continues the thunderstorms over the region into Sunday morning. Heavy rain is possible with the system as the Pwat is between 1.00" and 1.5" by Sunday morning as the 500 mb low rotates over Lake Superior. As the 500 mb shortwave moves out of the region and the 500 mb low moves east of Lake Superior a strong dry tongue moves into N lower and looks to stop any rain and convection, until late in the day as the 850 mb moisture moves back into the region with falling 850 mb temperatures. This should produce self destruct sunshine, and isolated to scattered showers. This will diminish into the evening with the loss of day time heating. Monday as the 500 mb low continues to rotate into the vicinity, it continues to cool the region and more self-destruct sunshine develops along with scattered showers. Primary Forecast Concerns...Saturday afternoon/evening SPC has the area of along and south of M-55, This looks like it would be the best for the system as the 500 mb jet streak moves into the region, with the RRQ of the jet over areas south of the forecast area. So main concern is if the jet moves a little more north, and helps to kick off more thunder, and possibly heavy. The other issue is heavy rain...which is possible with the high pwat values and the decent lift as the jet streak moves through. .LONG TERM...(Monday night through Friday) Issued at 357 PM EDT Fri Jun 16 2017 High impact weather potential...None. A somewhat zonal flow pattern remains in place across the CONUS with an anchoring long wave around 165W. Pattern is still expected to become more amplified and "troughy" across the Great Lakes heading through the weekend and the first half of next week as short wave energy pushing through the PAC NW today dumps into the upper Midwest/Great Lakes region late in the weekend. Pattern change will accompany a fairly strong surface low and cold front that swings up through the Great Lakes Saturday night/early Sunday...although recent model runs have backed off on the strength of that system. Following the weekend system...temperatures still look to take a dip below normal for much of next week...particularly the first half of the week as core of single digit 850 MB temps slide through. Daytime instability showers also still a good bet through at least Tuesday. Wednesday now holds promise for the best weather day of the week as we get brief intervening surface high pressure moving through and moderating temperatures. But then...another stronger weather system will bring shower/thunderstorm chances back into the forecast to finish up the work week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 1145 PM EDT Fri Jun 16 2017 Scattered to numerous showers and thunderstorms will develop from west to east overnight...with good chances of convection continuing on Saturday as an inverted trough slides thru Michigan. Overall conditions will remain VFR thru the TAF forecast period...but may briefly drop to MVFR within any heavier shower/storm activity. Light/variable winds overnight will become SW AOB 10 kts on Saturday. && .MARINE... Issued at 357 PM EDT Fri Jun 16 2017 Relatively light sw winds are expected into early Sat night, as low pressure gradually transits far northern Ontario. Winds/waves will remain below advisory criteria. Somewhat gustier west winds Sunday as a cold front goes thru, but only an outside chance that an advisory will be needed. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MLR NEAR TERM...JZ SHORT TERM...JSL LONG TERM...TBA AVIATION...MLR MARINE...JZ
Area Forecast Discussion
National Weather Service La Crosse WI
650 PM CDT Fri Jun 16 2017 .SHORT TERM...(This evening through Saturday) Issued at 235 PM CDT Fri Jun 16 2017 At 2 PM, a short wave trough moving through northwest Wisconsin was producing scattered showers and storms across central and northern Wisconsin. This system will move east across northern Wisconsin and be located in western Upper Michigan by this evening. As this occurs, a dry line will settle south toward the Interstate 90 corridor. Dew points will be in the mid and upper 50s north of the dry line and in the lower and mid 60s south of it. As temperatures climb into the lower to mid 80s this afternoon, the 0-1 km mean layer CAPES will climb into the 1500 to 2500 J/kg range south of the Interstate 94. This CAPE will be building ahead of an approaching short wave trough (currently located over western Minnesota). The CAM models are in good agreement thunderstorms will develop across east-central and south-central Minnesota between 16.19z and 16.21z. The latest RAP suggest that there will be sufficient deep shear that they will quickly develop into supercell thunderstorms and then as their cold pools coalesce the 0-3 km shear would favor a line of storms to move through east and southeast through the area. The main severe weather threat with these storms will be large hail and wind through 16.23z, and then evolve into primarily a wind threat which would last through 17.03z. While there is a severe weather threat across the entire area, the greatest chance looks to be along and south of the Interstate 90 corridor where the instability will be the greatest. For Saturday afternoon and night, a stronger short wave and surface cold front will be moving through the region. Like the past couple of days, the best instability will be well south of our forecast area. However, there will still be 1000 to 2500 J/kg 0-1 km mean layer CAPE from northeast Iowa into southwest and central Wisconsin. There may be sufficient deep shear for a few supercell storms to develop. Both the HRRR and ARW suggest this possibility. Meanwhile the NMM would suggest that these storms would develop across east-central Iowa, northern Illinois, and southeast Wisconsin. If this does occur, the primary severe weather threats would be large hail and damaging winds. There was a slight shift southward in the latest SPC Day 2 Outlook and this seems realistic. .LONG TERM...(Sunday through Friday) Issued at 235 PM CDT Fri Jun 16 2017 In the wake of this system, a much cooler air mass will move into the region. 850 mb temperatures will fall into the 7 to 9C range by Sunday afternoon and remain there for much of Monday. As a result, high temperatures will only range from the upper 60s to mid 70s. With 950 to 800 mb lapse rates over 8 C/km and 0-1 km mean layer CAPES up to 1000 J/kg, scattered diurnally driven afternoon and evening showers and thunderstorms will be possible across much of the Upper Mississippi River Valley. On Wednesday and Wednesday night, another short wave trough will move through the region. While the GFS and ECMWF are still differing on the amount of instability ahead of this system, there looks to be sufficient shear for the potential of supercell development. This system will have to watched over the next several days. From Thursday into Friday, the models hint at additional short wave troughs moving along the US/Canadian border, but there has been little consistency in the timing of these system. Due to this, there is a broad brush of showers and thunderstorms chances during this time period. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 650 PM CDT Fri Jun 16 2017 Thunderstorms will continue at the TAF sites through early evening. Expect large hail and wind gusts of 40 to 60 kts possible in any severe storms. Also, anticipate IFR conditions in any steadier rains or storms. The strongest storms will push east of the TAF sites by late evening. && .CLIMATE... Issued at 235 PM CDT Fri Jun 16 2017 The first half of June was the warmest at both La Crosse WI and Rochester MN. Through the first half of June, the average temperature at La Crosse Regional Airport was 75.3 degrees. This was 8.3 degrees warmer than the 1981-2010 average and the warmest first half of the June. The previous record was 73.3 degrees in 2005. Records date back to 1873. Meanwhile during this same time period, the average temperature at Rochester International Airport was 72.5 degrees. This was 7.1 degrees warmer than the 1981-2010 average and the warmest first half of the June. The previous record was 71.1 degrees in 1956. Records date back to 1886. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Boyne LONG TERM...Boyne AVIATION...Wetenkamp CLIMATE...Boyne
Area Forecast Discussion
National Weather Service Duluth MN
1053 PM CDT Fri Jun 16 2017 .UPDATE... Issued at 1053 PM CDT Fri Jun 16 2017 Showers and a few thunderstorms continued across portions of the Northland, with the stronger showers/storms occurring over northern Wisconsin. A low level boundary and low level FGEN continues to focus additional development over northwest Wisconsin and we have adjusted POPs through the evening to account for the latest radar trends. Much of the guidance is in agreement that overall the coverage of the showers/storms will diminish overnight then increase through the day Saturday. UPDATE Issued at 653 PM CDT Fri Jun 16 2017 Please see the 00Z Aviation Discussion below. && .SHORT TERM...(This evening through Saturday) Issued at 330 PM CDT Fri Jun 16 2017 A closed upper low over northwest Ontario will drift around this same area this afternoon through Saturday. Embedded vorticity maxes in the fast flow aloft will move over the forecast area through Saturday. A longer wave trof will extend from the upper low southwest into South Dakota by Saturday afternoon. This leads to periodic episodes of showers and isolated to scattered thunderstorms for late this afternoon through Saturday. First group of showers and storms was forming along a surface boundary from north of McGregor through southern Bayfield county to Hurley, WI, which shows up nicely on KDLH radar. Additional showers were beginning to pop along the Borderland. Virtually no CAPE along the international border, so expect showers only. These pieces of energy and their resultant shower and thunderstorm activity will be difficult to time, although the HRRR has been doing a decent job. Followed the HRRR and blend of other convective allowing models for the rest of the afternoon and tonight. Min temps will be in the 50s. The best opportunity for more widespread showers and storms will be on Saturday. This is when a long wave trof will cross into the Dakotas by the afternoon. A more vigorous shot of vorticity moves into the base of the trof and will generate a more generous area of showers and storms by afternoon across the region. There will be some showers in the morning, especially north of U.S. Highway 2 in northeast Minnesota. With more cloud cover anticipated, max temps will be a bit cooler with upper 60s along the Borderland, to the upper 70s over the southern tier of the region. .LONG TERM...