Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/25/19

Area Forecast Discussion
National Weather Service Denver/Boulder CO
724 PM MDT Wed Apr 24 2019 .UPDATE... Issued at 656 PM MDT Wed Apr 24 2019 Some minor adjustments for tonight. The HRRR and RAP13 both indicate some weak showers or maybe a thunderstorm could develop along the boundary that could push into the Denver area 04-05z. Weak CAPE present on the 00Z KDNR and radiometric soundings this evening. Only adjustment to broaden the slight chance of showers/thunderstorms a little further south to included the Denver area this evening. Also could see some light showers activity develop late tonight following the passage of a cold front that appears to move into Denver around 08z. Some weak post frontal upslope coupled increasing low clouds until around 12z. For this reason, I added slightly higher pops for the Denver area from 09-12z tonight. && .SHORT TERM...(This evening through Thursday) Issued at 251 PM MDT Wed Apr 24 2019 Weak high pressure ridging aloft over Colorado this afternoon under a light to moderate northwest flow aloft. Radar showing some light showers over the mountains and higher terrain but showers are dissipating over the plains. Airmass is only marginally unstable along with limited moisture. Expect showers to remain on the light side and generally confined to mountains and higher terrain areas near the wyoming border and the Palmer Divide. The main feature will be a cold front which will sweep across northeast Colorado from the north later tonight. Current frontal position is across Montana and will slide into the Denver Metro area between 08-10z time frame. Could be some focus of showers and storms along the front especially along our northern border areas, closer to best ascent. Will have scattered coverage of storms further north, with lesser chances further south and west. Low clouds expected to lag behind the front a few hours and fill in across the plains before daybreak. Temperatures on Thursday expected to be cooler behind the front. Any showers/storms will likely be confined to mountains and elevated terrain areas on Thursday afternoon. The far northeast plains will be too dry and stable for any storms. .LONG TERM...(Thursday night through Wednesday) Issued at 251 PM MDT Wed Apr 24 2019 Weak ridging in the west-northwest flow aloft will move across Colorado Thursday night. Other than a few early evening showers in the mountains, expect dry conditions overnight. This ridge will move off to the east Friday as a quick moving trough tracks across the Northern and Central Rockies. Lapse rates steepen and CAPE climbs up to 500 J/kg during the afternoon. Airmass not that moist with dew points in the 30s. Expect scattered showers over the mountains and foothills with isolated high based storms over plains. Subsidence and drying will prevail Friday night behind the exiting wave. This may bring windy conditions to the foothills and areas near by. A dry and mild west-northwest flow aloft will be over the area Saturday. A lee side surface trough will form over eastern Colorado. The GFS shows thunderstorms forming along the surface trough Saturday evening. Other models remain dry. Dew points will struggle to climb out of the 20s, so will leave the forecast dry for now. On Sunday, flow aloft turns westerly. Models start to diverge on Sunday with the ECMWF showing a cold front pushing south during the day Sunday while the GFS is later with this feature. Airmass moistens behind the front and should provide enough lift for scattered showers. For Monday through Wednesday, the weather turns cooler with better chances for precipitation. A closed low off the California coast weakens and lifts northeast across the region. Models still disagree when this trough will track over Colorado. In addition to the trough, lift from the jet stream should also produce showers at times. Will go with cool temperatures and a good chance for showers Monday and Tuesday. By Tuesday night, the trough will be east of the area. A new system over the Pacific Northwest will drift southeast towards the Central Rockies Wednesday. This system may bring another round of showers to the area for Wednesday and Wednesday night. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 656 PM MDT Wed Apr 24 2019 Surface winds expected to remain light from the north/northeast this evening. The high resolution models hint at some potential showers developing along a boundary that is expected to move into the Denver area 04-05z. Will keep vcsh in the tafs at that time with broken mid level ceilings and VFR conditions until 09z. Later tonight, a cold front will push through terminals between 08-10z tonight, a bit later that current forecast. Peak wind gusts with the passage of the cold front could be in the 20-25 kt range around 08z. Expect low clouds (MVFR/IFR) to develop a after cold frontal passage along with some brief light rain showers, between 09-14z then improving to LIFR ceiling in the 4-5 thousand feet AGL from 14-18z then VFR Thursday afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Entrekin LONG TERM...Meier AVIATION...Cooper
Area Forecast Discussion
National Weather Service Quad Cities IA IL
