Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/28/17

Area Forecast Discussion
National Weather Service Bismarck ND
937 PM CDT Sat May 27 2017 .UPDATE... Issued at 924 PM CDT Sat May 27 2017 Line of showers with gusty winds is about to push out of the far southeast portion of the forecast area in the next hour. Mesoscale models have been overdoing the precipitation associated with the wrap around moisture dropping into the forecast area from the north late this afternoon and tonight. Latest RAP looks to be catching on with a dry forecast for the remainder of the night. This is what was in our previous forecast and will continue. Did lower min temperatures just a little tonight over the southwest for Sunday morning. Should be a clear to partly cloudy night with good radiational cooling, if winds diminish enough. Appears to be a bit more of a gradient than last night so a little hesitant to drop temperatures much lower than guidance. Updated text products will be out shortly. UPDATE Issued at 628 PM CDT Sat May 27 2017 Classic inverted V sounding at Bismark this evening. Small fall- rise pressure couplet with strong subsidence behind a shortwave trough is combining with this favored environment for strong winds with convection, to produce gusty winds as high as 60 mph this afternoon across central ND. These conditions will continue through early evening from south central ND into the James River Valley. Thunderstorms have been isolated but with a slightly more unstable environment over the James River Valley, we could still see an increase in thunderstorm coverage for a few hours yet this evening before convection moves out of the area. Have updated pops/sky cover and winds based on latest satellite and radar imagery. Winds drop off pretty quickly behind the line of convection moving through the area. There is a secondary surge of higher winds pushing from Saskatchewan into northwest ND at this time but not confident this will continue to spread much farther south into the forecast area tonight as we lose daytime heating and winds decouple. Updated products will be sent shortly. && .SHORT TERM...(This evening through Sunday) Issued at 335 PM CDT Sat May 27 2017 A vigorous short wave was moving out of Southeast Saskatchewan and into the north-central North Dakota with scattered showers and isolated thunderstorms. Severe weather is not expected as low level moisture is low. That dry low level (inverted V sounding) is contributing to very gusty winds with the showers, as high as 50 mph. The subsidence behind the wave is strong and the timing would end convection by 11 PM CDT with a quickly clearing sky to just high cirrus. The wind was diurnally driven and too will quickly drop off this evening. For Sunday, similar. Diurnally driven winds increasing and under cyclonic mid level flow look for convection again in the afternoon. With no well defined mid level wave there should be more distance between the showers on Sunday and they should be more confined to the central and eastern parts of the forecast area. temperatures, in a slightly cooler airmass, about 5 degrees lower than today. .LONG TERM...(Sunday night through Saturday) Issued at 335 PM CDT Sat May 27 2017 Memorial Day looks partly sunny and cooler as the area remains under the influences of cyclonic flow, and is deeper into the cooler surface airmass. By mid week H5 ridging begins to nose in over the area with temperatures back consistently into the 70s and likely around 80 by weeks end. The ridge shows signs of breaking down for next weekend with decent chances, we will see, of showers and storms. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 924 PM CDT Sat May 27 2017 Convection with locally gusty winds has cleared the KJMS area. VFR conditions now expected through the forecast period. Northwest winds diminishing this evening then increasing once again late Sunday morning through the afternoon. Showers and thunderstorms possible Sunday afternoon at KMOT, KBIS and KJMS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...JPM LONG TERM...JPM AVIATION...TWH
Area Forecast Discussion
National Weather Service Birmingham AL
630 PM CDT Sat May 27 2017 .UPDATE... For 00Z Aviation. && .SHORT TERM... Tonight. Confidence is increasing now that showers and thunderstorms will begin to impact the area more tonight than this afternoon, so have removed the severe potential for this afternoon but added it in for tonight through the overnight hours as the next system moves into the region. Again activity will develop north and west of the area so to what extent will it hold together will determine the extent of the strong to to isolated severe storms. The HRRR has been hinting at this for several hourly runs and now the ARW is on board with the activity. Still some uncertainties with the activity as it will be outflow driven. As for the models the HRRR does have the best handle on current activity and again has for several runs now, so will adjust the forecast to closely represent the HRRR. 16 .LONG TERM... Sunday through Friday. The forecast for Sunday will largely hinge on the MCS expected to approach the area from the northwest late tonight. General consensus from the latest CAMs is that a chance of isolated to scattered showers and storms will linger for a couple hours past 12Z as an outflow boundary moves in. These would likely be in a weakened state due to the time of day and the continued presence of strong mid-level capping over the area associated with a strong EML. This outflow boundary would need to be watched for additional re-development of showers and storms later in the day, but latest guidance suggests it will retreat north of the forecast area by afternoon. This would leave the forecast area in a capped air mass with a lack of forcing to break the cap during the afternoon, as 700 mb temperatures will remain around +10-11C with dry air also present at mid-levels and the front well off to the west. For the late afternoon, will leave just a slight chances of an isolated shower/storm across the northern half of Central Alabama. If a storm develops in the afternoon, it would likely be strong to severe with hail/wind given high CAPE, steep mid-level lapse rates, and 35-45 kts of 0-6 km bulk shear. But, confidence in development is too low to include in the HWO at this time. Greater chances of showers and storms will come after sunset Sunday night, more likely some time after the 10pm-midnight timeframe. A decelerating cold front will move in from the northwest, extending southwestward from low pressure over the Great Lakes. Weak height falls will occur as the trough over the north-central US causes the Gulf ridge to be suppressed eastward, and the forecast area will begin to feel the influence of the right entrance region of a jet streak over the Ohio Valley. This upper-level forcing will result in cooling at 700 mb and allow the cap to weaken. Will keep an eye on this late Sunday night period for any strong to severe threat given the instability still present, but time of day will not be particularly favorable and bulk shear somewhat marginal. Numerous showers and thunderstorms are expected for Memorial Day in the southwest to northeast oriented moisture axis along and south of the front which will have stalled. These will be aided by weak shortwaves in the southwest flow aloft to the south of the strong upper low over the Great Lakes. Strong storms will continue to be possible, and an isolated severe storm cannot be ruled out. 0-6 km bulk shear values will be marginal at 25-35 kts, mid- level lapse rates will be weakening, and profiles will be fairly saturated. Ongoing precipitation may also hamper destabilization. Therefore, chances of an organized threat are too low to mention in the HWO at this time. The forecast area will remain in the moisture axis south of the old front Tuesday and Wednesday with continued cyclonic upper- level flow south of the upper low lifting into Ontario. Scattered showers and storms will continue across the area, with the best chances around peak heating. For the rest of the week, the upper low will continue to lift northeastward while ridging develops over the Plains. A few southern stream waves will try to under-cut the ridge. A warm and humid air mass will remain in place over Central Alabama, with continued summertime afternoon scattered showers and thunderstorms. 32/Davis && .AVIATION... 00Z TAF Discussion. A strongly capped air mass will produce rain free conditions and minimal cloud cover across central Alabama thru 06z. A line of strong to severe storms will push southward out of Tennessee and into north Alabama between 04z and 06z. The convective line will be weakening as it approaches the I-20 corridor around 08z, but it could still produce wind gusts up to 50 mph at the northern TAF sites. The storms will also contain frequent cloud to ground lightning, and gradually dissipate as they push south of I-20. MVFR cigs not associated with the convective line will likely develop across central Alabama between 06z and 08z, with the cigs holding thru at least 16z. After 16z, the cigs will likely rise above 3000 feet agl, with sct TSRA developing during the heating of the day on Sunday. 58/rose && .FIRE WEATHER... A few showers and storms will be possible across the north through Sunday, but most areas will remain warm and dry. The best rain chances hold off until Sunday night into Monday when the next upper level system and surface front approach. Critical fire weather conditions are not expected. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 68 86 69 81 65 / 40 40 60 60 40 Anniston 70 87 69 83 66 / 30 30 50 60 40 Birmingham 73 88 71 83 68 / 40 40 60 60 50 Tuscaloosa 73 89 71 84 67 / 30 30 60 70 50 Calera 72 88 71 83 67 / 20 20 60 70 50 Auburn 70 87 71 84 68 / 10 10 30 60 30 Montgomery 73 90 73 87 68 / 10 10 30 60 40 Troy 70 90 71 86 67 / 10 10 20 60 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Brownsville TX