(Saturday night through Friday) Issued at 330 PM CDT Fri Jun 16 2017 Our upper low pressure system for tonight and Friday exits off quickly to the east Friday night and Saturday, allowing a ridge of high pressure to build into the area for Saturday night. This leaves us with some potential for below freezing temperatures for both Friday night and Saturday night. Have concerns for cloud cover and wind both nights which could keep frost from forming or keep temperatures a little too warm, but the potential is there and we will need to reevaluate again tomorrow. Saturday looks cool and mostly cloudy. Sunday our next weather system takes shape over southern Saskatchewan and moves east across Canada, pulling some warmer temperatures into the area for both Sunday and Monday and our frost/freeze concerns diminish for both days. Monday night through Tuesday night we have another upper level wave moving across the area, which interacts with a decent baroclinic zone lying over the forecast area. This should bring another round of precipitation to the area, with rain south and either a rain/snow mix or all snow north. Wednesday we have another ridge building into the area with enough cold air to give us more potential for frost/freeze concerns. Thursday and Thursday night the models are hinting at another wave moving across the Midwest which should bring us some rainfall, but there are some pretty significant differences in the models this far out and have kept pops low for now. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 653 PM CDT Fri Jun 16 2017 VFR through the TAF period, however there may be some periods where MVFR ceilings/visibility develops if a shower/storm passes through a terminal. Cyclonic flow will continue across the Upper Midwest with a cutoff low rotating across Ontario. The combination of the cyclonic flow and diurnal heating has brought scattered showers and storms. Expect this activity to diminish once the sun sets. Have held off in including any thunder mention at TAFs this evening, as SPC mesoanalysis has MLCAPE off to the south, but think the best chance of a thunderstorm this evening would be at KHYR. Think there is a low chance of fog development at HIB/INL/BRD, but suspect there will be too much cloud cover for good radiational cooling. A trough will dig into the Northern Plains on Saturday. This combined with heating will result in scattered showers and storms developing across the region per the latest guidance. Uncertain on how widespread thunderstorm activity will be at this point, so have left in as VCSH. && .PRELIMINARY POINT TEMPS/POPS... DLH 54 73 52 65 / 50 70 60 40 INL 51 68 50 60 / 40 60 40 40 BRD 55 76 53 65 / 60 70 60 20 HYR 56 78 55 66 / 60 70 70 50 ASX 55 76 52 66 / 50 70 70 60 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ UPDATE...Melde SHORT TERM...GSF LONG TERM...LE AVIATION...WL
Area Forecast Discussion
National Weather Service Sioux Falls SD
630 PM CDT Fri Jun 16 2017 .SHORT TERM...(This evening through Saturday) Issued at 239 PM CDT Fri Jun 16 2017 Main forecast concerns are the potential for severe weather late this afternoon and evening and then the larger area of rain on Saturday. For this afternoon, the severe weather threat appears to confined south of Hwy 18 in Iowa as well as far southeast South Dakota and northeast Nebraska. There is a strong jet streak moving into eastern South Dakota this afternoon and this will interact with a convergence line across north central Nebraska to initiate convection. 0-6 km shear profiles are very favorable for the development of supercells with 0-6 km bulk shear from 40 to 50 kts. The limiting factor is moisture. Dew points over northeastern Nebraska are in the upper 50s and lower 60s. With southerly flow, this drier air will advect northeast into northwestern Iowa this afternoon behind accas that developed late this morning. There is deeper moisture south of I80 where GOES-16 imagery shows PWs approaching 1.5 inches and surface dew points near 70 degrees. There is high confidence convection will develop across northeastern Nebraska. However, supercell motion will be southeast and any storms developing near O`Neill should remain south of Sioux City and Wakefield. The question is if there will be additional development north of the NE/SD border as the boundary moves toward Sioux City and if enough moisture will exist to support strong updrafts. At this time, do expect at least a few storms to develop - perhaps as far north as Hwy 18 near the IA/SD. However, the limited moisture is expected to keep to most storms from becoming severe with the greatest risk being a microburst with winds up to 60 mph due to the evaporative cooling within the dry boundary layer. If enough moisture can get into the Sioux City area by late afternoon, then supercells capable of producing 2+" hail will be possible. However, current trends in dew points as well as HRRR indicate that this threat is low. Convection should move east of the area prior to midnight tonight. A strong will wave will approach from the northern Rockies late tonight and Saturday. Instability is rather limited due to limited moisture and much cooler temperatures. However, this wave will have a lot of ascent associated with it. Therefore begin to increase the chance of showers and thunderstorms by late tonight and spreading into southwest Minnesota and northwestern Iowa by early Saturday afternoon. There is just enough instability to keep thunder in the forecast and expect that many areas north of I-90 will see at least light rain. With the limited moisture generally expect rainfall amounts to be less than 0.25". Evaporative cooling and cloud cover will result in highs 10 to 20 degrees cooler than today - generally be in the 70s with coolest readings in southwestern Minnesota. .LONG TERM...(Saturday night through Friday) Issued at 239 PM CDT Fri Jun 16 2017 Should see precipitation wane through the evening Saturday night, as upper trough and associated cool front exit to our east. In the wake of this system, cool air will briefly settle into the region Sunday, with highs only in the 70s for most areas. The cooler air lingers across the northeast into Monday, as the upper trough swings slowly east through the Great Lakes, while a building upper ridge over the Rockies begins to bring warmer air back into southwest parts of the region. Various weak waves slide across the region through this upper trough, bringing light precipitation chances to the Northern Plains Sunday, and to a lesser degree again Monday afternoon. A northern stream wave crosses the Canadian Rockies and flattens the ridge through the middle of next week, which brings a transition to quasi-zonal flow across the northern CONUS through the upcoming work week. Vast differences among the models regarding the strength of this initial wave, and thus in their depiction of how far south into the Canadian Prairies/far northern CONUS it will dig by mid to late week. Stronger solutions bring another push of cooler/more stable air into the region by Thursday, while weaker solutions maintain near to above normal temperatures and greater instability. With the uncertainty in solutions at this range, did not alter broad model blend for pops or temperatures at this point. However, did limit thunder potential to just slight chance/isolated range, with the exception of Wednesday when there is better consensus in the models allowing instability to build ahead of the wave. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 623 PM CDT Fri Jun 16 2017 Will linger a VCTS group for the KSUX TAF site for one hour, ending it at 01Z as the TSRA complex continues to move toward the southeast. There will be some isolated to scattered TSRA in northwest IA through perhaps 01Z to 02Z, but that activity will likely not be severe at this point and will not affect the KSUX TAF site. Otherwise, VFR should be the primary category through the TAF period, with some scattered TSRA activity possible on Saturday over KFSD and KHON as an upper air disturbance and cold front swing through. Any TSRA activity on Saturday will likely not be very strong. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ SHORT TERM...Schumacher LONG TERM...JH AVIATION...MJ
Area Forecast Discussion
National Weather Service Lincoln IL