946 PM CDT Wed Apr 24 2019 .UPDATE... Issued at 935 PM CDT Wed Apr 24 2019 Added fog to the forecast for late tonight into early Thursday morning, roughly over the SW two-thirds of the forecast area where dewpoints are in the lower 40s to lower 50 F. Winds overnight will be light and variable under an area of high pressure thereby promoting low-level saturation. GOES microphysics imagery showed stratus clouds from Iowa City to Macomb and points to the southwest. These clouds may expand northward overnight, transitioning into areas of fog late as temperatures cool. Hi-res models are aggressive on potential for dense fog and it`s something we`ll have to keep an eye on tonight. As of 930 PM, fog has yet to form in our area. The closest dense fog observation is to the south, with the visibility down to 1/4 mile in Pittsfield, Illinois. && .SYNOPSIS... Issued at 316 PM CDT Wed Apr 24 2019 While today certainly is not particularly hazardous as far as current weather goes, it`s certainly fraught with challenging details, including chaotic flow, low clouds, high based narrow swaths of measurable rain, and daytime light fog. This is resulting in an afternoon improvement from a wet dreary day to one that may still be quite pleasant in some locations in the west, south, and east, while the north central, near the Mississippi River, remains sunny, and has been in the lower to mid 60s since Noon. The weak low level flow around this high based vort has certainly created this chaotic flow, as it allowed the weak precipitation process to saturate the initially dry mid levels. The shallow stratus has only been found on the northwest flank of any rain, likely favored there as the cool moist low levels to the southeast of it have been advecting into that region all day. Now that rain processes have moved to the east, that support mechanism should break down and allow clearing. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 316 PM CDT Wed Apr 24 2019 Clearing conditions should be the trend this evening, with some potential for stratus and mid clouds to hang on in the southwest and south, possibly through the night, as the flow increases from the south tonight. Lows tonight are challenging with cloud cover, and may vary from mid 40s northeast to upper 40s central and west. Tomorrow, the cold front should move through from west to east, from mid morning to mid afternoon, with a wind switch initially seeing the main impact. Saturation appears mainly post frontal, with showers in the cooler air, most likely light. This band of showers should be less than a tenth of an inch in most areas. There is a low chance of reaching convective temperature prior to the front hitting in the southeast, and for those locations, I have added an isolated thunder risk during the afternoon. This is a low threat, but at least is hinted at by the Namnest and extended RAP model runs. Convective temperatures of the mid 70s are possible, but clouds may keep that a low threat. Otherwise, look for mid 60s to lower 70s highs from west to east. .LONG TERM...(Thursday Night through Wednesday) ISSUED AT 316 PM CDT Wed Apr 24 2019 Weather pattern will turn quite active over the weekend and into next week. The potential for heavy rainfall is very real. However, there is considerable uncertainty on where and how much rain could fall. Thursday night Assessment...medium to high confidence The cold front will exit the area and rain will end along and east of the Mississippi during the evening hours. Strong winds immediately behind the front are very possible during the early evening hours. Dry conditions are then expected after midnight. Friday and Friday evening Assessment...high confidence Quiet, dry but windy conditions will be seen on Friday with temperatures at or slightly below normal. Although soil conditions are quite moist, humidity levels will become quite low late Friday morning and afternoon which may result in an enhanced fire risk for any grassy areas that have not yet greened up. Late Friday night through Saturday Assessment...high confidence on a storm system affecting the area. Low to medium confidence on placement of and rainfall amounts. The first storm system with the potential for heavy rain will move through the Midwest. The models have been somewhat consistent with this storm system in placing the heaviest rainfall from the MN/IA border into southern Wisconsin. However, recent GFS runs have trended slightly further north while the FV3 has trended slightly south. Regardless of the model solution all models have been pointing to Saturday as when the main rainfall will occur. The model consensus has slight chance to chance pops late Friday night and likely to categorical pops on Saturday. Saturday night on... Saturday night Assessment...medium to high confidence The early weekend storm system will exit the area Saturday evening followed by dry conditions late Saturday night. The model consensus has slight chance to chance pops for Saturday evening. Strong winds Saturday evening will usher in much colder temperatures with a risk of freezing temperatures in the highway 20 corridor. Sunday Assessment...medium to high confidence The cold front that moved through the area with the weekend storm system will begin moving back north toward the area on Sunday. The model consensus has mainly dry conditions Sunday due to the dry atmosphere over the area. Temperatures will average below normal. Sunday night through Wednesday Assessment...high confidence that two separate storm systems will impact the Midwest. Low confidence on storm track and potential rainfall amounts. The global models are highly varied on timing and tracks of two additional storm systems. Likewise the location of and rainfall amounts