Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/30/19

Area Forecast Discussion
National Weather Service Quad Cities IA IL
539 PM CDT Thu Aug 29 2019 ...00z AVIATION UPDATE... .SYNOPSIS... Issued at 236 PM CDT Thu Aug 29 2019 As of 230 PM, a few showers and isolated storms, leftover from the morning convection, were located between Fort Madison and Macomb. This activity will continue to weaken through the mid afternoon. Synoptically, a cold front stretched from NE Wisconsin toward Dubuque and then into south-central Iowa. This wind shift was apparent on visible satellite imagery as a narrow band of stratocumulus with embedded gravity wave features and was moving to the southeast. Also of note, there was a lack of agitated cumulus across Iowa and Illinois. Further south, into northern Missouri, a remnant outflow boundary from the morning round of storms was serving as a focus for deeper convection early this afternoon (south of the CWA). Low-level moisture return has been significant today on southwest winds with dewpoints reaching into the mid 60s to around 70 F. Temps have been held down across the south where the earlier complex of storms brought heavy downpours and widespread cloud cover. In this area, early afternoon temps were still in the mid 70s. && .SHORT TERM...(This Evening through Friday) ISSUED AT 236 PM CDT Thu Aug 29 2019 Late This Afternoon into Tonight SPC has maintained the Slight risk for severe storms over the SE two-thirds of the forecast area. Trends in surface and satellite observations and the latest hi-res models suggest relatively low storm coverage across our CWA into tonight. The stronger than expected morning storm complex may have had an effect on the magnitude of low-level convergence that was anticipated across central sections of the area this afternoon/evening. It also led to slow temp recovery and lower surface-based instability in the south. For these reasons, and based on consensus of the 12Z HREF members, it seems the most likely scenario for redevelopment would be across the south (along and south of highway 34). Yet this is even a low confidence outcome because the remnant outflow boundary has pushed to our south and southwest into north-central Missouri. The HRRR is the furthest south of the hi-res models with the convective redevelopment holding off until this evening near our southern border. But with the environmental setup of 2000-3000 J/kg surface-based CAPE and 40+ kts of effective shear, a few severe storms remain possible into early tonight. The main threats are localized damaging winds and large hail. The tornado risk remains very low at 2% per SPC`s outlook. Friday The northern fringes of a complex of rain and thunderstorms could clip the far south from the mid morning into the afternoon, with the brunt of this activity remaining into central Missouri. Have slight chances for rain and thunder along and south of highway 34 (west of Galesburg). Otherwise, for most of eastern Iowa and northwest Illinois, it will be a nice day with highs in the 70s. Uttech .LONG TERM...(Friday Night through Thursday) ISSUED AT 236 PM CDT Thu Aug 29 2019 Initial concern is the potential for rain and much below normal temperatures over the first half of Labor Day weekend. A warming trend is then likely going into next week with periodic systems bringing low chances for rain. The front making its way through the forecast area in the short term is expected to stall out in a west to east orientation from the Central Plains through the mid Mississippi Valley region Friday night. A series of mid level shortwaves are expected to interact with this baroclinic axis to spread rain along and north of the boundary, possibly affecting the forecast area Friday night into Saturday. 12Z models remain in poor agreement with just how far north any rain reaches, with the WRF/NAM now virtually dry over the forecast area through the weekend, while the ECMWF has nearly 1 inch of rain across our south through Saturday night. The GFS and Canadian are in between, with mostly light amounts, focused across the south. For now, the forecast maintains at last low chances for showers overspreading the south and southwest late Friday night with isolated thunderstorms. Rain chances Saturday are still higher in the south, but limited to moderate pops with QPF likely well below a quarter inch. Of possibly greater consequence for the start of the holiday weekend will be the cool temperatures due to extensive cloud cover and low level easterly flow out of the Great Lakes high. Lower dewpoints will lead to overnight lows in the 50s to lower 60s, while Saturday`s highs may only range from around 70 north to lower 70s south. The passage of an inverted trough Saturday night will be followed by rebounding high pressure, favoring a dry Sunday with at least partial sunshine. This should drive highs back into the mid to upper 70s. Rising 500 mb heights and the northward returning warm front will produce a warming trend for Monday going into Tuesday, driving highs back into the 80s. Low pops are kept for late Tuesday into Tuesday night, when the boundary may drift back southward across the area. This is followed by highs returning back to the 70s for Wednesday and Thursday, where there is another potential for showers and thunderstorms with the next cold frontal passage. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) ISSUED AT 538 PM CDT Thu Aug 29 2019 VFR conditions to persist at the terminals through the period in the wake of a cold frontal passage, and as high pressure builds in. Gusty westerly winds 10-20+ kts will diminish below 10 kts tonight while becoming northerly. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Uttech SHORT TERM...Uttech LONG TERM...Sheets AVIATION...McClure
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