913 PM CDT Fri Jun 16 2017 .UPDATE... Issued at 913 PM CDT Fri Jun 16 2017 Made some adjustments to the forecast grids for the overnight time period to slightly increase PoPs. Radar mosaics and Clean IR loop showing several clusters of storms/MCSs from southern WI to central IA and southeast NE. The MCS in southwest IA and NE has a definite southeastward propagation to it, while the weaker cluster of storms in northern IA is moving more eastward. Many of the convective allowing models, are bringing at least a portion of the convection into central Illinois. The HRRR, and to a lesser extent the 00z NAM, are indicating showers and a few thunderstorms pushing into the IL River Valley around 3 am. After that time the convection scatters out more and weakens. Thus, went with likely PoPs for the IL River valley and 30-50 PoPs in the rest of central and eastern IL. Parts of southeast IL may stay rain free overnight, with any lingering showers holding off until Saturday morning. && .SHORT TERM...(This evening through Saturday) ISSUED AT 313 PM CDT Fri Jun 16 2017 Partly cloudy afternoon today going into a rather stormy start to the weekend. Some cu out there, but so far convective activity has been limited for the bulk of Central IL. Some showers and thunderstorms over the southern portions of the state along the Mississippi River Valley, but otherwise quiet for the afternoon. Expected scattered development of some convection later this afternoon in the east. Weak pops continuing through the evening hours, increasing after midnight, particularly in the NW. Overnight convection will receive an assist by the LLJ ramping up ahead of the next system. Wave of energy rippling through the region tomorrow as well as warm advection will assist in a general lifting of the airmass and scattered showers and thunderstorms will be possible throughout the day. However, the chances will increase into the afternoon/evening hours as a front draws closer to the NW. .LONG TERM...(Saturday night through Friday) ISSUED AT 313 PM CDT Fri Jun 16 2017 Details for the frontal passage tomorrow night are difficult to come by as the models are still having issue with the speed of the system, as well as the volume of convection during the day providing a wrench to instability parameters later in the evening. As a whole, the forecast remains much the same...hot and muggy until a frontal passage late Saturday night brings a different airmass into the Midwest. A weakened area of low pressure has remained over south central Canada for several days now. Early Saturday an impulse moves on the Pac NW coast, rippling into the region and digging back in over the northern Plains and Upper Midwest, resulting in a more amplified flow pattern. Associated surface system develops over the Northern Plains and becomes better defined as it moves into the Great Lakes region, dragging a cold front behind it for Saturday night. Uncertainty still clouds how deep the system, the time of arrival, as well as the impact of prefrontal showers and thunderstorms for the afternoon that would impact the development of the evening storms along the boundary. Should the heat of the day remain largely untouched through the day on Saturday, the convective potential will lend itself to some severe storm development tomorrow night, with some decent sheer into the midlevels. SPC has left much of Central IL in an Enhanced Risk as a result. Temperatures at 850mb drop a few degrees for a slightly cooler wrap up to the weekend and beginning of next week. Behind Sat night/ Sun morning storms, models dry out and cool off briefly...at least until midweek. At the end of the forecast, significant WAA pattern setting up in the midlevels resulting in a warm up and return of pops for midweek. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 650 PM CDT Fri Jun 16 2017 Isolated convection is expected in east and southeast Illinois early this evening, but far enough away from any of the TAF sites to mention VCTS. Will be watching the convective systems blossoming into western Iowa for the potential to slide ESE into central Illinois late tonight. The short range convective allowing models don`t have the best handle on this, although the HRRR does show the remnants of an MCS moving into central IL in the 07-11z time frame. For now will mention VCTS in the TAFS after 07z and through daybreak, but with VFR ceilings. VFR conditions will prevail through much of Saturday. However, with a tightening gradient and decent mixing will increase the winds and add gusts at most location from late morning through the afternoon. Kind of tough to time the movement of t-storms toward the TAF sites late in the afternoon due to the movement of a weak front from the west and associated upper level forcing/shear. The best bet is after 22-23z, so will introduce at least VCTS at the TAF sites along and west of I-55. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Miller SHORT TERM...HJS LONG TERM...HJS AVIATION...Miller
Area Forecast Discussion
National Weather Service Indianapolis IN
657 PM EDT Fri Jun 16 2017 .UPDATE... The Near Term and Aviation sections have been updated. && .SYNOPSIS... Issued at 327 PM EDT Fri Jun 16 2017 High pressure ridge over the southeast U.S. will retreat to the east. Low pressure moving into the central plains will track across the upper midwest and Great lakes over the weekend. A cold front will push across Indiana by Sunday. Dry and slightly cooler weather will occur early next week after the weekend. But warmer weather and a chance of more storms will return by the middle of next week. && .NEAR TERM /Tonight and Saturday/... Issued at 657 PM EDT Fri Jun 16 2017 Based on latest HRRR runs and ongoing convective development, have brought the slight chance of thunder down into Indy metro for a few hours this evening. Storms appear to be forming on a weak convergence zone but are significantly diurnal in nature, which will limit their persistence into the overnight. Previous discussion follows. Issued at 327 PM EDT Fri Jun 16 2017 Radar indicated scattered thunderstorms across the middle Mississippi valley...southern great lakes and and south central Ohio. Models and water vapor satellite indicate a weak upper disturbance will move east across northern Indiana early this evening. Air mass over central Indiana has been capped and nothing has developed in our area so far. The rapid refresh model indicates there could be an isolated thunderstorm over northern and far western sections early this evening...then mostly dry weather will occur overnight with perhaps a slight chance of more storms reaching western sections towards daybreak. Will keep areas from INDY and to the southeast dry overnight with slight chance POPS north and west early this evening and slight chance POPS mainly west again late tonight. On Saturday there will go with chance POPS most areas by afternoon as another weather disturbance moves our way along with a bit more moisture. Lows tonight will be in the upper 60s to near 70 and highs Saturday will be in the middle 80s to around 90 which is close to a MOS blend. && .SHORT TERM / Saturday night through Monday/... Issued at 327 PM EDT Fri Jun 16 2017 Forecast challenges focus on storm chances Saturday night into Sunday as a very warm and unstable airmass will occur ahead of a cold front approaching from the northwest. Models indicate two waves of convection with one moving our way and weakening late Saturday and then a stronger one moving our way Saturday night. Air mass will be quite unstable with MU capes in excess of 2000 J/KG and models hint at a possible MCS Saturday night. Will go with likely POPS over northern sections and high chance POPS elsewhere Saturday night. Sunday could be wet as well as a cold front moves through our way. Will go with likely POPS south and chance POPS elsewhere Sunday with storms ending from the northwest late Sunday. Other than a slight chance of storms south Sunday evening...mostly dry and cooler weather will occur Sunday night and Sunday as high pressure behind the cold front builds east. The blended MOS gives 20 percent POPS far northeast late Monday...but all in all expect dry and cooler weather to the the rule. Stayed close to a MOS blend on temperatures most periods with lows in the lower 70s Saturday night and lower 60s Sunday night. Highs will be in the lower 80s Sunday and upper 70s to near 80 Monday. && .LONG TERM /Monday night through Friday/... Issued at 225 PM EDT Fri Jun 16 2017 Dry weather will start the long term for Monday night in the wake of a frontal passage. Then there will be only small or slight chances for thunderstorms until Wednesday night while broad high pressure is in place from the Plains through the Ohio Valley. From Wednesday night on better chances for thunderstorms will arrive as the upper pattern flattens out and a a couple of surface system approach and move through the area. Temperatures will climb by a degree or two each day, with highs reaching the middle 80s to around 90 by Friday and low Friday morning getting back into the upper 60s to lower 70s. && .AVIATION /Discussion for the 17/00Z TAFs/... Issued at 657 PM EDT Fri Jun 16 2017 VFR through the period outside of potential convective impacts. Widely scattered storms this evening will impact LAF and may briefly impact HUF/IND. Impacts are too uncertain for explicit mention, but may include brief forays into MVFR territory if convective cores move over the airfields. Otherwise, patchy light fog will be possible tonight where rain falls but unlikely to have significant impacts. Somewhat more widespread convection is possible very late in the period, but again, too uncertain for much more than vicinity mention. Winds will be around 10KT or below throughout the period, generally out of the south. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH/NIELD SHORT TERM...JH LONG TERM...CP AVIATION...JH/NIELD
Area Forecast Discussion
National Weather Service Northern Indiana