644 PM CDT Sat May 27 2017 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...A near-repeat of conditions from the last 24 hours to the next 24 is anticipated. Current breezy SE winds will decrease to moderate this evening and overnight, then pick up again Sunday mid-morning. Wind speeds likely to be a bit lighter than today`s, though, as the pressure gradient will be relaxed somewhat as a front moves into central Texas. Main challenge is onset times of MVFR ceilings overnight at the terminals. Basically blended persistence from last night with MOS guidance products and RUC BUFKIT time-height sections. Thinking is that CIG`s will move inland from the coast, beginning shortly after sunset. Only two obs from last night recorded IFR CIG at BRO, so will not mention in this TAF set. High clouds will be in the mix throughout the next 24 hours as well (as mentioned by previous forecaster), courtesy of both a speed max at jet level and anvil cirrus from thunderstorms over the Mexican plateau. Lower cloud deck should again mix out by early afternoon Sunday. && .PREV DISCUSSION... /issued 403 PM CDT Sat May 27 2017/ ..Corrected for WPC risk of Excessive Rainfall category on Monday... SHORT TERM (Now through Sunday night ): Mid level ridging over the northwest Gulf will remain in place initially, but will shift slightly toward the northeast Gulf by Sunday night. Surface high pressure will remain in control across the Gulf waters. Ample low level moisture will remain available as moderate southeast winds continue tonight. Low temps will range from 75 to 80, and may see isolated convection fire over the Mexican mountains to the west. Winds may be just slightly weaker on Sun as the upper ridge shifts east. The heat will continue, however. High temperatures will again rage from the mid 90s to a few degrees above the century mark. Heat index values will be borderline for a heat advisory Sunday, and will therefore defer to later shifts for refinement on that point. A front will push into south Texas Sunday, but southward progress toward the CWA will be slowed as synoptic driven southeast to south winds strengthen during the day. As the front moves closer Sunday night, there may be two centers of action. The first will be upstream over the RGV Plains, where developing convection may drift south toward the northwest sector of the CWA. The second will be storms developing along the Middle Texas Coast, moving south along the coast. The models suggest that the front will still be a bit too far north Sun night to more than just marginally affect the northern tier counties of the CWA, but general thunderstorms will be possible for that area nonetheless. LONG TERM (Monday through Saturday):Models continue to trend with an unsettled, hopefully rainy, period for Deep South Texas for the coming week. A split flow pattern evolves across North America with a active subtropical jet stream developing across Northern Mexico and passing over South Texas and the Western Gulf. Atmospheric moisture deepens significantly with several shortwave trough moving along the west to east axis of the subtropical jet. This is a favorable pattern for scattered to widespread, heavy at times rainfall for Deep South Texas. Monday-Monday night: A MCS or even MCC is forecast by the global models to be ongoing or developing over Deep South Texas Monday morning with widespread thunderstorm activity through much of the day. The interaction of a cold front, an upper level disturbance and anomalous moisture (2+inches pwat) along with increasing upper level divergence should lead to a likely rain day. Model guidance, GFS/ECMWF/NAM/Canadian, all pinpointing Monday and Monday night and even Tuesday with likely to categorical rain chances. QPF amounts are totaling 2 to 5+ inches with WPC placing much of our CWA in a Marginal Risk of excessive rainfall. Flash Flood Guidance remains high with 3/6hr values ranging 3.7 to 6.9 inches, so even with no definite or widespread flooding expected at this time this bears watching due to past history of rain events this time of year with the ingredients mentioned. Atmosphere may become to "water logged" for severe weather but can not rule of isolated strong to severe storms early on in the event that may have the potential to produce hail up to one inch and gusty winds upwards to 50+ mph with sufficient instability, decent mid level lapse rates and some shear. Later Tuesday and for the rest of the week: several disturbances and sufficient moisture (pwats 1.7-2.0) should be enough to keep at least a chance of showers and thunderstorms each day. Models eyeing another significant shortwave approaching the Big Bend vicinity Thursday with increasing divergence in advance of this disturbance which might lead a bump in the pops towards the end of the week. Temperatures are not expected to be much a factor this week under this pattern with near to slightly below normal highs and near normal lows. MARINE:(Now through Sunday night): Mid level ridging and surface high pressure will dominate, producing moderate southeast to south winds and moderate seas. Obs from around the Laguna are near 20 knots, with the HRRR maintaining a few 20 knot wind barbs through the afternoon, so will let the small craft advisory on the Bay ride until its expiration at 6 pm. Winds Sunday will be a skosh less than today. A few showers or thunderstorms may develop Sun night across the northern sections of Lower Texas Coastal Waters as a front approaches from the north. Monday through Thursday...light to moderate southeast to east winds and a low to moderate sea is expected Monday and Tuesday with a weakening cold front over the Northwest Gulf waters. Pressure gradient strengthen mid to late in the week with marginal small craft advisory conditions developing by Thursday mainly for seas and possibly for wind. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 53-Schroeder/65
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
838 PM MDT Sat May 27 2017 .UPDATE... Issued at 838 PM MDT Sat May 27 2017 Mid evening update package sent which removed PoPs for the rest of tonight. Currently watching some showers that have developed along a weak shortwave moving down through the Black Hills area, with concern that we might need some PoPs across the northern Nebraska Panhandle late tonight. However NAM and HRRR both have a decent handle on the past and near term evolution of that activity, and they both dissipate it as it moves south of the Black Hills with further loss of instability. Will continue to monitor that, but for now will continue with no showers late tonight in the northeast. && .SHORT TERM...(This evening through Monday night) Issued at 237 PM MDT Sat May 27 2017 With weak instability in place, will continue to see scattered showers and isolated tstms over the next few hours, before activity decreases around 00Z with the loss of daytime heating. Cannot rule out pea sized hail with the heavier showers with the low freezing levels. The shortwave wave trough axis that is currently overhead will move southeastward into Kansas by tonight. Northwesterly flow aloft will dominate the pattern through early next week. Highs will rise around 10 degrees on Sunday, back into the 60s to low 70s for areas to the east of the Laramie Range. There will be enough aftn instability (CAPE values of 100-200 J/kg) for at least isolated to scattered showers/tstms to develop, although the activity looks less than today across the plains. A weak front will push across the region on Sunday night, with llvl winds becoming more easterly/upslope along the southern Laramie Range. All models show more storm activity in Albany/Laramie counties by Monday aftn in an area of enhanced sfc convergence. Thus, will show higher PoPs 30-40 percent for Monday. Outside of some breezy northerly winds through the remainder of the aftn, winds will be rather light in the short term period. .LONG TERM...(Tuesday through Saturday) Issued at 237 PM MDT Sat May 27 2017 Upper ridge over the western US at the start of the period will migrate very slowly eastward and be positioned roughly over the central and northern Rockies by Thursday. Temps will be gradually warming each afternoon through Thursday with Thursday likely being the warmest day. Chance for afternoon showers and thunderstorms will return by Wednesday mainly over the mountains and possibly over the plains as some mositure return gets going in S`ly to SE`ly boundary layer flow. GFS might be a little over aggressive with the amount of precip generated in this environment especially in the evening/overnight hours with only weak forcing from minor shortwaves traveling through the mean ridge and weak flow aloft. Should be a fairly robust cap in place with 700 mb temps progged at 10-12 C on the GFS and EC. Trimmed POPs back to slight chance Wednesday and Thursday over much of the area outside of the mountains. Model difference become much larger after Thursday with the EC maintaining significant ridging aloft and warm conditions through Sat with only slight chances for afternoon convection. GFS allows stronger shortwave energy to flatten the ridge with much higher chances for storms along the front range. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 631 PM MDT Sat May 27 2017 Isolated showers & t-storms persist mainly in the vcnty Laramie Range and west-central portions of Nebraska Panhandle. Expect this activity to continue through sunset before diminishing. Gusty north to northwest winds will ease with sunset as well. Sunday will see a similar pattern as today, except shower activity should hold off until after 18Z. && .FIRE WEATHER... Issued at 237 PM MDT Sat May 27 2017 No fire weather concerns through early next week. Temperatures will warm to back around normal over the next few days. However, minimum afternoon humidity values will mostly remain above 25-30 percent. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...JG SHORT TERM...ZF LONG TERM...DEL AVIATION...RJM FIRE WEATHER...ZF
Area Forecast Discussion
National Weather Service Peachtree City GA
1015 PM EDT Sat May 27 2017 .UPDATE... ...Severe Thunderstorm Watch In Effect For Portions of North GA... Always a tough call with these NW flow events and in this case...WNW flow event. First wave moved through this morning as just clouds mainly which really stabilized things longer than the models had projected. Making up for lost time now though with CAPE values pushing 2500 J/KG. There has also been an extensive cap to overcome as evidenced by impressive warming on 00Z FFC sounding. Hard to discern how far this extends into North GA and honestly not likely to matter for the first tier of counties given momentum of initial MCS. But certainly could see some weakening prior to entering the southern half of the watch but enough uncertainty there that thought it best in coordination with SPC to go another tier of counties. After that...depends more on further upstream convection and if it makes a late night run at us which would have a better chance of impacting the metro. For now have kept Atlanta area in the chance pops except northern burbs where likely will be in place. Will be a fluid situation with updates to pop grids likely to continue into the overnight period. Deese && .PREV DISCUSSION... /issued 757 PM EDT Sat May 27 2017/ PREV DISCUSSION... /issued 247 PM EDT Sat May 27 2017/ SHORT TERM /Today through Monday/... A rather complicated forecast as a series of disturbances moves across the CWA beginning tonight and through Sunday night. The MCS that was over TN early this morning has dissipated and has not put out an outflow. The hi-res models eventually caught on to this, but they still struggle with developing convection and moving it into GA. The HRRR has flip-flop several times this morning and the WRF/ARW continue to develop convection over TN and move it southeast. The problem with this is that showers that have developed over TN are moving northeast. The other issue is the strong cap over the CWA between 800 and 700 mb. Unless there is forcing, areas in north Georgia would need to rise to near 100 degrees before breaking the cap. Latest models suggest the cap doesn`t break down until Sunday morning. Have opted to go with GFS/NAM deep moisture and associated short waves to forecast the best areas for thunderstorms, which at this time both the GFS/NAM agree on extreme north Georgia tonight and Sunday with the better chances in north Georgia Sunday night. As for severe potential, if any storms develop, there is still the risk of isolated severe storms as CAPES continue to run high as well as 0 - 6km bulk shear. 17 LONG TERM /Monday Night through Friday/... A largely unsettled period can be expected through the long-term. Monday continues to exhibit the best chance for strong to severe thunderstorm activity as a front enters the area with abundant instability in place by Monday afternoon. The remainder of the extended will continue to see chances for convection each day with plentiful moisture and southwest flow aloft. Refer to the previous long-term discussion below for additional details. RW PREVIOUS LONG TERM /Issued 356 AM Sat May 27 2017/ Main forecast concern in long term period is chance for strong/severe convection on Monday. 