634 PM CDT Thu Aug 29 2019 .AVIATION... All terminals are VFR and will remain that way through the evening. MVFR ceilings will develop in Austin and San Antonio overnight, but will only last for a few hours. They should rebound to VFR by around sunrise. DRT will be VFR through the entire period. Winds will be 10 kts or less from the southeast. && .PREV DISCUSSION... /ISSUED 247 PM CDT Thu Aug 29 2019/ SHORT TERM (Tonight through Friday Night)... The weather remains fairly quiet across South-Central Texas at the present hour. Skies are mostly clear across much of the area with a cumulus field across the eastern CWA. The vertical extent of the cu remains poor but latest runs of the HRRR continue to show some initiation of some showers and perhaps a thunderstorm around 3 pm and the current forecast handles this well. Most if not all of the activity should be diminished by 7 pm and did not mention any PoPs in the tonight period. Otherwise, lows tonight will be in the lower to middle 70s for most areas. The region will remain in a weakness aloft and additional isolated showers and storms will be possible tomorrow mainly across the the eastern half of the area in the afternoon. Highs tomorrow will be similar to that of today with highs in the middle to upper 90s. Some locations will likely flirt with the century mark once again. Tomorrow night is expected to be quiet with lows once again in the lower to middle 70s. LONG TERM (Saturday through Thursday)... Low rain chances will linger across portions of the area Saturday but things should dry out for Sunday as upper heights rise as the ridge slightly builds back in. The ridge is then expected to break down again by Tuesday and this will allow for low chances of rain to return to the forecast. Temperatures in the extended will remain above normal with highs in the middle 90s to 103 degree range. Lows will remain in the lower to upper 70s. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 76 97 75 97 74 / 10 20 - 20 - Austin Bergstrom Intl Airport 75 96 74 96 74 / 10 20 - 20 - New Braunfels Muni Airport 74 96 73 95 72 / 10 20 - 20 - Burnet Muni Airport 74 95 72 94 72 / 10 20 - 20 - Del Rio Intl Airport 76 102 76 99 75 / - 10 - 10 10 Georgetown Muni Airport 75 97 74 96 74 / 10 10 - 20 - Hondo Muni Airport 74 100 73 99 72 / 10 - - - 20 San Marcos Muni Airport 74 97 73 96 72 / 10 20 - 20 - La Grange - Fayette Regional 76 98 75 97 74 / 10 30 - 20 - San Antonio Intl Airport 76 97 76 96 74 / 10 20 - 10 10 Stinson Muni Airport 76 97 76 96 74 / 10 10 - 10 10 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Aviation...05 Short-Term/Long-Term...BMW Public Service/Data Collection...EWilliams
Area Forecast Discussion
National Weather Service Goodland KS
842 PM MDT Thu Aug 29 2019 .UPDATE... Issued at 841 PM MDT Thu Aug 29 2019 Cancelled the remainder of the severe thunderstorm watch for our forecast area as storms have moved out of the area. UPDATE Issued at 751 PM MDT Thu Aug 29 2019 Updated the forecast to remove the severe thunderstorms watch as storms continue to move out of NW KS into north central Kansas. && .SHORT TERM...(This afternoon through Friday night) Issued at 1230 PM MDT Thu Aug 29 2019 Overview: WNW-NW flow aloft will prevail over the region, on the NE periphery of an upper level ridge over the Desert Southwest. Today-Tonight: A weak SFC-H85 cyclone centered in extreme northeast CO at 17Z will track ESE into northwest KS this evening as a small amplitude shortwave in southeast Wyoming (per 17Z WV imagery and SPC Mesoanalysis) progresses ESE through southwest NE into north-central KS. Surface observations and radar data show a thermal/moisture boundary associated with the aforementioned cyclone stretching SW-NE from Burlington->Saint Francis->Trenton, extending N-NW from Trenton to Ogallala NE. HRRR simulated reflectivity forecasts suggest that isolated convection will develop along the SW-NE oriented TMB in northwest KS (perhaps just S or E of Goodland) ~21-22Z this afternoon, progressing east into central KS this evening (by ~03-04Z). Though convection may be somewhat disorganized in nature at onset -- very steep mid-level lapse rates (~9 C/km), 30-40 knots effective deep layer shear, moderate to strong instability (1500-3000 J/kg MLCAPE) and extreme DCAPE (1500-1800 J/kg) suggest a potential for isolated high- based supercells capable of producing very large hail and significant damaging wind, primarily in E|NE portions of the area late this aft/eve (23-03Z) -- when flow aloft /deep-layer shear/ strengthen in advance of the approaching shortwave. Thereafter, activity is anticipated to rapidly grow upscale and track E-ESE across central/eastern KS. Friday-Friday night: The convective forecast in this period will highly depend on mesoscale features emanating from convection developing over the region this evening/tonight (and the impact thereof on the thermodynamic environment over), the evolution of upstream convection over the northern Rockies (and it`s impact on downstream height/wind fields), and small amplitude tropopause disturbances (~250 mb level) progressing from the northern Rockies into the Central/Northern Plains via WNW/NW flow aloft. With this in mind -- significant uncertainty persists with regard to when/where convection may develop, let alone convective mode/evolution/hazards. .LONG TERM...(Saturday through Thursday) Issued at 200 PM MDT Thu Aug 29 2019 The main story with the extended forecast will be dry conditions and temperatures near to above normal. Saturday morning, the Tri-State area will be under northwest flow as an upper ridge over the Western U.S. slowly progresses eastward through the day. Temperatures may be hampered early in the day due to lingering clouds and showers, particularly in the northeastern part of the forecast area. Chances for precipitation are not great, but cannot be entirely ruled out as a shortwave trough exits the area. Highs are expected to be in the mid-70s to low 80s across the region. High pressure will become centered over the Four Corners region Sunday. The ridge will remain over the western half of the U.S. and the Central High Plains. Am anticipating a return to the 80s and 90s both Sunday and Monday as southerly winds help our temperatures. Models are showing an upper level trough coming ashore over the Pacific Northwest Monday morning. Both the GFS and ECMWF show a closed low developing and progressing eastward through the day. Do not anticipate an impact in the Tri-State region to start out the week. May have a weak low trying to form east of the Rockies on Tuesday. Weak convergence may be enough to kick off a stray shower or storm Tuesday evening, but at this point in time, confidence in this is very low. Shortwave trough may move through the region Thursday. Did mention slight PoPs as it moves through, but confidence is low at this time. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 522 PM MDT Thu Aug 29 2019 The 00Z TAF at MCK will be starting out with a strong thunderstorms moving across the site that will be moving out of the vicinity by 02Z. Conditions will be VFR and will continue VFR into Friday morning. After 14Z, lower clouds will spread across the region with MVFR conditions due to lower ceilings along with thunderstorms developing after 20Z. GLD will be VFR through about mid day on Friday. After 17Z, conditions will become MVFR due to lower ceilings moving in along with thunderstorms developing after 22Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...LOCKHART SHORT TERM...VINCENT LONG TERM...AW AVIATION...LOCKHART