656 PM EDT Fri Jun 16 2017 .SYNOPSIS... Issued at 336 PM EDT Fri Jun 16 2017 Showers and thunderstorms will remain possible prior to the passage of a cold front on Sunday. The best chance for organized thunderstorms, including the risk for severe weather, is Saturday night into early Sunday. Lows will be in the 60s tonight with temperatures warming back into the middle 80s Saturday. && .SHORT TERM...(This Evening through Saturday) Issued at 336 PM EDT Fri Jun 16 2017 Second of 2 MCV`s working across the area, sparking little more than a few showers at this time. As it works into eastern areas can`t rule out a rumble of thunder as it encounters a narrow axis of better instability. Behind the area, satellite would tend to suggest a good deal of subsidence. However, SPC meso data shows at least some instability still lingering back in portions of Illinois where temps have recovered into the middle 80s and dewpoints were slightly higher. Vis sat showing a few cu starting to pop which could indicate some isol shower/storm development could edge in towards evening as advertised by a handful of CAMS as a weak disturbance noted on water vapor edges in. Not comfortable dropping pops entirely so leaning towards 20 to 30 pops through 03Z then a lull until later tonight when remnants of upstream convection may be arriving, which brings a set of challenges all it`s own for Saturday. CAMS showing several scenarios with upstream convection, any of which are plausible ranging from a dying area of showers and storms approaching overnight into early Saturday to showers and storms diving southwest of us along what may be best instability and moisture gradient. As a result have kept highest pops NW late tonight into Sat AM with more changes likely to come as complex evolves to the west. Going into Sat afternoon, should be at least some clearing in the wake of morning activity that will allow destabilization across the area. Forcing mechanisms may exist in the form of leftover outflow boundaries or even a MCV that could impact the area during the afternoon, which could bring isol to sct storms. Confidence low in how this will unfold so have opted to broadbrush pops in mid chance range for the afternoon. Focus on greatest severe threat will be into long term period. && .LONG TERM...(Saturday Night through Friday) Issued at 336 PM EDT Fri Jun 16 2017 Threat for severe weather still looms with only subtle changes to SWODY2 with Enhanced risk now bumping up against our western counties. For the time being, think this was a good move as several factors still remain in question for severe threat, including those mentioned in short term discussion. Have generally held with likely pops much of Saturday night given gambit of solutions in terms of timing, possibly as early as 3Z to as late as 7Z for arrival in the west. Main mode of severe should be damaging winds, which could be on the stronger side if well established cold pool and forward propagation of the line hold together which is normally a challenge into the less favorable convective window of the overnight hours. However, as eluded to in past discussion dynamics and potential organization may very well negate these issues. For more details on the mesoscale setup, refer to DY2 outlook which matches close with thinking here. Otherwise, cold front will sweep through by Sunday with cooler and less humid air arriving through mid week. Warm front will begin to edge back north for the second half of the week, slowly increasing both temps and humidity. No major system, but arrival of warm front could bring some precip chances as well as hit or miss convection south of it into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 651 PM EDT Fri Jun 16 2017 Main concern this taf cycle is TS potential. Sct TS forming along east-west boundary extending from east central IL into west central OH early this eve. Some newd drift of these cells is fcst by latest HRRR suggesting they could impact FWA before diminishing with loss of heating later this eve, though questionable if sufficient instability farther ne to sustain storms, thus, just planning to mention VCTS til 02z in FWA taf. S-SW flow will strengthen overnight as a convectively enhanced shrtwv moves into the mid MS valley. This should destabilize airmass across nrn IN and allow ongoing storms over nrn IA/srn MN to track se across nrn IN Sat morning. Airmass across our area will grdly destabilize again in wake of morning convection Sat, but lack of sgfnt forcing supports leaving TS out of fcst for the aftn, though an isolated storm psbl. Outside of TS, VFR conditions expected through the period. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Fisher SHORT TERM...Fisher LONG TERM...Fisher AVIATION...JT Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion
National Weather Service Jackson MS
921 PM CDT Fri Jun 16 2017 .DISCUSSION... A very impressive mesoscale convective vortex is driving a severe bow echo rapidly southward through southern portions of the ArkLaMiss late this evening and have extended the severe thunderstorm watch in time to account for this. The HRRR has had trouble keeping up with the accelerated convective evolution with previous runs showing the MCV would maintain convergent boundaries and additional storm development through much of the night...but the latest trends are for complete overturning of the airmass and less chance for renewed convection late tonight on the back side of the system. Have tried to reflect latest trends in this forecast update...but rain chances for after midnight are of lower confidence given inconsistencies in guidance. In any case, expect the threat for severe storms to end with passage of the current bowing line. Will just need to watch for any renewed convection and locally heavy rain potential...especially on the upstream side of system due to very heavy rain that fell earlier today. /EC/ && .AVIATION... 00Z TAF discussion: The threat for SHRA/TSRA will linger well into the night as extra lift associated with a disturbance helps to maintain convection beyond sunset and this will keep the threat for IFR category ceilings/vsby relatively high at most sites. Outside of the SHRA/TSRA, expect mainly VFR conditions with some potential for early morning fog. Additional storms could redevelop for locations mainly east of the GWO/JAN corridor Saturday afternoon. /EC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 70 91 74 91 / 85 26 14 13 Meridian 69 90 74 91 / 84 28 17 24 Vicksburg 74 92 74 91 / 57 23 12 9 Hattiesburg 71 90 72 91 / 85 26 16 27 Natchez 73 90 73 90 / 63 21 11 16 Greenville 69 91 75 91 / 48 20 10 10 Greenwood 69 91 75 90 / 70 23 12 12 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
Area Forecast Discussion
National Weather Service Jacksonville FL
931 PM EDT Fri Jun 16 2017 .UPDATE... Overall things have settled down this evening with just a few showers popping up over the interior areas this evening. The HRRR model is interesting as it is bringing a boundary across the Suwannee Valley overnight with a few showers and possibly an isolated thunderstorm popping up between midnight and sunrise. the line moves from the Suwannee River and Madison County near midnight to Trenton and Macclenny by sunrise. Otherwise a humid summer night in store for the area with some light fog near sunrise where the heavier rain fell today. && .AVIATION... looking at VFR conditions at all fields overnight with a scattered deck developing between 1300-1500 utc tomorrow. && .MARINE... the Bermuda Ridge axis will remain southeast of the region through Saturday. This will keep a south to southwest flow across the areas with a southeasterly sea breeze developing during the afternoon and evening from the seabreeze. Surface ridge will lift north across the waters Sunday into early next week produce a south to southeast flow. Winds will be slightly stronger during the afternoon and evening hours due to the seabreeze but winds area expected to remain below headline criteria. Seas generally less than 4 feet. Scattered showers and thunderstorms. Rip Currents: A low end moderate risk along the northeast Fl beaches through Saturday due to a long period swell. Risk may become enhanced early next week as flow will tend to become more south to southeast. && .PRELIMINARY POINT TEMPS/POPS... AMG 71 92 73 92 / 40 30 30 20 SSI 75 88 77 86 / 30 30 30 20 JAX 72 91 74 90 / 40 40 30 40 SGJ 72 89 74 86 / 40 30 30 40 GNV 71 91 72 91 / 30 40 20 50 OCF 71 90 73 90 / 20 40 20 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Sandrik/Shuler/Corless
Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
1000 PM CDT Fri Jun 16 2017 .UPDATE... Updated grids and forecast package to carry thunderstorms a little deeper into the overnight hours and to mention gusty winds with thunderstorms as MCS continues to move southward across central Mississippi. Storms are about to enter northern portions of the area, but reflectivity levels have dropped quite a bit in the last 30 minutes. HRRR and RAP were indicating quick weakening, but won`t let down our guard quite yet. 35 && .PREV DISCUSSION... /issued 500 PM CDT Fri Jun 16 2017/ SHORT TERM... A complex of storms has developed across northern and central Mississippi this afternoon in association with a small vorticity maximum in the NNW flow aloft. Short term guidance indicates the storms will continue to the Gulf Coast this evening, primarily from 0 to 5Z this evening and generally across eastern portions of the area. The storms are expected to weaken through the evening, but will still be advancing through an environment with about 2000 J/KG mixed layer CAPE. The primary threat would be strong downbursts within some of the storms though hail is still possible as well. Closer to the coast there is probably still a more stable layer around 800 mb, which will aid in the eventual weakening of the storms. Overall high pressure across the region this weekend will keep rain chances after tonight low, though diurnal scattered showers and storms will still be possible with the sea and lake breeze. Temperatures will be a bit warmer with daytime highs near 90. LONG TERM... Early next week the central Gulf Coast will be in between the strong ridge anchored over the desert southwest and the western edge of the Bermuda high to the east. Well to the south a tropical low pressure is likely to develop near the Yucatan, which is the feature currently being monitored in Tropical Weather Outlooks. This surface low will develop only gradually the next several days, with no rapid strengthening expected. By Tuesday this broad low pressure will be in the south central Gulf. The upper level pattern over the Gulf allows for a wide range of track possibilities next week due to the lack of strong steering flow and the weak nature of the low, which is represented by the spread in guidance. At the moment general westward movement toward south Texas or the northern portion of the Mexican coast seems most plausible. Movement too far to the northwest into the ridge is unrealistic. The development and track of the tropical feature will continue to be monitored for potential impacts the central Gulf Coast. For example, if the low drifts further into the central Gulf an increase in moisture and rain chances would be possible for south LA and MS later next week. Krautmann AVIATION... VFR conditions are expected to prevail through this evening. The main concern and uncertainties are with regards to TSRA threats and timing. Greatest confidence where scattered or greater coverage of TSRA occurs is at KMCB this evening, so included a TEMPO group. Did not include mention of TS in the remaining TAFS at this time, but that may need to be added later as development trends become better defined. MVFR CIGS should return after 08-09z tonight through 14-15z Saturday mainly at KBTR, KHDC and KMCB. Isolated to locally scattered TSRA are expected again mainly in the afternoon on Saturday, so later TAF issuances may need to add mention. 