are also highly varied. The GFS takes both systems from the IA/MO border into northern Illinois with heavy rain over the area. The ECMWF as a stalled front further south and takes the first system from Missouri into central Illinois with the second system moving from western Iowa into Minnesota Tuesday night into Wednesday. The CMC global takes two separate systems from the IA/MO border into central and northern Illinois with heavy rainfall. The FV3 takes the first system from Iowa to the IL/WI border. The second system is much further south going from Missouri into southern Illinois. Given all these differences in track and timing, the model consensus has chance to likely pops Sunday night and Monday, slight chance to chance pops Monday night, chance to likely pops Tuesday and Tuesday night, then chance pops on Wednesday. Although there are rain chances from Sunday night through Wednesday, it will not rain continuously. There will be periods of dry weather the first half of next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) ISSUED AT 705 PM CDT Wed Apr 24 2019 Clear skies and decoupled winds overnight may lead to areas of fog late tonight in Thursday morning, which could become locally dense. Mentioned fog in TAFs but held off on dense fog until confidence increases, and will let later shifts reassess with 06Z TAF cycle. For Thursday, expect increasing cloud cover with brief MVFR ceilings possible, NW winds developing behind a cold front, and periods of light rain or showers -- mainly in the afternoon/evening. && .HYDROLOGY... Issued at 1117 AM CDT Wed Apr 24 2019 The Mississippi is currently rising from LD11 down to LD15. The river will begin rising again on Thursday from LD16 down to LD17. Downstream of LD17 the river will begin rising again Friday into Saturday. The new forecasts for the Mississippi have slightly lower crests from LD11 down through LD17. HOWEVER, the current 7 day Mississippi forecast does not, repeat, does not take into account predicted rainfall from Friday through Tuesday. The weather forecast models are suggesting the possibility of heavy rainfall. Depending upon where and how much rainfall occurs crest timing and crest forecasts are subject to change. If the rain occurs on or just ahead of the crest then crest forecasts have the potential to go higher than forecast. The weather models are suggesting the heaviest rainfall from the early weekend rain would occur from the IA/MN border into southern Wisconsin. If this location is correct it would occur behind the crest and would slow the rate of fall on the Mississippi. There is much more uncertainty regarding the second round of potential heavy rain late in the weekend and early next week. The weather models continue to offer different tracks for the storm system and potential rainfall amounts. Individuals with interests along the Mississippi are strongly urged to pay attention to future weather and river forecasts over the next week. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...Uttech SYNOPSIS...Ervin SHORT TERM...Ervin LONG TERM...08 AVIATION...Uttech HYDROLOGY...08
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1006 PM CDT Wed Apr 24 2019 .NEAR TERM [Through Tonight]... Water vapor imagery shows a strong upper low over central Texas. 00Z upper level analysis has a strong nearly 100kt jet core coming into the area with the best divergence ahead of it where there has been strong/severe convection. There is still some strong divergence aloft that should move over SE Texas tonight but capping has held fairly strong and instability has decreased quite a bit with loss of heating. The boundary layer has also become more turned over with ongoing and previous convection. There is still some chance at some storms through the morning hours but the threat looks fairly small at this point. There might be enough lift along a front that pushes through afternoon midnight to trigger some convection so forecast will have some chances for storms continuing. HRRR trends along with WRF show this possibility. Again any storms that do form may become strong but should remain below severe limits. After the storms tonight, tomorrow looks fairly pleasant with northwest winds and drier air moving into the region. Overpeck && .PREV DISCUSSION /Issued 636 PM CDT Wed Apr 24 2019/... .AVIATION [00Z TAF Issuance]... Forecasting line of storms will prove difficult tonight as strong/severe storms run into capped atmosphere over Southeast Texas. Cap is eroding, but unsure if it will be enough for severe storms to continue much deeper, especially as storms seem to be moving more quickly than in models. This is a long way of saying that amendments may be frequent tonight as this dynamic situation evolves. Eventually, sometime in the ballpark of mid-day tomorrow, look for VFR conditions to return with northwesterly winds. && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 59 80 60 83 60 / 100 0 0 0 0 Houston (IAH) 63 81 62 85 62 / 70 0 0 0 0 Galveston (GLS) 67 79 68 80 68 / 70 20 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 7 AM CDT Thursday for the following zones: Waters from Freeport to Matagorda Ship Channel TX from 20 to 60 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$ DISCUSSION... NEAR TERM...Overpeck
Area Forecast Discussion
National Weather Service Lincoln IL