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1002 PM EDT Thu Aug 29 2019 .SYNOPSIS... Northwest flow has set up behind a frontal boundary that moved offshore this morning. Temperatures tomorrow will actually warm a bit over today due to abundant sunshine before another cold front moves through tomorrow night. Temperatures will cool a bit for the weekend behind the front before rain returns by Monday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 10 PM Update... Clear evening is in progress. Temperatures are dropping steadily and made few changes to the going forecast. HRRR and NARRE-TL show more fog possible over Augusta and Rockland areas in addition to the Connecticut River Valleys and mountain valleys, so have added that to the overnight forecast, generally after 3 AM. 620 PM Update... Just a quick update to adjust temperatures. Should be a nice night with readings in the 50s areawide and dropping dew points. Previous discussion... The near term tonight looks to be rather quiet. Dewpoints behind this mornings frontal boundary haven`t really dropped too much. This will likely result in fairly mild overnight low temperatures in the 50s to lower 60s at the coast. Over the mountain valleys where temperatures will drop more, expect to see some patchy fog set up. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Valley fog over mountain valleys should burn off quickly tomorrow morning. Weak westerly flow ahead of an approaching cold front will allow temperatures across the region to climb into the 70s over the mountains, to mid 80s over southern New Hampshire. The cold front is expected to move through the region tomorrow afternoon and evening. The front has very little moisture associated with it and will likely pass as a dry front through most of the area. The best chance for showers and thunderstorms will be over the mountains, while the coastal plain will likely stay dry. Cooler and drier air moves in behind the front. The drier air should negate fog development Friday night as temperatures fall into the 40s to mid 50s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Ensemble and deterministic model solutions remain in decent agreement on the long wave pattern through early next week. Much of the forecast period consists of a broad low amplitude trough across the northern third of the CONUS with the exception of the Pacific northwest. By the end of the period...rising heights and an upper ridge over the western two-thirds of the CONUS with an upper trough stretching across the Great Lakes and northeast CONUS. With the mean jet position nearby or overhead we`ll see quick day-to-day changes in sensible weather as a series of impulses and weak surface systems traverse the area. In the dailies...a weak trough will cross northern and mountain sections Saturday with a few clouds and perhaps a stray sprinkle. High pressure follows for Saturday night into Sunday. The numericals have trended slower with the arrival of the next system on Sunday...with that weak system arriving with clouds and a more widespread round of convection for Sunday night and Monday. A cold front will bring more unsettled weather for Tuesday and Wednesday as it settles southward across the region. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term...Expect to see some IFR/LIFR cigs and vsbys over mountain valley areas in fog tonight, while coastal locations stay mainly VFR. VFR conditions should then dominate all locations for the remainder of the short term. Long Term... Sun Night - Mon...Areas of MVFR in SHRA/TSRA. Tue...Sct MVFR in -shra/-tsra. && .MARINE... Short Term...No flags expected. Long Term... Sat AM...SCAs possible outside the bays. Mon PM - Tue AM...SCAs possible outside the bays. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Hanes SHORT TERM...Pohl LONG TERM...Schwibs
Area Forecast Discussion
National Weather Service Wichita KS
633 PM CDT Thu Aug 29 2019 .SHORT TERM...(This evening through Sunday night) Issued at 408 PM CDT Thu Aug 29 2019 Complex scenario unfolding tonight and the next couple of days. A Flash Flood Watch has been issued. First will be the threat of severe weather tonight across central, south central, and southeast Kansas. Northwesterly flow is sitting overhead and a shortwave is on its way through southern Nebraska. Storms are expected to develop along an east-west oriented cold front this evening along the Kansas/Nebraska border. This cold front feeds into a weak sfc low currently near the KS/NE/CO border. Additionally, storms have initiated along the dryline extending south out of the sfc low and satellite imagery shows aggravated cumulus bubbling along the front. Very moist low levels and adequate heating today has contributed to a very unstable environment area wide. RAP sounds show impressive CAPE values (MU 5000, ML 4000) with very steep lapse rates nearing 8C/km in central KS and effective bulk shear of 30-35kts. DCAPE is equally as impressive with values near 1400 J/kg and with drier midlevels and increasing PWs of 1.5 to 2 inches. Storms that come through central Kansas before being a more linear complex will have the potential for significant hail of 2 inches and damaging winds 60-70 mph possible. As storms continue to grow upscale tonight expect the hail threat to dampen some and transition to a largely wind threat for the remainder of the night. While the threat of any tornados are low, there is decent storm relative helicity available (130 0-1 km SRH, 175 0-3km SRH) that could favor an isolated mesovortice in a bowing line. These storms are expected to quickly grow upscale into an organized MCS. Corfidi vectors would suggest this MCS initially move toward the southeast and then take more of a southward plunge. Meanwhile moisture transport is progged to increase considerably overnight with a strengthening southerly LLJ. The LLJ and better moisture transport are progged to veer slightly with time. This may create a secondary area of convergence along any potential outflow boundary and perhaps bring storm coverage farther west as the MCS backbuilds. Given forecast PWs of near 2 inches overnight expect torrential rainfall with these storms. Due