22/TD MARINE... A broad area of high pressure system will remain centered to the east of the coastal waters through the weekend resulting in generally light winds and seas with the exception of in and near thunderstorms and associated outflow boundaries. An area of low pressure is expected to move into the southern Gulf of Mexico early next week. Refer to the latest Tropical Weather Outlook from the National Hurricane Center for additional details. At this time, the model blends used brings easterly winds up to near 15 knots or slightly higher over southern waters by late Monday through Wednesday morning before veering to southeast near 15 knots over most coastal waters Wednesday afternoon. Wave heights will be dependent on how fast and how strong either a tropical wave or cyclone develops along with the size and distribution of the wind field. Current forecast brings wave heights up to 6 to 7 feet late Monday into Tuesday, but all aspects of the forecast are likely to change with future developments in the lower Gulf. 22/TD DECISION SUPPORT... DSS CODE...Blue. DEPLOYED...None. ACTIVATION...None. ACTIVITIES...Monitoring river flooding. DECISION SUPPORT SERVICES (DSS) CODE LEGEND GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH VISIBILITY EVENT YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES RED = FULL ENGAGEMENT FOR MODERATE TONIGHT RISK SVR AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL SIGNIFICANCE && .PRELIMINARY POINT TEMPS/POPS... MCB 71 91 73 90 / 60 30 10 20 BTR 74 90 75 91 / 40 20 10 20 ASD 75 90 75 89 / 60 30 20 30 MSY 75 89 75 89 / 50 30 20 30 GPT 76 88 77 87 / 60 30 20 30 PQL 74 88 75 87 / 60 40 20 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Louisville KY
746 PM EDT Fri Jun 16 2017 .Forecast Update... Issued at 740 PM EDT Fri Jun 16 2017 Made some minor adjustments to fog grids this evening through tomorrow morning based on latest model data. Latest trends seem to indicate that the fog potential may not be as high as previously thought, mainly due to dry air aloft and increasing southwesterly winds around 1kft that could potentially mix down to the surface. Best chances for patchy fog still look to generally south and east of the Bluegrass Parkway. Still planning on keeping the forecast dry for the evening, though am closely monitoring some small potential for very isolated showers/storms in northwestern portions of the CWA in southern Indiana. Some isolated showers and thunderstorms have begun firing off near the KVWX radar within the past hour or so and are slowly drifting toward Dubois/Perry counties. Several outflow boundaries are being picked up by radar/satellite as well. A quick mesoanalysis of the environment reveals 1500-2000 J/Kg MUCAPE across portions of southern Indiana, however, capping is quite strong and should keep a lid on most convective activity. If the isolated activity holds together, it should arrive into Dubois/Perry counties shortly after 02z. Will continue to monitor and update the forecast if it appears activity will hold together into the late evening hours. && .Short Term...(This evening through Saturday night) Issued at 230 PM EDT Fri Jun 16 2017 Latest preliminary GOES-16 derived precipitable water indicates a narrow swatch of dry air over the region, stretching from central Tennessee into Central Kentucky and then northeast to western New York. This area is not moving much today, and AMDAR and current RAP soundings show a subsident airmass in place across much of the region. Thus have generally fair weather cumulus forming out there. Temperatures are warm under the good insolation, with dewpoints in the upper 60s to around 70, so the day is not overly perfect, but typical for mid June. Only other concern then would be chances for fog overnight. A look at the GFS flow aloft indicates a weak disturbance moving through the Midwest to our north tomorrow afternoon, and then another one approaching the region late Saturday night. Precipitable water is expected to increase between now and Saturday night as more moist air pushes against our dry plume. Usually the edges of these dry plumes are where convection gets fired during daytime heating, so the current forecast for isolated to widely scattered pops across southern Indiana seems reasonable, with just isolated chances along the I-65 corridor. Warm temperatures should go for that mostly dry forecast, with highs Saturday reaching the 90s for many locations. Saturday night, the hi-res models, and to a lesser extent the coarser ones, bring in a decaying line of storms ahead of a cold front late. So here again will keep in the higher rain chances over the northwest, southern Indiana, with a gradient into south central Kentucky. Night time lows will depend on how quickly, or if, showers/cold pool get into the region. .Long Term...(Sunday through Friday) Issued at 230 PM EDT Fri Jun 16 2017 The timing of precip Sunday will depend greatly on when/if rains move through here Saturday night. Long-wave troughing aloft will provide some energy for new development, with cold mid-level lapse rates. Any boundary from the late Saturday night development could serve as a focus as well for new development during the afternoon. As for severe risk, the wind profile shows more shear potential than with the last few days worth of convection, especially over the northern half of the area. Temperatures for highs here again will depend on location of these boundaries. One other thing to note, precipitable waters from the models look awfully high, especially given that the GFS/NAM/GEM all would argue for record values for mid June. Still expect at least above average moisture into the region, so heavy rainfall will come with any storms that fall. By Monday, most of the precip should be just over or east of central Kentucky, with the trough axis aloft swinging through here and ridging trying to build in for midweek. Models have been struggling with bringing in (or not) a frontal boundary and rains Tue night/Wed and then beyond that we are back to a series of disturbances moving through the flow making timing best rain chances difficult this far out. Will keep up with the slight chances for Wednesday and limit peak rain chances the rest of the work week to that 20-30 percent range. Monday should be the coolest day of the extended, and then we`ll flip back to above normal by mid week, though again they will depend on what should happen with that midweek system. && .Aviation...(00Z TAF Issuance) Issued at 700 PM EDT Fri Jun 16 2017 Latest guidance beginning to back off on fog development near the LEX/BWG terminals tomorrow morning due to drier air aloft and 10- 15kt southwesterly winds 1kft above the surface with the potential that some of it could mix down. Not completely sold that they will remain fog free tomorrow morning, so will at least include a TEMPO group for MVFR visibilities tomorrow morning. Otherwise, expect some strato-cu to redevelop across the region tomorrow morning and afternoon. Expect most of it to be in the VFR range, but could see some high-end MVFR cigs near BWG briefly tomorrow morning. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...DM Short Term...RJS Long Term...RJS Aviation...DM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
846 PM CDT Fri Jun 16 2017 .UPDATE... 846 PM CDT Near term focus remains on thunderstorm development and trends overnight. While low levels will slowly stabilize after sunset, forcing from approaching mid-level disturbance and strengthening mid-upper level westerly wind fields may continue to support the potential for a few strong/severe storms into northwest and north central IL through the late evening/early overnight hours. SPC has expanded the current day 1 slight severe risk into the northwest part of the cwa with the 01Z update. Region radar depicts a fairly large area of convection currently occurring across western Wisconsin, with evidence of an MCV northwest of Madison. High-res CAM`s have indicated the potential for southeastward development into northwest IL since this afternoon, and while 00Z DVN sounding supports RAP initialized mesoanalysis data with 2300 J/Kg MUCAPES, there has been a lack of cumulus development since this afternoon east/south of the could/rain shield which has entered northwest IL with the MCV. Recent HRRR runs (00Z particularly) seems to be catching on, and focuses additional development across eastern/northeastern Iowa over the next few hours where warm advection ascent ahead of mid- level short wave over western IA and trailing flank of the WI MCV circulation is already beginning to initiate storms west of Waterloo. Expectation is that these storms will fill in towards northeast IA, and eventually move into northwestern IL by midnight. Greatest potential for strong/severe storms will be across our far west/northwest cwa where higher MUCAPES exist, with a gradual weakening expected overnight as storms spread farther east. Main threats would be winds where cold pool consolidation occurs or mesoscale rear inflow develops, with the strongest cores perhaps capable of producing marginally severe hail. Remnant MCS rains may