00Z model guidance in pretty good agreement with Monday forecast. Front progged to continue to sag into the state Monday with above normal sfc temps and dewpoints. SBCAPE rises to fairly high values even for late May, GFS 2500-3500 J/kg. Deep layer shear should be sufficient for severe convection, 0-6km bulk shear mags > 30kts over much of the CWA, however low level shear quite weak with 0-1km bulk shear around 5-10kts. In such environments, we typically see severe storms with large hail and wind threats but very low risk of tornadoes. PW will be fairly high but not too abnormally high for this time of year (GFS values around 1.6 in). With large scale lift not too high, QPF also less than 1 inch in most locations Mon, so will likely see periods of heavy rain but flash flooding risk somewhat low. After front sags into middle or south GA, essentially washes out Tuesday. Moisture remains plentiful but without any forcing, any storms would be fairly isolated thru Thursday. Have kept PoPs fairly low but unlikely we will see a dry period with weak SWly flow aloft. By Thurs Night or Friday, warm advection should kick in with increase in moisture as well. Have bumped up PoPs then. SNELSON AVIATION... 00Z UPDATE... VFR conditions to start out in the short term although do expect to continue with periods of mid level cigs for the next several hours. Biggest issue will be trying to time potential TSRA episodes with guidance all over the place with possibilities. For now...into the overnight looks like the best chances but confidence so low that will only include VCSH for now. Intrusion of lower clouds from the SW overnight will require MVFR cigs aft 10Z for all sites. //ATL CONFIDENCE...00Z UPDATE... Medium on TSRA chances. High on remaining elements. Deese && .PRELIMINARY POINT TEMPS/POPS... Athens 70 89 70 87 / 30 40 30 50 Atlanta 71 87 69 84 / 30 20 20 60 Blairsville 62 84 63 79 / 70 50 60 60 Cartersville 70 86 69 83 / 60 40 50 60 Columbus 71 90 73 87 / 10 10 10 60 Gainesville 69 86 68 83 / 60 50 50 50 Macon 69 93 72 89 / 10 10 10 40 Rome 69 86 69 83 / 60 50 70 60 Peachtree City 69 88 71 85 / 20 20 20 60 Vidalia 70 93 72 92 / 5 10 10 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Deese LONG TERM....20 AVIATION...Deese
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
936 PM CDT Sat May 27 2017 .UPDATE... Several hours ago, an area of agitated cumulus/towering cu developed to the east of a bulging segment of the dryline across Montague, Clay, and Jefferson Counties. A portion of this cumulus field did manage to initiate deep moist convection across portions of Central and Southern Oklahoma, but it appears that a lingering capping inversion present on the 00Z KFWD sounding was simply too much to overcome to the south of the Red River. As a result, we`ve trimmed and then relegated low-end chance PoPs to a smaller area in the immediate vicinity of our Red River Counties through the midnight hour, but I suspect that much of the ongoing activity in Oklahoma will stay there for the time being as individual storms (and occasional splits) continue to move off towards the east- northeast. The next forecast challenge looks to arrive near or just after midnight into our forecast area. A pre-frontal wind shift is just now moving into the Oklahoma City Metro region, and extends southwestward towards Frederick at this time, with the actual cold front lagging about 50 miles behind it. The expectation at this time is for additional thunderstorms to develop along and ahead of the intruding cold front over the next several hours. As some degree of cold pool consolidation gets going and the cold front approaches, we should begin to see a more noticeable southward- push to this convective complex shortly. While forward- propagating Corfidi Vectors would tend to suggest any MCS favoring a more easterly trajectory, the presence of a significant northeast to southwest oriented theta-e plume across the region raises some eyebrows to the possibility that the southern extent may attempt to build towards the southwest--into the theta-e axis. Recent runs of the ESLR HRRRX and operational HRRR offer up some plausible scenarios given their current handling of the convective picture to our north. As a result, we`ve made very few changes to the overnight portion of the inherited forecast, which paints likely PoPs roughly north of I-20 and east of US-81, tapering gradually to slight chances to the south and west. Given the aforementioned stoutness of the capping inversion overhead, we expect overall convective vigor to gradually dwindle as activity pushes into North Texas overnight. That said, the presence of very nearly absolutely unstable lapse rates aloft and continued effective deep layer shear values of 35-45 kts means this convective complex still has the potential to deliver damaging wind gusts and large hail to portions of the region-- most notably to those areas north and east of US-81 and I-20 as rough demarcators. There may also still be a threat for a tornado or two across our far northeastern counties late tonight where a sliver of low-level instability may remain. Carlaw && .AVIATION... /ISSUED 750 PM CDT Sat May 27 2017/ /00Z TAFS/ VFR conditions prevail across the region this evening although there is some haze trapped beneath a strong capping inversion. This has allowed visibilities to drop to 4-5SM in some locations. Outside of these temporary conditions, VFR conditions will prevail with southerly winds around 15 kt. The main concern through the remainder of the night into Sunday will be convective chances and an approaching cold front with wind shift. For the remainder of the evening, the 00Z FWD sounding showed a stout capping inversion which will remain in place. The last hour of visible satellite imagery shows the once agitated cumulus field has eroded completely indicative of the strong cap. The chances for isolated thunderstorms developing in North Texas through the evening hours is very low. Later tonight, as thunderstorms become a little better organized across southern Oklahoma, we will have to watch the southward progression as a cold front moves south. We think a fairly well organized cluster of thunderstorms will head southward during the overnight hours and should be approaching the Metroplex airports by 5-6am on Sunday in a weakened state. We`ll prevail VFR through much of the overnight hours and introduce a VCTS by 5 am for all airports in the Metroplex. Confidence is still a little low on storms actually impacting the airports, but we think they will still be ongoing especially to the east. Storms should push south of the area by mid morning with northerly flow prevailing and MVFR cigs remaining in place. Cigs should improve to VFR by afternoon. At Waco, thunderstorm chances will be tied to the cold front and should at least be scattered in the vicinity of the airport by midday or shortly thereafter. Northerly flow will prevail behind the front by early afternoon with storm chances diminishing. Dunn && .PREV DISCUSSION... /ISSUED 415 PM CDT Sat May 27 2017/ The forecast today is quite complicated with regards to both heat and severe weather headlines. Fortunately, the oppressive conditions being experienced by a good portion of North and Central TX should be relegated to the remainder of this afternoon. The severe weather risk, however, looks to persist into the day on Sunday. Hot and very humid conditions will continue this afternoon and as of 3 PM, many areas near and just west of the I-35 corridor are near or just below Heat Advisory criteria. As clouds slowly thin, temperatures will continue to climb into the mid-90s. Farther south, the advisory may be a bit more on the marginal side, depending on the rate of clearing, but at this time, still expect at least a few sites on the western periphery of the advisory to experience a couple of hours with heat index values of around 105 degrees. As we`ve stressed this week, it will remain hot and very humid and people who spend prolonged periods of time outside without either adequate shade or adequate hydration (water), may experience heat exhaustion or heat stroke. Fortunately, it looks like a reprieve from the hot conditions is on tap for a good portion of the area starting tonight. Early afternoon surface analysis indicated that a sharp dryline was slowly mixing eastward from near a Lawton, OK, to Abilene, TX, line. The dryline will continue its slow trek to the east this afternoon before retreating back towards the west under quiescent conditions during the early evening hours. A cold front was noted across northwest Oklahoma and will slowly move towards the south, eventually overtaking the dryline. The dryline, but more importantly the cold front will be the main players for the severe weather threat across North and Central TX over the next 24-36 hours. For this afternoon, just about all convective allowing models are silent for much of North and Central TX this afternoon which fits the conceptual model for an environment characterized by strong capping and little in the way of synoptic scale ascent. On the smaller scale, surface winds are veered well ahead of the actual dryline along what appears to be a broad surface trough. This trough extends from near a Bowie to Decatur to Granbury line and we will have to keep an eye on this surface trough as it could provide just enough convergence to assist what should likely be buoyant surface parcels. The environment this afternoon will be characterized by extreme instability values with some forecast model soundings indicating nearly 6,000 J/kg of CAPE. While these values are quite extraordinary, it`s plausible that little to none of it will be realized compliments of a very strong capping inversion as sampled by the 12 UTC FWD sounding. If a thunderstorm can manage to develop and sustain itself, it will become severe very quickly with a high likelihood of giant hail (perhaps near 3" in diameter or greater), destructive straight line winds (70-80 MPH) and a tornado or two. While the surface wind fields aren`t necessarily overly conducive for tornadogenesis, the impressive instability values, particularly in the low levels, will more than compensate for the lack of strong low level shear. While the tornado hazard IS the most conditional risk, it will be closely monitored should storms develop as there is a potential (again, given the extreme instability) for a robust tornado or two. The atmosphere will be most prime for convective initiation after about 6-7 P.M. Some of the latest suite of hi-res guidance initiates convection across southwestern Oklahoma. This appears plausible as surface analysis revealed a nice bulge in the dryline across this region. Given the environment, some of these models do take this activity east and eventually southeastward into extreme portions of North TX. Again, this seems like a plausible solution, but given the uncertainty as to whether or not storms will even develop across OK, I`ve elected to only advertise 20-40 PoPs through the late afternoon into early evening hours. Storm chances after 00 UTC should begin to increase rapidly at this time and I do expect some sort of severe storm cluster over southern Oklahoma. Some hi-res guidance actually depicts that this complex will grow upscale rapidly and slide southeastward