to significant rainfall potential, combined with recent rainfall over the area, opted for a Flash Flood Watch across the warning area (less Russell and Barton Counties). Flash flooding and river flooding are likely and will need to be monitored overnight. Wherever the outflow ends up will likely be a focus for renewed showers and convection through the day tomorrow. Several models show lingering showers and storms across the area thus left a decent amount of pops in the forecast for this. Confidence then decreases somewhat for tomorrow night into early Sunday morning. Whether or not we recover from the MCS, and again where the outflow sets up, will impact where any convection sets up. Models are still not in agreement and may change drastically depending on the outcome of convection tonight. Will let the next shift take a look at tomorrow nights-sunday convection potential. Left QPF a shave on the drier side given uncertainty. Ridging will try to build back in during the day on Sunday and start to dry us out. Expect temps in the mid 80s and set up a decent week in the extended. .LONG TERM...(Monday through Thursday) Issued at 408 PM CDT Thu Aug 29 2019 Expect quieter conditions Labor Dy and throughout the the extended period. An upper ridge will be building overhead next week leaving the area dry and under general high pressure. Expect temperatures to remain around seasonable normal in the upper 80s and low 90s. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 627 PM CDT Thu Aug 29 2019 Main aviation concern will be overnight storms. Cold front currently extends from southeast Nebraska into far NW KS with a dryline extending south of KGLD. Storms have developed over SW Nebraska and far western KS along the front and dryline with this activity expected to continuing tracking south with some expansion expected as the low level jet cranks up this evening. Storms will be a good bet for most TAF sites overnight, affecting KICT and KCNU after midnight. Damaging straight-line winds and hail will be the main threats, along with very heavy rainfall. By sunrise, far southern and southeast KS should be the only areas still being affected by storms. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 69 83 67 83 / 60 50 60 60 Hutchinson 68 82 65 83 / 60 50 70 60 Newton 68 81 66 82 / 60 60 70 60 ElDorado 69 82 67 83 / 80 70 60 60 Winfield-KWLD 68 83 67 83 / 70 60 50 60 Russell 66 79 64 83 / 50 50 70 40 Great Bend 67 81 64 83 / 50 50 70 40 Salina 68 81 66 82 / 70 50 70 50 McPherson 68 81 64 81 / 60 50 70 60 Coffeyville 70 82 69 83 / 70 70 40 60 Chanute 69 80 68 82 / 70 70 50 60 Iola 69 80 68 82 / 80 70 50 60 Parsons-KPPF 69 80 68 82 / 70 70 40 60 && .ICT WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 10 PM CDT this evening through Friday afternoon for KSZ033-048>053-067>072-082-083-091>096-098>100. && $$ SHORT TERM...KMB LONG TERM...KMB AVIATION...RBL
National Weather Service Wilmington OH
949 PM EDT Thu Aug 29 2019 .SYNOPSIS... High pressure over the Tennessee Valley will give way to a weakening cold front dropping south into the Ohio Valley later tonight and Friday. A few showers and storms may accompany the front into portions of northern Indiana and Ohio tonight, and again on Friday afternoon and evening in southern Ohio and Indiana. Humidity will be more noticeable on Friday along and ahead of the front, with cooler and drier air spreading into northern Ohio behind the front. The front will stall and wash out near the Ohio River Friday night with weak disturbances shifting through the Great Lakes over the weekend keeping small chances of showers and storms in the forecast. && .NEAR TERM /THROUGH FRIDAY/... As the daytime hours have come to an end, FEW/SCT cumulus clouds have largely dissipated, with generally clear skies setting in over much of the ILN CWA. As the next few hours progress, however, this inactive pattern will begin to change. At the surface, a front is moving south through Michigan. Aloft, westerly winds are beginning to increase in magnitude. The first change this is leading to is an increase in mid level clouds across northern Indiana and western Ohio. As the night progresses, dissipating showers (leftover from the convection over Michigan) may reach the northern sections of the ILN CWA, prompting the continuation of the 20-PoP. Eventually, some low level clouds may also thicken up in this area going into tomorrow morning. Temperatures will be dependent on the wind and cloud situation, but this is clearly favoring warmer temperatures in the northwestern CWA, and better radiational cooling in the southeastern CWA. With KPMH already down to 61 degrees, min temps had to be lowered by a bit in the far east and southeast, accounting for current observational trends. Previous discussion > Afternoon visible satellite imagery shows just a few fair weather cumulus over the forecast area with light-moderate southwesterly flow as low level warm advection has commenced on the backside of Tennessee Valley high pressure. A plume of dense cirrus /convective debris/ was over Illinois drifting southeast, and a broken line of storms along a sharp cold front continued to be maintained across eastern Wisconsin. GOES-East water vapor loops clearly showed the parent shortwave trough crossing Lake Superior, accelerating ahead and away from the cold front which was sagging southeast toward lower Michigan. Thinking has cleared /somewhat/ on upstream convective evolution and rain chances for tonight. Earlier /29.00Z/ CAMS and longer lead HRRR runs had hinted that convection in eastern WI would intensify this afternoon/evening into lower Michigan and build quickly south into northern Indiana, before weakening as it spilled into the ILN CWA later this evening in west-central Ohio. The 29.12Z runs have shifted away from this thinking /and more in line with what the mass fields had suggested all along/ that the convection now in eastern WI would continue east/southeast into western lower Michigan where it will gradually weaken as it builds southeast toward Detroit/Toledo. Farther back to the southwest in western Illinois and northern MO, a robust MCS will develop and sag southward. As the parent shortwave trough pulls more northeast with time into southern Canada, the front will begin to slow as it approaches the ILN CWA toward sunrise. A rather decent low level jet /40kts at 2kft/ out of the west-southwest will cross the area overnight as the front approaches. There may be just enough isentropic ascent for parcels to reach an elevated