linger into early Saturday morning especially across eastern parts of the cwa, with lingering cloud cover and subsidence behind the system initially stabilizing the atmosphere for the morning hours. Ratzer && .SHORT TERM... 125 PM CDT In The Near Term... Forecast confidence on timing of individual shortwaves and better periods of thunder in the near term is not super high, but there will likely again be several periods of generally weakening showers and embedded thunder. The first shortwave in fast moving flow aloft is currently across southern MN and moving into WI and will just have some clouds, with showers north of our area. The next more organized wave across the Dakotas and into Nebraska will interact with an increasingly unstable airmass and likely lead to a complex of showers and storms late this afternoon and evening. Guidance is mixed as to how much of this first area will impact the area, but the northern half of the area stands the chance of another round of showers and embedded thunderstorms. KMD Tonight Through Saturday Night... Continue to closely monitor the potential for severe weather across the area/region on Saturday, especially Saturday evening, which could include a higher end wind and hail threat. Thunderstorms appearing to be highly probable throughout the day Saturday into Saturday night area wide. This includes a period of thunderstorms possible Saturday morning, scattered development possible by mid/late afternoon, and then more widespread and strongest thunderstorms by the evening. Once again, this includes the entire area. However, varying guidance continues to bounce around with exactly how the day will unfold. This includes some uncertainties regarding each period of possible thunderstorms, with which the Saturday morning development could have an impact on instability and development later in the day. Surface pattern appearing really messing during the day Saturday, likely from guidance trying to resolve this deep convection produced from this large/strong system expected to move through region. So, at this point will stay focused on a more synoptic scale approach and what makes sense conceptually given what latest guidance is depicting. Early in the period, zonal flow in place will likely continue to usher in upstream short wave energy over the central CONUS. A likely scenario from this support would be for continued thunderstorm development over the northern Plains late this evening, with these thunderstorms then likely following instability axis into northern Illinois by late tonight but more so early morning Saturday. What more than likely will happen will be what occurred last night with thunderstorms moving into our area but on a diminishing trend. However, forcing appears to be stronger which could support more widespread coverage and with instability also slightly higher, these thunderstorms may have a chance to stay stronger. These thunderstorms and potential strong/severe threat of mainly hail with a low threat of wind could linger through mid morning, before departing to the east. Setup would then favor clearing skies with sunny conditions then supporting a destabilizing atmosphere into the afternoon. There doesn`t appear to be strong support for any widespread thunderstorms by midday or early afternoon. However, could see possibly needing to monitor for isolated development during this time though, on any lingering outflow boundaries. This could be especially the case by mid/late afternoon as multiple pieces of guidance depicting some isolated development. Confidence is low on exact placement, but anything which were to develop could pose a severe/hail threat. Most locations will likely be dry for most of the afternoon though, with the more widespread development not arriving until the evening hours. By late afternoon into the early evening, large scale ascent really ramps up across the region. This is in response to digging upper level trough with strong upper jet moving overhead, and with increasing mid level energy and flow. This increase in upper level flow, which will include flow at 500mb approaching 70KT or higher, will support bulk layer shear quickly ramping up by early evening to more than enough values supportive of organized development. Attendant surface low expected to quickly deepen during this time, with overall setup then favoring an increase in thunderstorms. This is as most guidance is in agreement with moderate/strong instability to be in place during this time. However, situation gets really complicated, with low confidence still in place for placement of this low and general surface pattern. Increase in coverage likely during this time/evening, with main development expected to be in and around surface low and associated boundaries. Once again, confidence as to where this main development will occur is low at this time. This is key as do think initial thunderstorms will have the potential to be discrete, with the quickly increasing wind fields. Soon there after, setup would then favor a transition over to more linear convection. A wind threat, quite possibly higher end, would then be the more probable hazard in the evening. Given the extent of the potential instability, large hail will also be possible, along with heavy rainfall and localized flooding. With low confidence as to the surface pattern and initiation, don`t want to really put any focus on any one area across the CWA. At this time, these hazards appear possible across the entire area. The threat of storms and these hazards could continue through late in the evening and quite possibly into a portion of the overnight hours, before exiting the area. Area depicted by SPC`s SWODY2 including the elevated risk area still appears valid given the potential setup and also the uncertainty. After whatever precip develops and then evolves tonight into early Saturday morning, a more refined threat area including the main threats should hopefully be realized. Rodriguez && .LONG TERM... 138 PM CDT Saturday night through Thursday... Following the frontal passage Saturday night, a cooler and drier airmass will settle into the region. The upper level low responsible for the active weather will remain parked across south central Ontario for several days. This will lead periods of clouds and showers in the cyclonic/northwest flow around the southern periphery of the low across northeast Illinois and northwest Indiana. A more organized wave on the back side of the low will move through on Tuesday as the low ejects to the north and east which could give the showers a bit more kick and also lead to some thunderstorms in the northwest flow pattern. Mid week there will be a transition period as the low moves east. Low level flow will turn southerly and advect a steadily warmer and more moist airmass northward as the upper level jet shifts north. An active zonal jet stream will bring additional shortwave energy toward the region leading to additional thunderstorm chances in the later Wednesday/early Thursday time frame. KMD && .AVIATION... For the 00Z TAFs... 627 pm...Main forecast concern is thunderstorm potential late this evening through sunrise Saturday and again late Saturday afternoon into Saturday evening. Area of convection along the MN/IA border is moving generally east with weaker showers/convection extending south. Short term guidance suggests this activity may begin to build southeast over the next few hours following a better instability axis into far northern IL. Confidence this will occur is only medium but added tempo thunder for this potential later this evening. If this does occur...an outflow boundary is likely to produce gusty northwest winds. A second area of convection developing over eastern NE is expected to move southeasterly this evening with new development to the northeast that will likely arrive in a weakening phase during the predawn hours. Its possible this activity may end up prevailing showers with some embedded thunder but confidence regarding its weakening is low. Opted to include tempo thunder around sunrise for this potential. A cold front will move across the area Saturday night and thunderstorms are expected to develop ahead of this cold front late Saturday afternoon and quickly spread across the terminals Saturday evening. Confidence for thunderstorms during this time period is high but coverage remains uncertain with perhaps scattered coverage across the terminals and a more solid line south of the terminals. Still a bit early for specifics but thunder mention late in the afternoon at rfd and during the 24-30 hour period of the ord taf is reasonable with this forecast but changes to timing/coverage is possible with later forecasts. South/southwest winds will diminish under 10kt with sunset and remain southerly overnight. Convection may allow winds to turn more southeast or easterly at times overnight. Winds will turn back south/southwest by mid/late Saturday morning and forecast soundings would suggest gusts in the 20-25kt range are possible Saturday afternoon. cms && .MARINE... 138 PM CDT Several periods of thunderstorms overnight tonight into early Saturday and again Saturday evening will likely lead to periods of occasionally stronger winds over the lake and nearshore then depicted in the text forecasts, with potentially damaging winds during the Saturday night time frame. Those with outdoor recreation plans on the lake should stay abreast of severe thunderstorm forecast for later Saturday and Saturday night. Also of note, thunderstorms last night kicked up waves to 3 ft or so in the nearshore zones with outflow ahead of and with the storms. Similar storms may occur in the early morning Saturday time frame. Low pressure over Ontario will move to James Bay early Sunday morning. Southwest to south winds 10-20 kt continue through Saturday. A secondary low pressure trough dips south over the western Great Lakes Saturday night while strengthening into Sunday as it moves northeast into Ontario. Winds become westerly to 25 kt on Sunday behind the low. High pressure will build over the plains early this week and spread over the Ohio Valley Monday night/Tuesday. A high pressure ridge will pass over the western Great Lakes Wednesday and winds become southerly (to 25 kt or so) behind it Wednesday night/Thursday ahead of another modest low that will move into the Great Lakes region. KMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Omaha/Valley NE