through our northernmost row of counties against the Red River. Should this occur, the main hazards would be large, damaging hail and destructive straight-line winds. This complex may decay as the onset of nocturnal cooling occurs. However, its cessation may be tied more to the start of the low level jet, which is forecast to become quite strong, a little later in the evening. If this complex can survive through then, it may have some additional forcing which would promote a greater longevity. A potentially second, but more probable round of thunderstorms is expected near or just after midnight as the cold front slowly slides southward. If this line of thunderstorms can remain rooted in the boundary layer and develop a strong cold pool, it has the potential to morph into a forward propagating MCS as there will be an abundance of instability as well as assistance from a 30-45 knot 925mb jet. Similar to the first round, the main hazards would be destructive straight line winds and very large hail. The most likely areas to be impacted would be locales east of I-35 and north of I-20. If two rounds of convection do develop, there could be some isolated instances of flooding or even low-end flash flooding. At this time, I do not feel compelled to go with any sort of short-fused/small areal coverage FFA given 1) the antecedent conditions across North TX do not support it as most areas missed out on the heavy rain last week and 2) the speed of both rounds of convection should be swift enough to mitigate any widespread concerns. We will keep an eye on areas along the Red River, especially across more urbanized areas where flash flooding would be more likely. All convection should be efficient at producing brief bursts of heavy rain, however, given the high amount of moisture in place. Close to sunrise, there`s a great deal of uncertainty as to how quickly this potential line of convection decays. Some guidance suggests that this complex will plow through just about the entire eastern half of the forecast area, while some guidance indicates a quick and painless death of the MCS as it nears I-20. For now, will confine PoPs to far eastern zones with slightly lower PoPs elsewhere. The cold front will continue to slowly trudge southward with breezy northerly winds in its wake. This feature looks to be quite slow given that there isn`t a ton of strong cold advection southward. The slow progression of the front means that it`ll likely not clear our far southern and southeastern counties by Sunday night. While it`s likely to be mostly cloudy through the day, surface moisture will be quite high. The mid-level flow isn`t overly impressive, but steep lapse rates aloft coupled with modest shear values may support multicell storm clusters capable of some damaging downburst winds and potentially large hail. There will be a heavy rain threat as well, again, given the high moisture content in the atmosphere. If the front slides to the south a little quicker than currently anticipated, it`s quite possible that the severe weather threat also shifts to the south. For now, we will have to simply monitor the front`s motion through the overnight hours to get a better handle on this. For Memorial Day, it appears that areas generally along and north of I-20 will be mostly dry. Unfortunately, areas farther to the south will be at greatest risk for showers and thunderstorms. At this time, the severe weather risk is a little unclear, but forecast soundings do not generally support widespread severe storms on Memorial Day, but we will keep an eye on this, given the multitude of outdoor activities. For next week, the threat for showers and thunderstorms will continue as low level moisture lingers across the area. Unfortunately, there still does not appear to be any meaningful signs of strong ascent for most days. As a result, PoPs were broad-brushed just about each day. Towards the end of next week, it appears that a slow moving upper low may be more of a focus for a more concentrated area of showers and thunderstorms. 24-Bain && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 75 85 65 86 66 / 40 40 20 10 5 Waco 76 87 65 83 66 / 10 50 50 40 20 Paris 71 82 62 84 62 / 80 50 10 10 5 Denton 72 84 60 86 61 / 50 40 10 10 5 McKinney 74 83 62 85 62 / 60 50 10 10 5 Dallas 76 85 66 87 67 / 40 40 20 10 5 Terrell 74 83 66 85 64 / 50 50 30 20 10 Corsicana 74 85 67 83 67 / 30 40 50 40 20 Temple 75 88 66 82 68 / 10 50 60 40 30 Mineral Wells 72 84 62 87 60 / 30 20 10 10 5 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Goodland KS
709 PM MDT Sat May 27 2017 .UPDATE... Issued at 703 PM MDT Sat May 27 2017 Made adjustment to timing of PoPs, decrease in coverage of thunder mention, and removed severe mention from HWO. Showers are trending slightly faster, and instability is significantly lowered as front remains well south of our CWA. There are some isolated showers behind the main precip area, but with decreasing mid level lapse rates this activity should diminish after sunset. Timing of main area of precip associated with shortwave should be out of our CWA by midnight. UPDATE Issued at 254 PM MDT Sat May 27 2017 Am becoming increasingly doubtful of severe weather developing over the southwest portion of the Tri-State Area this afternoon. Wave clouds on visible satellite continue to be prevalent, while the cumulus field continues to remain further south by the front. Can`t completely rule out the possibility of severe weather along the far southern edge over the forecast area, but am not very confident it will occur given the front should remain to the south. && .SHORT TERM...(This evening through Sunday) Issued at 115 PM MDT Sat May 27 2017 Latest upper air analysis shows a trough axis over the Northern Plains extending southwest to the Central Rockies. Satellite imagery shows a defined line of clouds accompanying the trough axis east with colder cloud tops at the base of the trough. Ahead of the trough axis wave clouds indicated a stable environment. Latest radar imagery showed a line of showers accompanying the trough axis east. On the south end of the line a cluster of storms had developed at the base of the trough axis. At the surface the cold front was near the KS/OK border arcing northwest to near Denver. Am expecting this cluster to be the focus for attention this afternoon for the potential of strong to severe storms as the cluster moves southeast. The better chance for severe weather will be south of Cheyenne and Greeley/Wichita counties near the front where the higher instability will be. Main hazard with this cluster will be large hail up to ping-pong ball size if severe storms develop. Have limited optimism due to CAPE of 1000j/kg or less. However effective deep layer shear is 55kts by early evening, so if an updraft can avoid being sheared apart large hail will be very likely. DCAPE values and HRRR ensemble model runs both show a low probability of severe wind gusts. Tonight the threat for severe weather will be southeast of the forecast area, if any is still ongoing. There may be some lingering storm activity ahead of the approaching trough axis. Cloud cover will exit ahead of the trough axis. Behind the trough axis a surface high will move through. Sunday will be warmer as northwest winds bring in WAA. Winds will be light as a 850mb ridge moves through. A clear sky is expected due to dry northwest flow overhead. .LONG TERM...(Sunday night through Saturday) Issued at 115 PM MDT Sat May 27 2017 Sunday night: Upper level ridge will build aloft bringing drier conditions to the area. Temperatures will be near to slightly below normal. Monday-Tuesday: Cold front moves into the area during the day Monday and becomes stalled with a northwest to southeast orientation across the CWA. Showers and a few thunderstorms will be possible Monday afternoon into Monday night for areas southwest of the front. On Tuesday, a shortwave trough pushes into the area from the northwest helping to provide extra lift and giving most of the area a chance of rain and thunderstorms. Temperatures should be close to normal. Wednesday-Thursday: Models still do not have very good agreement for this period. GFS and ECMWF have very little continuity between them. Tended to lean towards the GFS for this time frame. Area will see a chance of thunderstorms on Wednesday and Thursday afternoons. 12Z GFS soundings indicate that some of these storms could be strong or severe. Friday-Saturday: This period could remain wet and/or stormy as both the GFS and ECMWF are advertising the possibility of a negatively tilted trough or closed low approaching the CWA from the southwest. GFS solution shows high CAPE values (~2200 J/kg) but low 0-6km shear (~12 kt). One note, GFS is also showing PWAT values around 1.25 in. which could result in some heavy rain through the period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 529 PM MDT Sat May 27 2017 VFR conditions should continue at KGLD and KMCK through the TAF period. Gusty winds and showers end this evening, with winds remaining below 12kt until sunrise Sunday. I couldn`t rule out of a thunderstorm this evening at KGLD, but current radar trends lower confidence and showers were favored in TAFs. KMCK has less of a chance for showers, but a few could move within the vicinity of the terminal early in the TAF period. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...JTL LONG TERM...SME AVIATION...DR
Area Forecast Discussion
National Weather Service Huntsville AL
807 PM CDT Sat May 27 2017 .NEAR TERM...(Tonight) Issued at 807 PM CDT Sat May 27 2017 Updated mainly concerning development and evolution of convection to our north. This convection was basically along the I-40 corridor from Jackson to south of Nashville to west of Cookeville. Even with somewhat cooler conditions nearing dusk, very unstable conditions continued with mixed layer and surface CAPE values in the 2000-3000 J/kg range. Also noticed lower level shear values increasing to our north as the convection nears. The HRRR continues a trend of bringing the showers across the area in the 04-05Z timeframe. But looking at the current radar and storm movement, think they will be here an hour or so earlier. Strong to damaging wind gusts and large hail are the main threats. Higher shear values keeps the possibility of a brief tornado in the picture too. At this time, think the convection will affect mainly our southern middle Tennessee and far northeast Alabama counties first, then the remainder of the area in a NNW-SSE manner in the late evening and overnight. Update wise, sped up arrival of likely rain chances for our northern areas a few hours earlier. Left temperatures and the remaining parameters as is for now. .SHORT TERM...(Sunday through Monday) Issued at 250 PM CDT Sat May 27 2017 If the MCS does move through tonight much of the hires guidance has it through the area shortly after sunrise Sunday. However, the cold front will still be lingering off the NW and should spark another round of convection that will drop S/SE through the area Sunday afternoon/night. Timing again is very uncertain with the MCS potentially limiting activity as we may be too worked over. Plus, the main synoptic forcing with the front will be off to the NE. CAPE and shear parameters are a bit lower on Sunday and the mid-level dry air we have over the area today will be gone. So, the potential for the stronger damaging winds may not be as great. But hail and some stronger wind gusts are still possible with storms along the front. The forecast uses more of a blend because of the lingering uncertainty but if we don`t have the MCS come through we could end up with some severe storms on Sunday with the front. With the front losing it`s main forcing it begins to slow down as it moves through the area Sunday into Monday. This could shift the threat from severe to more of a heavy rain and flooding threat on Monday. Did stick to a blend of guidance for PoPs on Monday and kept 50 to 60 PoPs for much of the area during the day. Thunderstorm chances begin to decrease as we lose heating Monday evening. With the increased rain chances and cloud cover temps will be a little "cooler" on Monday compared to today and Sunday. Hoping to see some more consistency in the guidance in the next few runs. .LONG TERM...