LFC over our northern counties after midnight, but the low level jet isn`t overly convergent in our forecast area, and moisture transport magnitudes will be decreasing in time. Thus, maintained low overnight rain chances in the far northwest/north part of the ILN forecast area for any showers which can develop in this regime. A much milder night is expected with lows only falling back to the lower and middle 60s owing to continued low level theta-e advection on the inbound low level jet and slightly disturbed nocturnal boundary layer. && .SHORT TERM /FRIDAY NIGHT/... Friday is a little complex. Out of the large MO MCS overnight will evolve a rather defined MCV/vort max that will begin to drift only very slowly east with time given it will be well displaced south of the faster westerlies well to the north. The cold front entering the I-70 corridor in the morning will continue to slow as heights begin to rise both in response to large scale ridging building over the southeast CONUS, and downstream of the MCV over MO. The front will still represent a rather marked moisture gradient despite it really starting to decay /frontolysis/ as it sags underneath larger scale height rises. After a morning/early afternoon of scattered mid/high clouds from overnight convection to our west/north, the front will sag into southern Indiana and Ohio with a modest low level instability plume along/ahead of it as upper 60s dewpoints spread in along its length. Forecast soundings are largely in agreement of about 1000 j/kg of MLCAPE, with steep low level lapse rates but rather meager lapse rates aloft owing to the larger scale height rises. While low level flow will be very weak only slightly confluent/convergent in vicinity of the boundary, there should be enough push to the boundary and instability at peak heating to spark scattered showers and storms between 4P and 8P in a rather narrow corridor along the front. Where this occurs is in question - many of the 29.12Z CAMS/HREF members suggest this corridor will be on a Hamilton/Wilmington/Chillicothe corridor and then sagging slowly south. The 29.12Z NAM/ECMWF/ARW WRF are - and have been - consistent in being very limited on convective development in comparison through the evening with only the ECMWF showing some scattered storms mainly over southern Indiana into extreme northern Kentucky /the furthest south solution/. From purely a consensus/ensemble of a large number of models approach - the further north solution has the most support /and also from a standpoint of a slowing front into height rises/. So have focused the best rain chances near the GFS/CMC/HREF/CAMs mean frontal position which is little further north than NAM/ECMWF consensus. This is the same axis as previous shifts. But - to account for uncertainty - the forecast rain chances are much broader than what would otherwise be forecast if there were higher confidence on frontal location. Kept chances around 30-35%. Hazard assessment - the instability axis /regardless of its exact latitude/ will lie on the southern fringe of stronger westerlies over central/northern Ohio. Forecast soundings at CVG/ILN on Friday at 21Z-00Z suggest effective shears around 25-30kts, meager mid-level lapse rates, modest DCAPE and delta- theta-e values. Given an overall marginal thermodynamic/kinematic profile - think storms will largely be sub-severe, especially considering low level shear values are so weak and thus outflows will tend to undercut the updrafts rather quickly. If there were a damaging wind report or two, would think southeast Indiana would be most primed owing to a little better instability the further west you go. Once the threat for diurnally enhanced/frontally forced convection wanes by mid-evening, attention then turns to the approaching MCV later in the night. Upcoming forecasts may need to increase rain chances again later in the night in eastern Indiana/western Ohio as this features slowly moves close and increases flow to the point that some elevated showers develop toward daybreak near the Indiana/Ohio border, but not enough confidence in the forecast to insert these given quite a muted forcing signal. && .LONG TERM /SATURDAY THROUGH THURSDAY/... High pressure north of the forecast area will keep an east/northeast wind over the region Saturday. Upper level energy oriented sw-ne will combine with some lower level convergence to produce a chance of showers or thunderstorms through the weekend. The mean upper trough becomes quite flattened Sunday and shifts east. However, increased lower moisture and some potential differential heating during the day has a typical diurnal increase in thunderstorm threat lingering into Monday. Southwest flow will keep mid 60s dewpoints in the region early next week, and a weak cold front will pass by Tuesday night or Wednesday. Initial indications for this fropa are that it will be battling a dry airmass and be relatively rain-free. Temperatures will generally top out between 80 and 85 with little variability expected. Overnight lows will similarly be tied to between 60 and 65, a little warmer Tuesday night and cooler Wednesday night behind the dry fropa. Any shower or thunderstorm activity that develops this holiday weekend will likely be isolated to scattered in nature and sub- severe as Dorian puts the brakes on any upper level flow over the region, or at least removes the probability of a deeper trough from affecting us. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... VFR conditions should generally continue through the period. Cumulus clouds will dissipate this evening, and there may be a slight decrease in the speed of the SW / SSW winds, though they should remain in the 5-10 knot range overnight. There is a very small chance of some showers making it into KDAY/KCMH/KLCK late tonight, but it is more likely that there will just be an increase in low and mid level clouds. It is also not out of the question for a brief period of MVFR ceilings in the 09Z-15Z time frame at these TAF sites (less likely further south). At KLUK, some MVFR (to possibly IFR) fog is expected early tomorrow morning. Tomorrow, there does appear to be a chance of thunderstorm development during the afternoon. This appears most likely at KCVG/KLUK/KILN, where a VCSH has been included in the TAFs. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau NEAR TERM...Binau/Hatzos SHORT TERM...Binau LONG TERM...Franks AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Northern Indiana