804 PM CDT Fri Jun 16 2017 .MESOSCALE DISCUSSION... Issued at 747 PM CDT Fri Jun 16 2017 Supercell storms have congealed into an outflow dominant line. Intense winds have occurred with the storms over the western part of the Omaha metro area. Winds at WFO Valley gusted to 88 mph at 736 PM CDT. Storms are going to continue driving south-southeast at 40 mph. Storms are following gradient of the downdraft CAPEs around 1200 J/KG. Storms will continue producing wind damage as they drive southeast in easteren Nebraska. Leading edge of storms should reach a Nebraska City-Shenandoah, IA line around 840 PM CDT. In addition, QCLS tornadoes are possible on the leading edge of the line of storms as they move southeast. && .SHORT TERM...(Tonight through Monday) Issued at 336 PM CDT Fri Jun 16 2017 Severe thunderstorm threat through this evening remains the primary forecast concern. Atmosphere was taking its time recovering this afternoon from Thursday evening convection, however the process was slowly occurring. Mid level shortwave as shown by enhanced water vapor imagery was progressing into central Nebraska at mid afternoon, ushered along by 90kt upper level jet knifing into the western Dakotas. Surface front was sharpening in central Nebraska as well, with 60-70F dew points streaming north ahead of it into south central Nebraska. 850 moisture was also slowly increasing in this area as per RAP analysis, noted by 12C dew point temp just ahead of surface front. Northward extent of moisture return was less than previous model solutions, but HRRR continued to initiate convection in north central Nebraska, and that has occurred as of 330 PM. As convection moves across northeast Nebraska as per HRRR, strongest activity is likely to develop/move southeast with time this afternoon and evening into plume of higher moisture and instability across south central and southeast Nebraska. However high effective bulk shear is in place now and will continue across all of eastern Nebraska into southwest Iowa through the evening. Thus even where instability is somewhat lacking, severe storms are still possible. While hail is likely with any storms given combination of shear and instability, wind threat is also enhanced where inverted-v soundings are prevalent in our north, and cold pool acceleration in the south. There is a tornado risk as well, especially with initial development of storms over the southern half of the state where low level moisture is in place, and also as supercellular structures maintain themselves as scattered line progresses southeast and interact with mesoscale surface boundaries. Expect line of storms to progress south and east of our area late this evening, leaving most of the rest of the night dry. Another stronger mid level trough is still forecast to drop into the Dakotas Saturday, enhancing lift over cooler air behind surface front. Thus scattered showers are possible during much of the day in our north. To the south, most model output suggests cold front and thus surface instability will be well to our south during the afternoon. However there is plenty of spread suggesting southeast Nebraska and southwest Iowa may be close enough for strong storms during afternoon heating. A slight to enhanced risk is outlined by SPC Day 2 outlook there, but will have to see how far front progresses before getting overly concerned. Otherwise cooler conditions are forecast Saturday and Sunday when northerly low level flow keeps highs in the 70s to lower 80s. Highs rebound back into the lower 80s on Monday when westerly low level flow brings slightly warmer air into the region. .LONG TERM...(Monday night through Friday) Issued at 336 PM CDT Fri Jun 16 2017 Northwesterly mid level flow will begin the longer term period, with a gradual return to a more zonal pattern by the end of the week. No major storm system are forecast to affect our area during this time, so precipitation chances will be confined to impulses rolling through the faster mid level flow. Timing of these features is impossible to pin down this far out, and model output offers varying opinions on timing and magnitude. Suffice it to say there will be at least random chances for convection beginning Tuesday night and continuing through Friday. Temperatures are likely to rebound back into the upper 80s to lower 90s most spots Tuesday through Thursday, and perhaps a bit cooler on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 628 PM CDT Fri Jun 16 2017 Line of convection in northeast Nebraska will affect the KOMA TAF site between 01Z and 04Z with IFR conditions and will have the potential for wind gusts over 50kt and large hail. Storms will likely just skirt KLNK area, but could produce similar IFR/wind/hail between 02Z and 04Z. Storms are south of KOFK and will remain that way. North winds will overtake all TAF sites later tonight and will continue into Saturday with mainly mid and high level clouds. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ MESOSCALE...Smith SHORT TERM...Dergan LONG TERM...Dergan AVIATION...Dergan
Area Forecast Discussion
National Weather Service Blacksburg VA
735 PM EDT Fri Jun 16 2017 .SYNOPSIS... High pressure offshore will maintain a warm and humid airmass across the region into this weekend. A weak cold front will approach the area from the northwest this weekend with added showers and storms likely into early next week. && .NEAR TERM /THROUGH SATURDAY/... As of 710 PM EDT Friday... Mesoanalysis at 23z showing high pwats in place and slow moving cells. Despite lack of deep convection, the precip rates are higher than indicated by radar, and given slow movement are causing some isolated low lying and street flooding issues. There is a decent theta-e ridge/converge zone from the NC foothills into SE WV. Short range models especially the latest HRRR hang onto this activity in the same general area through late evening. At the same time, convection in the NC piedmont is expected to send enough of an outflow to develop showers/storms over southern VA/northern NC by 03z, as forecast by the HRRR. Attm, favoring a demise of showers in the west as sun goes down, but think higher pops are more likely over the piedmont to foothills this evening. Given how coverage of showers/storms are, not organized enough to have any flash flood watches out. However, with high pwats, any slow moving storms, especially over urban areas will likely cause street flooding. Previous afternoon discussion... Radar continue to show scattered showers/thunderstorms with locally heavy rain. satellite imagery has shown extensive cloud cover most of the day and this has helped limit instability. While the environment remains marginally conducive for severe storms with modest CAPE values and weak shear supporting an opportunity for gusty winds, the main threat will be local flooding from storms with high rainfall rates that cluster/train over the same locations. While latest meso guidance is showing an opportunity for a resurgence of convection early tonight, will shade POPs toward a consensus and monitor closely. Expect some patchy fog again overnight, then another round of diurnal convection tomorrow as we remain in a warm, moist, and unstable airmass with broad synoptic ascent and weak shortwave energy streaming through a trof to our west. Temperatures will remain near seasonal norms with highs tomorrow generally in the low/mid 80s east of the Ridge, upper 70s/lower 80s west. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 310 PM EDT Friday... Subtropical plume of moisture will remain along the east coast through Monday. Strong upper trough and associated cold front will approach from the northwest Sunday and slowly cross the forecast area Monday. Squeeze-play between the cold front and lingering tropical plume will promote scattered to numerous showers/storms Sunday and numerous to widespread showers/storms Monday. Greatest threat from this sort of weather scenario is heavy rainfall, with high rain rates (3-5 inch an hour) which could easily result in actual amounts of 1-3 inches. Combination of strong diurnal heating ahead of the front and increasing upper level dynamics from the upper trough will also support the risk for severe weather, increasing winds aloft supporting organized deep convection with the potential for damaging winds. Temperatures and dewpoints through this period of the forecast will remain quite summerlike with humid/muggy conditions both day and night, temperatures in the 80s to near 90 for highs and 60s for lows. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 310 PM EDT Friday... The connection to the tropics is forecast to be interrupted Tuesday into Wednesday as a strong upper trough moves from the Great Lakes and into New England, clipping the Mid-Atlantic. This troughing should induce enough west to northwest wind aloft to suppress the deeper subtropical moisture to our southeast, helping to lower the overall PWAT. There is still some question as to whether we will have enough drying to totally suppress the threat for an afternoon shower/storm, but at the very least we should have more sun than clouds for mid-week with most of the CWA favoring the dry side of the forecast. Not until we get deeper moisture to return ahead of an approaching front toward the end of the week do pops substantially go back up. As such think this period of the forecast will be relatively rain free with forecast temperatures near normal for Tue/Wed...the trending 4 to 8 degrees above normal Thur/Fri. . && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 712 PM EDT Friday... We will see variable aviation conditions this evening and per High-res models appears better threat for convection will be toward Danville. As of this writing, BLF seems to be in line to have heavier showers and sub-VFR cigs/vsbys through 02z. With weak frontal boundary from Southern WV to Southside Va per sfc theta-e analysis focus stays in place through early overnight, especially east of the mountains. Will not get fancy with showers/storms and have VCTS or VCSH with tempo group early for DAN/ROA/BLF. Overnight is the cig/vsby issue and expect some low cigs/vsbys in this moist environment. Question is how low. Wx pattern suggest for more stratus than fog, so will hit LIFR cigs at all TAF sites. Fog will be around, especially higher ridges, and possibly LWB/BCB but overall IFR to MVFR vsby. Any fog/stratus will slowly dissipate Saturday morning and we will repeat the cycle of diurnal convection. Outside of thunderstroms winds will generally be light through the period. Extended Aviation Discussion... Very moist and unstable conditions combine with an approaching trof to keep convective activity, with a strong diurnal trend, in the forecast into the weekend. There will also be a trend fog fog/stratus development during the predawn hours. A better chance for more widespread showers and storms including sub-VFR looks to arrive on Monday with a surface cold front perhaps crossing the region. This will allow for extended periods of sub- VFR ceilings and visibilities. In addition, radiational late night/early morning fog will be on the increase. Appears will see drier conditions Tuesday/Wednesday but not completely free from a chance for showers. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH/MBS NEAR TERM...MBS/WP SHORT TERM...PM LONG TERM...PM AVIATION...JH/MBS/WP
Area Forecast Discussion
National Weather Service Shreveport LA
940 PM CDT Fri Jun 16 2017 .UPDATE... Only minor changes made to the ongoing forecast. Ongoing convection east of the forecast area has promoted cirrus blow-off to move across portions of southwest AR and northern LA, thus causing an update to the Sky grid. Elected to drop POPs to below mentionable levels across the northeastern zones a few hours earlier than expected tonight, given the aforementioned convection has been maintained east of the ARKLATEX. Otherwise, forecast is largely on track with another rather mild overnight /middle to upper 70s/ followed by another slightly above normal day tomorrow. && .PREV DISCUSSION... /issued 648 PM CDT Fri Jun 16 2017/ AVIATION... Vfr conditions areawide with s-sw winds 5 to 10 kts. Mvfr cloud decks to arrive into ne TX in low lvl sw flow by around 17/12z, and then quickly diminish with daytime mixing by 17/15-16z with mostly vfr skc as upper ridge increases over area. S-sw winds around 10 kts Sat aftn with a few higher gusts over mainly ne TX./07/ PREV DISCUSSION... /issued 226 PM CDT Fri Jun 16 2017/ DISCUSSION... Convection for the most part has developed just as expected with the more favorable storm track staying just northeast and east of our CWA where a weak disturbance in northwest flow is interacting with strong instability. Upper ridge is suppressing any thought of convection across the remainder of our region attm. Did keep slight chance pops going across our extreme northeast and eastern zones as a descent cu field was observed in afternoon VIS loop in the wake of the disturbance but even the more advantageous HRRR has now shifted late afternoon/early evening convection to our east before convection weakens with the loss of heating and instability. Not seeing much in the way of upstream disturbances embedded in northwest flow aloft as has been the case the last couple nights that could effect us late tonight or during the day Saturday so with a strengthening upper level ridge axis across our region, kept pops out of the forecast for Saturday. What will be on the uptick so to speak will be afternoon Heat Index values which will be just under Heat Advisory Criteria for portions of our region. The same will be true for Sunday but we reintroduce pops for late Sunday and especially Sunday Night into Monday along and ahead of an unseasonably strong cold front. Longwave trough will become rather stagnant to our south and east and should not influence our weather too much for Sunday but a digging upper level trough across the middle portions of the country will drag along with it a cold front which will begin knocking on Southeast Oklahoma`s door late Sunday Aftn and will be the trigger necessary for scattered late afternoon and especially evening convection. Upper level support does not warrant a widespread severe weather threat with this convection but cannot rule out an isolated strong to severe thunderstorm across Southeast Oklahoma or Southwest Arkansas Sunday Evening. The front will very slowly make its way towards the I-20 Corridor of Northeast Texas and Northern Louisiana by mid to late morning on Monday again with scattered convection possible along the boundary. The drier/milder air will lag the sfc boundary somewhat Monday Night but should begin to filter into our entire area during the day Tuesday with drier dewpoints and lower humidity values. We will continue to undercut blended model temperatures concerning overnight lows through much of next week given the drier post frontal airmass conditions. Needless to say, pops are near nil beyond Monday of next week but low level moisture should return quickly by late next week into next weekend and along with the moisture return will be a return to isolated to scattered convection. Thanks for the coordination today FWD...JAN...prelims to follow...13. PREV DISCUSSION... /issued 1145 AM CDT Fri Jun 16 2017/ && .PRELIMINARY POINT TEMPS/POPS... SHV 76 93 76 93 / 10 10 10 10 MLU 75 93 75 93 / 10 10 10 10 DEQ 72 94 75 89 / 10 10 10 30 TXK 75 93 76 91 / 10 10 10 20 ELD 74 93 75 91 / 10 10 10 10 TYR 76 94 76 93 / 10 10 10 10 GGG 76 93 76 93 / 10 10 10 10 LFK 74 94 76 94 / 10 10 10 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 29/07/13
Area Forecast Discussion
National Weather Service Tallahassee FL
920 PM EDT Fri Jun 16 2017 .NEAR TERM [Through Tonight]... This evening`s mesoanalysis showed the nearest organized convective cold pool along the AL-MS border. The latest HRRR runs initialized this feature well, and do not have it reaching our forecast area overnight. The MCS that moved through our forecast area last night really turned the troposphere over, leaving a warm, relatively dry pocket at around 925 mb and switching the lower tropospheric flow to a NW direction. This combination has significantly limited deep moist convection today as the NW sea breeze front got pinned at the coast for much of the afternoon. It was finally propagating inland this evening, but only a few storms have been able to develop in the marginal thermodynamics. This trend will continue through the morning. && .PREV DISCUSSION [740 PM EDT]... .SHORT TERM [Saturday Through Sunday Night]... Both the 00z ECMWF and 12z GFS are in fairly good agreement through early Sunday showing an elongated trough through the Central Gulf. Thereafter, their solutions diverge with the EURO showing the trough deamplifying with the Bermuda ridge and ridge over Texas bridging across the northern Gulf. The GFS shows the trough persisting through the short term and into the extended period. Both solutions would have a sharp contrast of impacts on our forecast due the prescience of a tropical disturbance over the northwest Caribbean Sea over the weekend. The building upper ridge would steer the system west or northwestward and well away from our CWA. The GFS shows a surface low along with a surge of tropical moisture lifting northward across the eastern Gulf late Sunday and Sunday night. Until then we should see less convection over the Tri-state region both Saturday and Sunday due to the influx drier air in the mid levels with forecast PW`s down around 1.4-1.5". Temps will be near seasonal levels. .LONG TERM [Monday Through Friday]... A lot of uncertainty in the extended forecast per above discussion on model differences. For now will lean toward the ECMWF solution which takes the tropical disturbance over the Yucatan Peninsula and across the Bay of Campeche through the week. Thus, for now expect a typical summertime pattern with diurnal convection with PoPs generally in the 30-50% range. Highs in the upper 80s to around 90 with lows in the 70s. .AVIATION [Through 00Z Sunday]... VFR conditions are expected to prevail through the majority of the period at all terminals. One exception could be around sunrise at TLH as winds become light/calm, and patchy fog could develop along with some scattered low clouds. Any fog will be short-lived during this time, and after it dissipates scattered clouds with light southwesterly winds are expected to prevail through the remainder of the period. .MARINE... Favorable marine conditions expected with light winds and low seas through Sunday night. Beginning Monday, winds and seas will increase to more moderate levels as a tropical disturbance moves into the southern or Gulf of Mexico. .FIRE WEATHER... No concerns. .HYDROLOGY... Scattered afternoon showers and thunderstorms are expected for the next several days. Rainfall accumulations will generally be around 1-2 inches through Sunday, but isolated areas could receive that in a single afternoon. Due to the scattered nature of the storms, widespread river flooding is not expected, however, isolated flooding will be possible. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 71 89 69 89 71 / 10 40 20 30 20 Panama City 76 85 75 85 75 / 20 30 20 20 20 Dothan 72 90 73 89 72 / 20 40 20 30 20 Albany 72 90 72 90 73 / 10 30 20 30 20 Valdosta 72 89 72 90 73 / 20 40 20 30 20 Cross City 73 88 71 90 73 / 20 40 10 20 40 Apalachicola 76 85 74 85 76 / 10 30 10 20 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Fournier SHORT TERM...Barry LONG TERM...Barry AVIATION...Lahr MARINE...Barry FIRE WEATHER...Fournier HYDROLOGY...Moore