(Monday night through Friday) Issued at 250 PM CDT Sat May 27 2017 A broad upper trough remains over N. MN at 00z Monday with a cold front that will essentially be stalled across N. AL. The upper low remains wedged between strong high pressure over the N. Atlantic and the N. Pacific with all the energy well to our north. Locally, a mid level ridge anchored off the SE coast will allow short waves to ride along it SW to NE across N. AL. Continued SW flow at the surface will keep ushering moisture into the area as well. The upper low finally opens up and meanders eastward on Friday. At the same time, a weak upper low develops over the midwest and will track eastward. What this all means is that isolated to scattered thunderstorms will essentially stay in the forecast for the entire long term period, Monday night through Saturday night. The highest coverages will be in the afternoon but isolated showers/storms will probably linger each evening. Shear is non existent most of the week so would expected convectively induced showers and maybe a strong storm possible each afternoon. The dynamics for the weekend look stronger with greater instability so we`ll watch that more in coming forecasts. Temperatures for the week will be near normal with highs in the lower 80s and lows in the lower to mid 60s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 632 PM CDT Sat May 27 2017 Unsettled weather this TAF, as a series of convective systems move NW to SE across the region. Even in the short term, there is low confidence regarding timing of these systems. One of the models is forecasting thunderstorm complexes now across the KY/TN border and SE MO should move across this area in the late evening. Other output has those systems impacting the region during the overnight. Stayed with the quicker solution this issuance. Given an unstable atmosphere across the region, strong erratic wind gusts are expected as storm complex traverses the region. Have lowered VIS/CIG values into the lower MVFR range, with IFR or lower values possible. MVFR CIGs should continue to after sunrise Sunday, with scattered convection into the early morning. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...Stumpf LONG TERM...LN AVIATION...RSB For more information please visit our website at
Area Forecast Discussion
National Weather Service Lincoln IL
933 PM CDT Sat May 27 2017 .UPDATE... Issued at 932 PM CDT Sat May 27 2017 With several convective systems off to the south of central IL in southern MO through southern IL, KY, and TN, subsidence in central IL has inhibited any convection so far. Although enough instability overnight will continue that storms can`t be entirely ruled out, looks like any significant chances will hold off until morning when a shortwave arrives from the west. For tonight, any significant chance for rain/thundestorms is from around I-70 southward. Severe thunderstorm outlook has been diminished to just a marginal risk for tonight. Have sent updates for the above mentioned featured. && .SHORT TERM...(This evening through Sunday) ISSUED AT 328 PM CDT Sat May 27 2017 20z/3pm surface analysis shows stationary frontal boundary extending from southeast Kansas eastward into the Ohio River Valley. Dewpoints south of the front are currently in the lower to middle 70s, creating a highly unstable environment characterized by CAPE values of 3000-4000J/kg along/south of the I-64 corridor. Meanwhile north of the front, a much more stable airmass is in place across much of central Illinois where lower to middle 60s dewpoints are yielding CAPEs of only 1000-1500J/kg. Latest radar mosaic is showing several clusters of thunderstorms developing along/south of the front, with the most organized linear structure over central/southern Missouri. This feature will race eastward along the boundary, largely remaining south of the KILX CWA this evening. Based on radar timing tools, the northern fringe of this system will brush the I-70 corridor between 00z and 04z...with the main widespread damaging wind threat focusing further south across southern Illinois and western Kentucky. HRRR appears to have a good handle on the current situation and shows this scenario unfolding over the next several hours. As a result, have updated PoPs to go with likely along/south of a Robinson line this evening. Will need to closely monitor areas from Effingham and Robinson southward, as the potential still exists for damaging wind gusts and hail this evening. Further north, will only carry slight to chance PoPs for showers/thunder elsewhere around central Illinois. The main line of storms will quickly pass into southern Indiana/Kentucky by around midnight, with only isolated showers expected overnight. Low pressure will track across central Illinois on Sunday, keeping rain chances alive throughout the day. Instability/shear parameters are meager across the area, with the greatest instability developing further southeast across the Ohio River Valley. As a result, the latest Day 2 Convective Outlook from SPC has shifted the slight risk out of the SE CWA. Will carry chance PoPs throughout the day, with rain chances quickly coming to an end from west to east by late afternoon and early evening. .LONG TERM...(Sunday night through Saturday) ISSUED AT 328 PM CDT Sat May 27 2017 Pronounced upper low will dig southward through Ontario into the Great Lakes early next week, resulting in a cooling trend across central Illinois. A weak surface trough will sink southward around the parent low on Monday, potentially bringing a few showers. Convergence along the boundary will be weak and with the main upper cold core still to the north, think areal coverage of precip will remain low. As a result, have only mentioned slight chance PoPs for showers/thunder along and north of I-74 Monday afternoon. Cool/dry conditions will prevail Monday night into Tuesday before the next potential system spreads showers across south-central Illinois Tuesday night. After that, mainly dry weather is expected until a stronger system brings the next significant chance for rain by Friday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 648 PM CDT Sat May 27 2017 Two areas of thunderstorms this evening appear they will likely pass by the central IL terminals to the north and south, respectively, with minimal impacts in central IL. At this time, no mention of thunderstorms is warranted by current trends for this evening, however overnight there will be slight chances of thunderstorms too low for mention at this time, and a disturbance late Sunday morning will bring another chance of thunderstorms. High- res models are suggesting low clouds/fog will develop late tonight once the convection ends, so have MVFR cigs/vsby after 10z until late morning to early afternoon Sunday, IFR at KPIA where guidance values are lower. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...Barnes LONG TERM...Barnes AVIATION...37
National Weather Service Jackson KY
1032 PM EDT Sat May 27 2017 .UPDATE... Issued at 1032 PM EDT SAT MAY 27 2017 The watch was allowed to expire on time, as the stronger convection has made its way further southeast into Tennessee. Moderate stratiform rainfall, with embedded thunder, will gradually diminish across the southwest half of the area over the next 1 to 2 hours. Some convection has fired up across north central Kentucky, but this will likely die out before making it much further east. Included areas of dense fog in the valleys, with the thicker cirrus shield likely thinning out with time. Updates have been sent. UPDATE Issued at 921 PM EDT SAT MAY 27 2017 Storms are gradually weakening across the area, with mainly a heavy rainfall/flash flooding threat to continue across portions of the Cumberland Valley over the next few hours. Will likely be dropping the watch on time. The latest HRRR and radar mosaic trends suggest a quieter overnight, and given the lack of forcing and the already worked over atmosphere, this seems reasonable. Have trended down with the POPs into Sunday morning, before a possible re-fire occurs tomorrow afternoon, although forcing still may be on the weaker side. Will have to take a look at fog for the overnight as well, with only weak southerly flow remaining in place at the low levels and thicker debris clouds gradually thinning out with time. Updates have been sent. && .SHORT TERM...(This evening through Sunday night) Issued at 429 PM EDT SAT MAY 27 2017 The latest surface map features a stalled frontal boundary aligned from near the Ohio River back towards Oklahoma. Aloft, a positively tilted trough, stemming from an upper level low spiraling across Manitoba, is positioned from the northern Plains down across the Four Corners region. A few short wave troughs are traversing the more zonal flow in place along and east of the Mississippi River. Convection has fired up along the frontal zone to our north, as well along some leftover outflow across central Kentucky. A short wave trough is also moving through the eastern half of TN/KY, helping to weaken the cap, that had held back convection through the morning hours. Deeper and more organized convection has also fired up back towards southern Missouri, where very prominent instability exists. The models have been very erratic with convective initiation and the evolution of it over the next 24 hours. As such, the forecast is lower confidence through Sunday. Through this evening...scattered to numerous showers and thunderstorms will continue to develop and move off to the east and northeast. A few of these have already reached severe limits, along with locally heavy rainfall with some cells training in places. An overall diminishment is expected after 01 or 02z. Later tonight, the higher resolution short term model guidance suggests less of a widespread wind damage threat across eastern Kentucky, as most of the CAMs are taking organized convection well to our southwest. This seems reasonable based on the good Theta-E gradient set up across southeast MO and western KY/TN, where the better instability bubble exists. There may still be some outflow generated convection into our area on the eastern flank of this complex, so have broad-brushed a 50 POP across the area. Most of the CAMS suggest very little redevelopment into Sunday afternoon in the wake of the complex; however, if we do not see much affect from the outflow, then the atmosphere may recharge for the afternoon. The one issue will be forcing, as upper level heights look mainly neutral, and the surface front will still be located to our northwest. As such, have only included chance POPs for the afternoon, but instability will be ample once again, so anything that does go could approach severe limits. The front will approach from the northwest Sunday night, bringing another round of showers and thunderstorms. The severe potential will likely be diminishing with the loss of instability, but heavy rain will still be a concern. .LONG TERM...