800 PM EDT Thu Aug 29 2019 .SYNOPSIS... Issued at 757 PM EDT Thu Aug 29 2019 An upper level system tracking across the Great Lakes will drag a cold front across the region tonight. This system will be accompanied by a low chance of showers and thunderstorms this evening into the early overnight hours. Low temperatures tonight will range from the upper 50s to middle 60s. Mainly dry conditions are then expected for Friday. Below normal temperatures for late August will be in store for Friday, with highs only reaching the mid and upper 70s. && .UPDATE... Issued at 757 PM EDT Thu Aug 29 2019 Low level moisture axis preceding sfc cool front has resulted in shower and thunderstorm development across west central Lower Michigan. Latest RAP analyses indicate some weak capping persisting for surface based parcels, and this inhibition for surface based parcels will continue to creep up early this evening. Southeast sagging of low level moisture axis will allow 1000-2000 MLCAPE axis to drop into northern Indiana closer to the 03Z timeframe. Strongest upper forcing is just grazing the southern Great Lakes this evening, but with narrow zone of increasing elevated instability and lesser inhibition for elevated parcels, suspect could still see some isolated-scattered shower/storm development particularly along and north of Route 6 between 03Z and 06Z. Have noted a few reports from central Lower Michigan this evening of very large hail/wind damage, but severe threat should remain quite isolated, and even moreso as far south as local area. Still cannot rule out a very low probability of a strong storm across the far north late evening/early overnight, but confidence continues to lower. Have made some adjustments to PoPs to slow timing a bit to late evening/early overnight, but otherwise no major changes to previous forecast. && .SHORT TERM...(This Evening through Friday) Issued at 216 PM EDT Thu Aug 29 2019 An upper trough is evident on water vapor imagery sweeping across northern WI and the UP of MI. At the surface a cold front is dropping southeastwards through this same region. Low level theta-e advection is slowly moving into the far western counties this afternoon with dew points just now reaching 60 at Monticello. Mid to upper 60s dewpoints are being slowed by a cluster of storms over SE IA/NE MO. While this will not prevent additional theta-e advection, it could be delayed by a few hours. This will have implications on the ability to destabilize prior to the passage of the cold front. CAMs continue to struggle to resolve the evolution of convection over the next 8 to 12 hours, but they do seem to have a broad agreement on convection losing its strength and areal coverage as it moves across the Lake. The timing of the frontal passage has also slowed slightly which should keep the CWA primarily precip free until after 00Z. There will still be strong shear along and ahead of the front, but available instability may be less than originally anticipated. Can`t rule out a strong storm this evening, but the risk should be fairly isolated. Front pushes south of the CWA around 06Z to clear the area of rain chances. Front stalls just south of the area for Friday to provide a pleasant late summer day. Further west, a MCS is forecast develop along the stalled front over northern MO before dropping southwards. The residual MCV from this MCS could allow the front to sneak slightly northwards into the area Friday night. The result may be an isolated shower during the late night hours, but confidence is low. && .LONG TERM...(Friday Night through Thursday) Issued at 216 PM EDT Thu Aug 29 2019 The stalled front returns slowly northwards Saturday through Sunday night. During that timeframe a series of perturbations are expected to progress east within broad height falls over the area. This will result in off and on rain chances throughout the weekend. Dry conditions are expected for the start of next week as a ridge builds over the Plains. A brief window for rain exits around mid-week as a fast moving closed low moves across the northern Great Lakes. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) Issued at 753 PM EDT Thu Aug 29 2019 Low level moisture axis across the western Great Lakes will sag southeast in advance of a cool front. This moisture axis should provide a narrow zone of elevated instability that could support a potential of isolated/scattered showers/storms across extreme northern Indiana/southern Lower Michigan in the 03Z-06Z timeframe. Forcing is somewhat limited however, with stronger upper short wave working across the northern Great Lakes. With low confidence in any showers affecting terminals, will maintain VCSH mention at KSBN through the early overnight. Gusty southwest winds to 25 to 30 knots to begin the period will rapidly diminish with boundary layer decoupling into the 10 to 15 knot range after 01Z. VFR conditions are expected to persist this period, with dry conditions Friday and a potential of some sct-bkn mid level cloudiness. Did maintain LLWS mention at KFWA this evening/early overnight, but conditions should improve in this respect after 06Z. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...Beach Hazards Statement until 2 AM EDT Friday for MIZ077. OH...NONE. LM...Small Craft Advisory until 2 AM EDT Friday for LMZ043. Small Craft Advisory until 11 PM EDT this evening for LMZ046. && $$ UPDATE...Marsili SYNOPSIS...Marsili SHORT TERM...CM LONG TERM...CM AVIATION...Marsili Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Key West FL
1124 PM EDT Thu Aug 29 2019 .SHORT TERM... What kind of weather will the Florida Keys have during preparations for Hurricane Dorian? The next few days will be characterized by above normal chances of showers and thunderstorms here at a time that is normally the peak of the wet season. A broad inverted surface trough (separate and not directly related to Dorian) has been slowly moving west across the Keys this evening. This feature seems to have enhanced our shower and thunderstorm activity today. Through Saturday, the trough will continue to move west and reach the Central Gulf. In its wake, southeast flow will develop, deepen, and strengthen a bit through early Saturday. The air mass will continue to be richly moist, with Precipitable Water values of 2" or more. The experimental 00z Caribbean HRRR model shows abundant shower and thunderstorm development late tonight and Friday morning near the Keys and upwind to the southeast. Recent days have already featured a plethora of shower and thunderstorm activity, and this will continue to be the case through Saturday. In fact, coverage may even pick up a little by Saturday as the moderate and somewhat deep southeast winds across the area increase moisture flux and transport. A narrow ridge will pass across the Keys around Saturday night or early Sunday. This ridge is simply a de facto dead zone between the trough exiting to our west and the western edge of Dorian`s circulation to our east. This could come with a period of drier weather, but lack of confidence in timing leads to a broad-brushed 50 percent chance of rain throughout the preparation period for Dorian. This is an above normal chance of rain for this time of year. && .MARINE... A broad inverted trough axis is currently located near or just west of Key West. It will continue to move west to the Central Gulf by Saturday. This will bring a gradual turn of our winds out of the southeast overnight, with speeds increasing on Friday and Friday night. By early Saturday morning, mainly moderate and possibly fresh southeast breezes will prevail. Winds will then ease over the course of Saturday and Saturday night, with a weak de facto ridge separating the trough and Hurricane Dorian`s circulation passes across the Keys. Then the future track, size, strength and timing of Hurricane Dorian will drive the marine forecast from Sunday through early next week. Relative to the Keys waters, the official NHC forecast still moves Dorian north of the area during the first half of next week. This means we should experience westerly winds as Dorian makes its closest approach to the Keys. Of course, wind speeds will depend on how close Dorian tracks to the Keys, but our more northern and eastern waters have the highest probabilities for experiencing higher winds, and sooner than our more southern and western waters. Wind speed probabilities from NHC have triggered Tropical Expressions of Uncertainty wording in the Coastal Waters Forecast, i.e. wording such as Tropical Storm Conditions Possible or Hurricane Conditions Possible, for various marine zones at various times from Sunday through Monday night. && .AVIATION... Overnight and early Friday, although VFR cigs and VIS will prevail at both the KEYW and KMTH island terminals, a trough will allow for widely scattered to scattered showers and thunderstorms to impact either/both terminals at times. Have included VCTS for KEYW after 06Z to 12Z given the threat of new boundaries upstream, with VCSH at MTH. Surface winds will be variable at 6 kts or less, except may be gusty in and near showers, storms and boundaries that impact the terminals. VFR conditions will prevail at both the terminals. && .TROPICAL... At 11 pm, the center of Hurricane Dorian was located near latitude 23.3N, longitude 68.4W, or approximately 760 miles east to east-southeast of Ocean Reef. By the time Dorian reaches the east coast of Florida during the first half of next week, it is forecast to be a major hurricane. The 11 pm NHC advisory shifted the forecast track about 30 miles south with its eventual landfall point along the east-central or southeast coast of Florida. More importantly for the Keys, the forecast cone now encompasses the entire island chain, indicating it is within the range of potential tracks. Of course, impacts extend well out and away from the track. Given the range of possibilities and recent forecast trends, all of the Florida Keys are on the hook in needing to prepare and be ready for Hurricane Dorian. NHC currently forecasts the earliest most reasonable arrival time of tropical force winds to be Sunday morning and Sunday afternoon over the Upper Keys and Lower Keys respectively, with the most likely onset time about 18 hours later. The importance of the earliest arrival time is this: it is the time by which you should have preparations complete. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Haner Aviation/Nowcasts....Futterman Data Collection......DR Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service North Platte NE
655 PM CDT Thu Aug 29 2019 .SHORT TERM...(This evening through Friday night) Issued at 322 PM CDT Thu Aug 29 2019 An upper level disturbance across nrn Colorado moves through swrn Nebraska this evening. The rapid refresh models are generally keeping thunderstorm development across KS and scntl Nebraska while the NAMnest and model blend develop storms farther north and west along and south of Interstate 80. The southward trend in the RR models is the result of a strong h700mb cap holding down high instability and the progress of a sfc cold front dropping into swrn Nebraska. MLCAPE is projected to be around 4000 J/KG early this evening and winds aloft at 500mb are forecast to be around 30kts. This would certainly be sufficient for severe thunderstorms and the forecast this evening uses a blend of RR and other models for a chance of storms mostly south of the Interstate. Another rain chance develops Friday and Friday night as a result of a disturbance across WA/OR dropping through Nebraska. The moisture, at least aloft, is very good with h700mb-h300mb RH around 70 percent, but the lower levels are very dry. The forecast is for a chance of showers and POPs are capped at 50 percent as a result of the dry air at the lower levels. Thunderstorms are in place across the Panhandle and south of Interstate 80. The temperature forecast tonight, Friday and Friday night uses the guidance blend plus bias correction. This forecast is warmer than the straight guidance blend. Temperatures Friday could be on the warm side of the forecast envelop if the rain does not materialize. .LONG TERM...(Saturday through Thursday) Issued at 322 PM CDT Thu Aug 29 2019 The upper level ridge of high pressure which has governed temperatures across the wrn U.S. this summer migrates north Monday and then retreats back south Tuesday and beyond. A dry forecast is in place after Saturday morning. The model blend produces highs in the upper 80s across wrn and ncntl Nebraska Monday. H700mb temperatures in the mid teens Celsius and h850mb temperatures above 30C would support highs 5F to 10F warmer but the heating cycle is weak in September. A fairly strong cold front moves through Tuesday cooling highs back down to the 70s to around 80. Rain chances develops Tuesday night and Wednesday night but mostly isolated POPs are in place. The moisture looks pretty good as a slug of subtropical moisture will lift through the Rockies and the forcing is a strong disturbance moving through the Dakotas. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 650 PM CDT Thu Aug 29 2019 Scattered TSTMS will end this evening with skies generally partly cloudy overnight. Ceilings will remain above MVFR and VFR will be the rule overnight. Ceilings will lower across portions of central into southwest Nebraska Friday morning with MVFR conditions expected. MVFR will then persist into the afternoon hours. VFR should rule across northern Nebraska through the day. Winds will be from the northeast tonight becoming east to southeast Friday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Taylor