(Monday through Saturday) Issued at 345 PM EDT SAT MAY 27 2017 Precipitation will be exiting during the day Monday as a shortwave moves east of the region along with a surface cold front, allowing drier air to usher in behind. A secondary cold front is projected to develop just west of our CWA during the day Tuesday, remaining nearly stationary over the next 24 hours. A longwave trough axis will also begin move through the state during this time. As such, models are not in good agreement with the mesoscale features, specifically the location and timing of precip developing with this system. Went ahead and kept isolated POPs in for Tuesday afternoon as daytime heating should help kick off some convection ahead of this frontal feature. Pops will then increase across the SE into the day Wednesday as the front finally starts shifting eastward across the state. Did leave out thunder late Tuesday night as latest GFS20 forecast soundings were showing a hefty llvl inversion in place that will inhibit instability. Showers and thunderstorms that develop during the day Wednesday will taper off through the evening as the frontal boundary passes through and a drier airmass moves in once more. High pressure and dry weather will remain in place through Thursday. By Thursday night/Friday, a stationary boundary will likely set up just south of the state, interacting with a potential upper level shortwave that will move through the region during this time. Although models are overall not in very good agreement about the timing and placement of the mesoscale features, they do generally agree that this will bring the return of shower and thunderstorm chances to the state Thursday night into Friday, lingering through the end of the forecast period Saturday as the boundary to our south remains in place. Unfortunately the GFS and ECMWF are actually not in good agreement about this feature during this time, though both do produce the above mentioned precip, so stuck close to the blend for this time period. Overall there are only minor variations in the afternoon temps during the extended portion of the forecast, with high temps expected to range from the mid/upper 70s to near 80. Overnight lows will generally be in the 50s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 921 PM EDT SAT MAY 27 2017 Thunderstorms will gradually wind down across a line from KSME to KI35. IFR or worse conditions will improve to VFR. Fog may be a factor between 06 and 12z, but light south winds may stay up just enough in the broader valleys to prevent it from becoming too widespread. Scattered convection will threaten once again Sunday afternoon and will include VCTS. Winds will remain out of south and southwest at around 5 kts. && .JKL WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through late Sunday night for KYZ050>052- 058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...GEOGERIAN SHORT TERM...GEOGERIAN LONG TERM...JMW AVIATION...GEOGERIAN
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
810 PM CDT Sat May 27 2017 .UPDATE... 810 PM CDT Changes to the forecast for the rest of tonight into Sunday morning have been minor with just a tad higher chance for some showers and possibly storms mentioned across north central Illinois, with probably the best chance still looking to be very late tonight/Sunday morning. Across far eastern Iowa early this evening there is a short wave impulse that was seen on earlier satellite imagery before high clouds shrouded the area. Some light rain with isolated convection has spread into southern Wisconsin, with one shower across Boone County. A few showers could continue to spring up on the eastern/southern trajectory of this short wave, so across mainly north central Illinois and the IL/WI border region of northeast Illinois. The 00Z DVN sounding indicated around 800 J/kg of MUCAPE, and enough effective shear that if a storm were to pop across north central Illinois it could have some organization to briefly be strong. All in all though, a pretty quiet weather evening. A few showers, possibly a storm or two, could fester in these same areas into overnight. In addition, it continues to look like elevated return flow and instability also creep into the southern CWA late tonight in response to cyclogenesis across western/southwestern Illinois. So could also see a few storms pop up in that area. Overall this was well covered by the forecast. With some of the better upper level forcing ahead of the primary trough moving over the area early Sunday, would expect then to see an uptick in shower coverage. While a decent spread in 18Z guidance on the rate of speed of the front Sunday afternoon, it still looks like by peak afternoon heating it should be east of the area, keeping the main potential for any severe storms east. MTF && .SHORT TERM... 222 PM CDT Through Sunday... Light winds and mostly sunny skies will continue into this evening, except for lingering cloud cover east of I-55. The two big factors in the forecast are the convective complexes over Iowa and Missouri. Models have struggled to capture convection today, but the latest run of the RAP and HRRR seem to have a better handle on the situation. The latest RAP analysis features minimal CAPE values and lingering CIN across the region. Ample sunshine will certainly help erode CIN, but dewpoint depressions are mostly 10 degrees or more. Therefore, expecting the storm complex over Iowa to dissipate before it reaches north central IL. Lightning strikes are rapidly decreasing in the complex, which supports the idea that the system is weakening. In addition, a new and much more impressive convective complex is taking shape over Missouri. The southern convection should rob us of CAPE and moisture. Overall have high confidence in a dry and really nice afternoon, but confidence lowers to medium-high for overnight. Thinking the storms over Iowa will continue northeast to Wisconsin this evening. Areas northwest of a McHenry to DeKalb to Peru line may see showers this evening, but only have a slight chance of showers and thunderstorms in the forecast. There is a small chance that the southern storm complex clips the far southern part of the forecast area after midnight. The remainder of the night should be dry with lows around 60. Showers and storms may fester just west of the forecast area Sunday morning, and expecting showers and storms to move into the Rockford area around sunrise Sunday. Guidance differs in how quickly showers and storms will form and move through northern IL and northwest Indiana. The NAM is by far the slowest solution, and opted to go with a quicker evolution ahead of the cold front. Models suggest another band of light rain may form as the upper level vort streamer moves through. Kept a chance of showers and storms, but have low confidence in additional precip behind the first wave given very dry soundings behind the front. Kept high temps lower than climo would suggest given thick cloud cover. Highs will be in the low 70s. JEE && .LONG TERM... 222 PM CDT Sunday night through Saturday... An upper low is expected to be in place centered just north of the Great Lakes through much of the upcoming week resulting in active weather and below normal temperatures. A blocky weather pattern will be in place over North America much of the upcoming week as a strong ridge remains anchored over the central and western half of the country while an upper low meanders over the Canadian Prairies and northern Great Lakes region with pin wheeling vort lobes rotating across the local area. First, and one of the stronger in a series of waves, will drop across the region on Monday with a modest surface reflection/cold front moving across northern Illinois and northwest Indiana primarily during the afternoon. Overall forcing is not impressive with only modest low level convergence noted along the front and a narrow corridor of DCVA associated with the shortwave, but steep low to mid level lapse rates will be in place with no CIN noted on GFS forecast soundings which should allow for some scattered showers and possibly a thunderstorm or two to develop. Slight chances for precip continue Tuesday as lower amplitude shortwaves continue to rotate through the region. Steep low level lapse rates persist and weak diurnal instability is expected to develop. Showers will be a possibility especially if shortwave timing falls within peak heating. The GFS strengthens a mid level capping inversion Wednesday as the upper low inches east and moderately strong mid level height rises build into the Upper Midwest resulting in subsidence aloft which should keep the area dry midweek. This will continue on Thursday as the surface high moves overhead. Expect a warming trend to occur late in the week into next weekend as the upper low slowly departs east, but with warmer temperatures will also come additional chances for showers and thunderstorms. Deubelbeiss && .AVIATION... For the 00Z TAFs... 642 pm...Main forecast concern is potential for thunderstorms Sunday morning into early Sunday afternoon. Current showers and isolated thunderstorms over northeast IA are expected to continue to weaken/dissipate this evening. Some light showers or sprinkles may reach rfd in the next few hours. There remains quite a bit of uncertainty regarding precip chances late this evening and overnight. Most recent short term guidance suggests isolated/scattered activity may develop by 06z southwest of the terminals. This is a change to previous runs and confidence remains low so will maintain dry forecast overnight and monitor trends. A cold front will move across the area Sunday and scattered showers and thunderstorms are expected along/ahead of this front. Timing looks on track if they occur but also low confidence regarding coverage. A lake breeze has moved west of ord/mdw with easterly winds continuing tonight...diminishing to 5 kts or less. Many areas may become light and variable. Winds will shift northwesterly behind the cold front Sunday morning and speeds are likely to increase to 10-15 kts with some higher gusts possible...especially by mid/ late afternoon. Increasing mid clouds this evening will lower by morning and possibly into high mvfr...especially at rfd. Fairly low confidence for how prevailing mvfr cigs will become...especially after the front passes when cigs should become vfr. cms && .MARINE... 222 PM CDT Relatively light flow will continue across Lake Michigan through the remainder of the weekend as the Great Lakes fall between two areas of low pressure. A northern low will meander over Manitoba and Ontario through the weekend while a southern low will lift from the southern Great Plains to the central Great Lakes Sunday. As these lows merge over Ontario Sunday night into Monday, a fresh westerly to southwest wind will develop early next week and continue through midweek. BMD && .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...UPDATED
National Weather Service Little Rock AR
624 PM CDT Sat May 27 2017 .AVIATION... Storm system and associated precipitation will move through Arkansas over the next 24 hours. Timing for the highest precipitation and thunderstorm chances will be during the overnight hours for northern sites, in the hours either side of sunrise over the central, and around mid to late morning in the south. Conditions will be restricted to mvfr or lower near thunderstorms. Winds will change around to the southwest and west, and will be strong, variable and gusty near storms. Expect gradual improvement from north to south late in the period. TAFS already out. && .PREV DISCUSSION...(ISSUED 237 PM CDT Sat May 27 2017) DISCUSSION... Main concerns in this forecast cycle are first and second period severe storm potential. Then some lingering lighter convection on Monday, before the entire system move out of the region and lessens its impact on AR. Current convection is developing over MO this afternoon with strong to severe storms. Over AR have only seen isolated showers this afternoon with a cap indicated in the 12z KLZK sounding holding overall convection develop. Later tonight, this cap is expected to break as the upper system moves through the region, and allow plenty of convection to affect AR. Otherwise, temperatures this afternoon were mainly in the 80s, while dew point temperatures were in the 70s. More organized convection was over MO and rotating around the upper ridge. Currently the main upper lift was moving from KS to MO, while a low level jet over eastern OK to northwest AR may develop isolated convection a bit later. Timing of the upper storm system appears to be late evening in northwest AR, to midnight over more northern AR, then as the upper lift and cold front gradually sag south, additional convection will be seen over all of AR after midnight to Sunday morning. Isolated to scattered strong to severe storms are expected, with large hail, damaging winds and a tornado or two possible. Plenty of moisture, lift and instability will be present. Euro model appears to be the fastest to sag convection into north AR by midnight or a bit before, with GFS catches up with Euro overnight, while NAM is the slowest. HRRR model runs a bit inconsistent with latest more earlier convection into northern AR, while previous run a bit slower. Moderate risk over northern AR to Enhance to Slight remains over AR this afternoon, evening and tonight. SHORT TERM...Tonight Through Monday Night Convection chances will ramp up quickly in the evening over northwest to northern AR, as some lift and low level jet max moves into the area. It will take a bit long to reach more of the northern half and central AR as the upper dynamics move into AR later. All forms of severe weather are possible with the storms. The convection will last into Sunday, but severe storm threat is forecast to lower on Sunday as dynamics weaken. Rain amounts tonight to Sunday are expected from 1 to 2 inches with a few spots a bit heavier to 2.5 to 3 with precip water values now up to 1.5 inches. On Sunday, the cold front gradually sags to southern AR and focuses the convection over that region. The severe storm threat lows as the dynamics push east of AR. A lower chance of rain is held in the forecast over the south, Sunday night and through Monday, before ending as the upper flow becomes parallel to the boundary and stalls it near the AR and LA state lines. Temperatures will cool a bit behind the cold front and lows will be below normal while highs a bit to start, then warm into Tuesday. LONG TERM...Tuesday Through Saturday A large area of low pressure will be over the Great Lakes to begin the long term period with high pressure aloft over the southeast and western U.S. This pattern will continue through Tuesday then the upper ridge builds over Arkansas on Wednesday. The upper ridge weakens Friday and Saturday. The weekend cold front will be just east of the Mississippi River Monday night and high pressure will be building over Arkansas. Another front will move into north Arkansas Tuesday, become stationary, and bring small chances of showers and thunderstorms through Thursday. The front slowly moves into southern Arkansas Friday and should wobble to the north for Saturday. Rain chances will continue Friday and Saturday. Will have to see how this comes together but it could be the set up for more heavy rain...or at least prolonged rain over multiple days. Expect temperatures to run near to slightly below normal through the long term period. && .LZK Watches/Warnings/Advisories...NONE. && $$ Aviation...57
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1010 PM EDT Sat May 27 2017 .SYNOPSIS... A frontal system will drift south into the area tonight and become stationary through Sunday, then lift northeast Sunday night. A cold front will drift in Monday night and become stationary along the coast through the end of the next week. && .NEAR TERM /OVERNIGHT/... As of 1010 PM Sat...Convection moving into NE NC is currently aided by 40+ kt deep shear and 1000+ J/KG MLCAPE. The HRRR indicates a slow weakening trend with the MCS as it moves into the sound counties of the FA as instability slowly wanes. Still could see some gusty winds and heavy rain with these storms through the next 3 hrs or so. Have retained 50-60 pops far NE zones and diminished them elsewhere, as convection across wrn NC will weaken well before it reaches the coastal plain overnight. Previous discussion...As of 615 PM Sat...Convection has initiated in ctrl VA as expected early this evening. Poor man`s ensemble of the meso model suite indicates this activity advecting ESE into nrn NC through this evening and potentially impacting our nrn counties generally north of hwy 64 after 02Z (10pm). Attm WRF_ARW is performing fairly well with this convection and have blended more heavily with this model through the overnight. Have inc pops across the north to 40-60 percent with just a 20 pop far south. Most likely this convection will move into the FA as an outflow/cold pool dominated MCS as sfc based instability wanes late tonight, though ML CAPES still sufficient for some strong to potentially damaging wind gusts. Previous discussion...As of 330 PM Saturday...A few cumulus have develop over mainly inland areas late this afternoon as temperatures have risen to around 90 degrees well inland with low/mid 80s coast. Latest 3km HRRR, 4 km NAM and NSSL WRF are fairly consistent in showing line of convection associated with approaching frontal boundary and mid-level shortwave energy to arrive at around 02z- 03z over the Albemarle Sound region. The highest PoPs will be over the northeastern counties/Sounds region with only a slight chance over the far south as any convection should wane during the late night hours. The northwestern counties remain in a Slight Threat of severe tonight with decent shear but diminishing instability after midnight. Lows tonight should be in the upper 60s to lower 70s. && .SHORT TERM /SUNDAY/... As of 335 PM Saturday...Frontal boundary will drift south through the CWA before dissipating Sunday afternoon as winds quickly come back around to S/SW in the afternoon. Any leftover boundaries along with heating as temperatures climb back toward 90 degrees will ignite a few scattered showers and thunderstorms during the afternoon, mainly inland. With respectable instability and weak low-level shear, some strong storms will be possible, but only expect scattered coverage and will keep PoPs at 30 percent inland and 20 percent coast. Highs Sunday will be 90-93 inland and 83-87 coast. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... As of 425 PM Saturday...An unsettled pattern will be the rule through the extended period as shortwaves/disturbances move through the region aloft, with weak frontal passages moving into the area and stalling Monday night and Wednesday night. These features will lead to continued low confidence through the period due to timing of shortwaves/frontal boundaries across area. Sunday night-Monday night...A weak shortwave will move through the region Sunday evening ahead of a stronger shortwave that will move through VA late Sunday night into Monday morning. Trended PoPs from high chance Sunday evening to slight chance after midnight. Models generally agree on more widespread convective threat with a stronger shortwave trough and surface cold front moving toward area during peak afternoon heating Monday. GFS/NAM forecast soundings indicate MUCAPE values of 2500-3500 with deep layer shear (0-6km) increasing to near 50 KT, thus increasing concern for strong to severe storms. SPC continues Day 3 Outlook of Slight Risk of severe for entire area. Brought PoPs down Monday morning due to lack of moisture and brief subsidence behind departing shortwave, then maintained PoPs in the 40 percent range for the afternoon. Guidance indicates low level thicknesses building to near 1430 meters, supportive of max temps 90-94 inland, with mid to upper 80s along the coast. Lows Monday night remaining muggy 70-74. Tuesday-Tuesday night...The frontal boundary is expected to stall across the area Tuesday morning, and wash out across area with additional short wave energy resulting in another period of mainly diurnally driven showers and thunderstorms. Tuesday afternoon convection could be similar to or exceed Monday`s activity, mainly because of better moisture focused along the stalled front and channeled shortwave/vorticity over the region coincident with peak afternoon heating. More cloud cover and lower thicknesses will keep max temps mainly in the 80s. Lows Tuesday night 66-70 inland to lower 70s coast. Wednesday-Saturday...Low confidence for this forecast period due to poor model continuity. 12Z guidance continues the wet trend for Wednesday and Wednesday night, though the ECMWF suggest the stalled boundary may be farther offshore than the GFS/GEM. Drying trend for Thursday looks good with front off coast. Higher chance PoPs for Friday with front lifting back north, helping to focus moisture over the area through Saturday morning. Max temps still in the mid to upper 80s for Wednesday and Thursday, then low 80s for Friday and Saturday due to cloud cover and showers/thunderstorms. Lows from mid 60s to lower 70s. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Short Term /through 18Z Sunday/ As of 615 PM Saturday...VFR through the TAF PD. Thunderstorms may impact the area after 10 pm, with KPGV seeing the best chance of thunder tonight. Storms may tempo limit vsbys to IFR/MFVR in heavy rain along with tempo gusty and erratic wind gusts. May need to add a VCTS or tempo TS with later updates after 02Z. Any storms move off and weaken late in the overnight with benign conditions through much of Sunday. Long Term /Sunday night through Thursday/ As of 410 PM Saturday...Sub-VFR conditions likely Sunday night as a weak front and upper level disturbance move through the area. Better chance for periods of sub-VFR with convective activity each afternoon and evening from Monday through Thursday. Less coverage for Wednesday and Thursday but sub-VFR could linger with front stalled over area. && .MARINE... Short Term /Tonight and Sunday/ As of 345 PM Saturday...Winds continue to be SSW/SW at 10-15 knots with a few higher gusts at late afternoon with seas at 1-3 feet. Frontal boundary will enter the far northern waters late tonight and will work its way south before dissipating Sunday afternoon as the winds quickly become S/SW again. Expect seas to perhaps rise to as high as 4 feet over the coastal waters tonight but should drop back to 2-3 feet on Sunday per latest SWAN/NWPS model. Long Term /Sunday night through Thursday/ As of 430 PM Saturday...Zonal flow with weak disturbances aloft will lead to several weak frontal intrusions into the area Monday night and again Wednesday night. Southern half of waters will mainly see SW winds 5-15 knots during period but northern waters will see some periods of shifting winds but with speeds less than 15 knots. Southern waters will see some periods of seas building to 4 feet for outer portions with stronger SW winds around 15 knots, otherwise seas mainly 2-3 feet during the extended period. NWPS and Wavewatch in good agreement through the medium range, with Wavewatch appearing reasonable for the extended seas forecast. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...CTC NEAR TERM...CTC/TL SHORT TERM...CTC LONG TERM...DAG AVIATION...DAG/CTC/TL MARINE...DAG/CTC