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday) Issued at 321 PM CDT Thu Aug 29 2019 Water vapor satellite early this afternoon showed an upper level trough moving southeast across eastern WY into northeast CO. A more amplified upper level trough was shifting east across the upper Midwest into the western Great Lakes States. At the surface a cold front extended from central WI, southwest into south central NE, then extended west-northwest into southwest NE. Southerly surface and 850mb winds were advecting richer gulf moisture northward across the CWA. Dewpoints were in the mid 70s this afternoon across the CWA. There may be enough surface convergence for thunderstorms to develop along the surface front in southern NE along the KS border late this afternoon. Therefore, I added a slight chance for thunderstorms across the far northern counties late this afternoon. MLCAPE values at 19Z were in the 3,000 to 4000 J/KG range, and effective 0-6 KM shear was increasing to around 30 KTS along the border. Therefore the environment will be favorable for a few sever thunderstorms across southern NE, which may skim across the norther counties along the NE border late this afternoon. Tonight, the southern stream H5 trough across southern WY/northeast CO will dig southeast across eastern KS during the early morning hours of Friday. Low-level CAA across the upper Midwest will allow the surface front to push southward into the CWA this evening. The combination of DCVA ahead of the approaching H5 trough and surface convergence ahead of the front will allow widespread thunderstorms to develop across northeast KS and extending west- northwest along the front into north central KS/south central NE. Several CAM models show a couple complexes of thunderstorms developing across north central and northeast KS during the mid evening hours along the front, which may develop into an forward propagating QLCS that will track southeast across the CWA during the late evening and early morning hours of Friday. The environment will be favorable, given a increasing southwesterly low-level jet, MLCAPE/MUCAPE of around 3000-40000 J/KG and 0-6 KM shear increasing to 30 KTS as the southern stream H5 trough approaches from the northwest. The primary hazards from a developing QLCS will be damaging wind gusts and heavy rainfall. The ERSL HRRR model actually shows more convective clusters, similar to HP supercells developing along the front by 3Z and moving southeast across the CWA. If we get rotating updrafts embedded within the line then there could be isolated large hail. I cannot totally rule out short lived meso vortices within the QLCS, which could produce a few weak isolated tornadoes. Most numerical models move the severe thunderstorms clusters/QLCS southeast of the CWA after 9Z. We may see showers and a few elevated thunderstorms continuing past 12Z to the northwest of the OFB/front through the mid morning hours of Friday. Even though the QLCS will be fast moving it could produce 1 to 2 inch rainfall rates per hours and in a few hours there may be 1 to 3 inches of rainfall. This may lead to flash flooding as the line move southeast across the CWA. Therefore, I have issued a flash flood watch from 3Z FRI through 18Z FRI. I kept the northern terr of counties out of the watch since the thunderstorms may be more scattered before evolving into a line/QLCS. Friday afternoon, the front will stall out across southeast KS and extend west into southwest KS. Expect mostly cloudy skies through the afternoon. It will probably remain dry through the afternoon hours. Highs will be cooler north of the front, with mid 70s to around 80 across the CWA. .LONG TERM...(Friday night through Thursday) Issued at 321 PM CDT Thu Aug 29 2019 Friday night through Saturday, another perturbation embedded within the northwest flow aloft will move southeast across the Plains. The LLJ will transport richer moisture northward across the front and elevated thunderstorms will develop Friday evening and through the night. At this time the better chance for severe thunderstorms will remain across southern KS and northern OK. The heavier rainfall should shift southeast of the CWA during the mid morning hours of Saturday, as surface high pressure builds southwest across the CWA. Saturday night through Sunday, another minor perturbation will move southeast across the Plains and may cause a chance for showers and thunderstorms Saturday night into early Sunday morning. A broad upper level ridge across the southwestern US will build east into the southern Plains Sunday afternoon. Monday through Tuesday, high temperatures may increase towards 90 degrees as the upper ridge builds east across the southern Plains. Expect dry conditions. Wednesday through Thursday, an upper level trough will amplify across the Great Lakes States and cause a weak front to push southwest across the CWA. Since the upper ridge will be across KS, I don`t think we`ll see much in the way of upper level support for thunderstorms as the surface front pushes southwest across the CWA early Wednesday morning. High will cool back into the upper 70s to mid 80s. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 639 PM CDT Thu Aug 29 2019 VFR prevails with focus being on a line of TSRA expected to impact terminals between 02Z and 04Z. There is still some uncertainty with short term guidance on arrival times, but sided towards the slower version from the RAP/HRRR with IFR flight categories arriving in the 04Z-05Z time frame. There may also be IFR ceilings at this time, but it will largely depend upon where the heavier rain bands setup. Have ended precip by 14Z, but there is some indication from the RAP that precip could linger a bit longer into the afternoon so will need to address again at 06Z. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 10 PM CDT this evening through Friday afternoon for KSZ020>024-026-034>040-054>056-058-059. && $$ SHORT TERM...Gargan LONG TERM...Gargan AVIATION...22