Area Forecast Discussion
National Weather Service Paducah KY
725 PM CDT Sat May 27 2017 .MESOSCALE DISCUSSION... Issued at 723 PM CDT Sat May 27 2017 Dynamic and complicated convective scenario remains in play across the WFO PAH forecast area. In coordination with SPC, the following counties that were in Tornado Watch # 275 that just expired were placed back into Tornado Watch #284 until 2 am CDT Sunday morning. Locations from south of Van Buren to New Madrid have seen scattered severe/non- severe thunderstorm activity, but the airmass still remains primed with ESRL HRRR CAPE of 3000-5000 J/kg2 with decent upward vertical velocities expected between 10 pm and midnight over the new counties included in the new Tornado Watch #284 for southern MO. There are still active storms moving across these southeast Missouri counties, so additional warnings may be possible earlier this evening. Reference SPC`s Mesocale disussion # 878 issued earlier this evening for more details on the storms in southeast Missouri this evening. The serial bowing segments moving through West Kentucky now should work stabilize further convective activity through the remainder of the evening. May need to shave off part of the current PDS from some of the Southern Illinois/Southwest Indiana counties along the Interstate 64 corridor. With boundaries still nearby, may hold these counties in the watch until expiration. && .UPDATE... Issued at 152 PM CDT Sat May 27 2017 Rapid adjustments made to reflect current activity across the WFO PAH Forecast area. Greatest concern at the moment will be the convective complex moving from East Central Missouri, then along and remnant outflow/frontal boundaries south of the Interstate 64 corridor...then again along the common borders of Southeast Missouri, Northeast Arkansas, West Kentucky and Tennessee. | UPDATE Issued at 1133 AM CDT Sat May 27 2017 Convection is developing along outflow boundaries and existing warm frontal boundary over Southern Missouri and parts of Southern Illinois and the Pennyrile of West Kentucky. Some local concern that some of these storms along the boundary may go severe severe before the main bowing line (developing derecho?) reaches the WFO PAH CWA later this afternoon and this evening. Waiting to see what SPC might do with the MDT risk area in their midday update. Also added Flash flood Watch for Carter/Ripley counties from 1 pm today through 7 am Sunday.(see hydro section). && .SHORT TERM...(Today through Monday night) Issued at 134 AM CDT Sat May 27 2017 New SWODY1 outlooks moderate risk for much of FA this pm/evening, with all svr wx hazards possible. AM storms to our west are modeled to affect western ptns FA later this morning, and may lay out a boundary and also blow off debris clouds that could stall development after daybreak. However, differential heating should mix the atmos up enough to allow super charge to take place, with high cape environ and steep mid level lapse rates revealed by model soundings. At some point during the pm hours, cap should break and convection become numerous to widespread, with associated moderate risk of svr extending from late pm into/thru the evening hours. Svr chances begin to diminish overnight as large scale instability is lost the farther east storms push away from source boundary/energy. Primary cold front does not make actual passage until Sunday evening, so until then, we`ll be continuing pops along/ahead of the boundary, and this includes a continued slight risk of severe again for mainly Sunday afternoon/early evening. .LONG TERM...(Tuesday through Friday) Issued at 134 AM CDT Sat May 27 2017 The extended period continues to be troublesome with models flip flopping the best chances for rain. Still dealing with another frontal boundary passage on Tuesday/Tuesday night. The GFS has been the most consistent with the timing of this feature but not as much on QPF. Still, believe that precip chances need to be included for that time frame given the consistency of this signal and the consistency of the GFS ensemble precip means. At this time our confidence does not warrant anything more than slight chances. The ECMWF was never that excited about Tuesday`s rain prospects and still isn`t. Instead, the 12Z ECMWF brings a front down into the area on Wednesday through Thursday. That is the exact same time that the GFS brings in a reinforcing sfc high pressure system that dries us out. However, the 00Z ECMWF is back to looking like the GFS with the drier weather on Wednesday with the incoming sfc high. The early part of the extended forecast is going to be hinged on exactly what this large upper level low over the upper Great Lakes region/eastern Canada does and the timing and strength of impulses rotating around it. For now, leaning toward the more consistent GFS for guidance. Given the above discussion, POPs will be low Tuesday through Thursday given uncertainty`s in the model signals. There has been a stronger signal for more wet weather as we head into the latter half of the week. However, the upper level pattern is not being consistently resoled by the models very well at all. Yesterdays runs indicated more of a southwesterly flow pattern setting up and now the upper flow stays more west northwesterly through Friday. We will continue to have POPs for late week, but work will need to be done on fine tuning these chances as models grasp a better handle on things. && .AVIATION... Issued at 152 PM CDT Sat May 27 2017 Current 18z Saturday TAF issuance will be a challenge with mutiple boundaries focusing VFR to IFR changing conditions. Base forecast includes thunderstorms in each TAF location. Main concern within the next six ho9urs will be the KEVV, KCGI, and KPAH TAF locations for lowered visibility. && .HYDROLOGY... Issued at 1133 AM CDT Sat May 27 2017 WPC recently upgraded parts of Southern Missouri in a Moderate Risk of excessive rainfall through today and tonight. Given the antecedent rainfall this morning, combined with the expected position of the frontal boundary and outflows today, felt it was prudent to add Carter and Ripley counties to the Flash Flood Watch later this afternoon and tonight. Depending on the propagation of the convection along the boundary and the southern end of the expected wind-damaging MCS, may need to extend the Flash Flood Watch to Wayne and Butler counties as well. Will monitor the progression of the storms this afternoon. Minimum rainfall of 1-1.25 inches is likely...with higher amounts possible. Given the flashy nature of runoff and the terrain, as well as the potential for higher public presence outdoors this weekend, decided to go ahead with a Flash Flood Watch for Carter and Ripley counties from 1 pm today through 7 am Sunday. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...Flash Flood Watch until 7 AM CDT Sunday for MOZ107-108. IN...None. KY...None. && $$ MESOSCALE...Smith UPDATE...Smith AVIATION...Smith HYDROLOGY...Smith
Area Forecast Discussion
National Weather Service Shreveport LA
943 PM CDT Sat May 27 2017 .DISCUSSION... Surface low across Red River valley extending into eastern Oklahoma generating severe thunderstorms across much of central and eastern Oklahoma. HRRR model suggests bulk of the convection to remain out of the ArkLaTex through 3 AM before a cold front slides south across the I-30 corridor. As convection moves south with the front, atmosphere becomes less conducive to maintain severe thunderstorms as noted by an enhanced risk across McCurtain county and a slight risk across much of northeast Texas and Southern Arkansas. Current forecast is on track, no updates at this time. /05/ && .PREV DISCUSSION... /issued 733 PM CDT Sat May 27 2017/ AVIATION... For the ArkLaTex, VFR with a touch of haze until sunset. Winds are S 5-15KT and will become SW for Sunday. Aloft we are SW 15-35KTS. MVFR stratus will meet convection from the N before daybreak with a cold front moving in our direction bringing early widespread shwrs/tstms from 09-13Z. The cold front will move closer but not through until Sunday night. So expect more dvlpmt of tstms for the p.m. hrs. Fropa will shift surface winds and not much else early Monday. The boundary will slowly lift back North into midweek./24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 75 87 69 81 / 30 40 60 40 MLU 74 89 70 81 / 20 30 60 60 DEQ 72 82 61 85 / 80 40 40 10 TXK 73 83 65 83 / 60 40 60 20 ELD 74 84 65 81 / 50 40 60 40 TYR 75 86 68 82 / 40 40 60 30 GGG 75 85 68 81 / 30 40 60 30 LFK 77 91 72 81 / 10 30 70 60 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 05/24
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday) Issued at 316 PM CDT Sat May 27 2017 Thunderstorms moved east of the area early this afternoon which resulted in mesoscale subsidence and drying across northeast Kansas. This was evident on the 18Z special TOP sounding which was dry and relatively stable. The airmass may recover enough to support continued thunderstorm chances with a low risk of severe weather mainly from large hail. Mid-level lapse rates were around 8.5 C which favored hail if there was enough low-level moisture to produce storms. What storms we see will likely be slightly elevated and not surface based. The area of extreme instability coupled with favorable shear should remain south of our area. Expect all of the thunderstorms to exit the area by early evening. Model soundings suggest saturation below the frontal inversion tonight which supports cloudiness. Recent runs of the HRRR keeps showers together as they move out of Colorado and across Kansas late night. Will not alter the forecast based on this due to lack of confidence, but it is something to watch. .LONG TERM...(Sunday night through Saturday) Issued at 316 PM CDT Sat May 27 2017 Overall, the upper air pattern remains PNA with west coast ridging and an upper trough over the upper Mississippi valley. Cool Canadian air should move into Kansas tonight and Sunday in association with a polar high pressure system building south through the plains. This should result in dry and relatively cool weather through the balance of the holiday weekend. The surface ridge eventually moves east by midweek allowing for return flow and increased moisture and instability. This along with weak disturbances is enough to support small pops in the extended forecast. Temperatures should slowly warm to slightly above normal by the end of the forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 603 PM CDT Sat May 27 2017 Will keep TAFS VFR at this time with the expectation that any precip with the southern KS overnight complex will remain south of the sites given dry advection at 850mb. Only other potential issue would be some MVFR VIS issues around TOP however at this time boundary layer mixing and weak dry air advection makes fog development uncertain at TOP and unlikely at FOE or MHK. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Johnson LONG TERM...Johnson AVIATION...Omitt