846 PM CDT Wed Apr 24 2019 .UPDATE... Issued at 845 PM CDT Wed Apr 24 2019 Have made some minor tweaks to the grids to match up with precipitation trends. Currently between waves moving along boundary to our south with pcpn confined to south of I-70. As the night goes on scattered showers are once again expected to pop-up generally southeast of I-72/Danville after midnight as the next wave approaches the midwest. Fog may become an issue later tonight, particularly along and west of I-55 where 00z HRRR, RAP, and 01z LAMP all depict low vsbys. They have backed off some in coverage in the last few runs so may be patchy. Thats what we have running in the grids and that stills seems reasonable. && .SHORT TERM...(This evening through Thursday) ISSUED AT 245 PM CDT Wed Apr 24 2019 IR satellite imagery shows 3 waves (northern IL, southern KS, and southwest TX). Movement of these waves will be enough to keep plenty of pcpn over the southern 1/2 of IL through Thursday. IL wave to continue to move off to east as pcpn develops in overrunning pattern over the semi-stationary front in the OH river valley. Showers and storms over Mo to move northeast, mainly over southeast IL overnight, all ahead of the KS wave. Models strengthen the TX wave, developing a significant low center that tracks into AR, increasing pcpn ahead of it and with showers reaching into southeast IL through the day Thursday. Cold front to sweep into IA by Thursday morning and move into IL late will bring a chance for some additional scattered showers Thursday afternoon and evening. .LONG TERM...(Thursday night through Wednesday) ISSUED AT 245 PM CDT Wed Apr 24 2019 Dry conditions on Friday. This will not last long as another low center to move from the rockies and move over northern IL on Saturday. Then overrunning showers develop on Monday ahead of another low Monday, with the rain continuing into Wednesday til the cold front passes. As a result, temperatures will remain on the cool side for late April into next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 650 PM CDT Wed Apr 24 2019 Waves continue to advect along the boundary to our south bringing oscillating vsbys and lowered cigs to central Illinois terminals, particularly KSPI and KDEC. Conditions have been significantly worse in K3LF and KPPQ over the past few hours then KSPI, but trends have gone downward with KSPI currently on the edge of IFR Cigs and vsby starting to drop. RAP, LAMP, and HRRR all suggest vsbys and cigs will be an issue through midmorning from I-55 west. For now will bottom out at 1SM and stay out of LIFR category but this will need to watched closely. At most sites, will use VCSH to indicate the enhanced precip chances in the area with the final wave during the day Thursday. With KDEC closest to boundary will go with a period of predominant precip there. Front will move in late Thursday and bring a wind shift and a gradually clearing trend. Will go VFR by the end of the TAF valid period at KPIA as drier air starts moving in. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barker SHORT TERM...Goetsch LONG TERM...Goetsch AVIATION...Barker
National Weather Service Jackson KY
1051 PM EDT Wed Apr 24 2019 .UPDATE... Issued at 1051 PM EDT WED APR 24 2019 Evening radar trends and model data support lowering the POP for tonight and into Thursday morning. The only values in the likely category for tonight are now at the northern tip of the forecast area, mainly in Fleming County. Lightning is diminishing and may be gone by the time the only currently active cell makes it to our area. Have maintained a slight chance of thunder only in Fleming county. UPDATE Issued at 633 PM EDT WED APR 24 2019 Based on observed trends, the precip potential is slower to arrive this evening than was forecast. The GFS was the most aggressive with bringing it into our area, and it appears the less aggressive NAM and HRRR have a better handle on things at this point. If this continues to be the case, the precip potential will be a bit further north this evening. The forecast has been updated trending that way. && .SHORT TERM...(This evening through Thursday night) Issued at 329 PM EDT WED APR 24 2019 An area of surface low pressure and its associated fronts will be the epicenter for our weather over the short term portion of the forecast. Currently this area of low pressure is located over southern Illinois. From this stretches a frontal boundary eastward, which has remained draped over NE Kentucky through much of the morning and early afternoon. This area of low pressure is expected to finally begin shifting northeastward this evening/overnight, allowing the frontal boundary to lift northward as a warm front. Meanwhile, a cold front extends southwest of the low and is expected to begin traversing far western Kentucky during the overnight. Another stronger area of low pressure will then begin making its way towards the Mid-Mississippi Valley overnight as well, reaching far western KY by 21Z Thursday. The cold front will continue to traverse eastern Kentucky Thursday night as the area of low pressure continues to shift northeastward across the state, exiting into Ohio by Thursday night. As for sensible weather, expect SW winds to be on the increase especially after the frontal passage lifts northward as a warm front this evening/overnight. Moisture associated with the approaching low will lead to increased clouds as well as rain chances, mainly across the northern CWA. Clouds will provide insolation overnight, so lows will only fall to the upper 50s to around 60. Then for Thursday, the area of low pressure will pass by north of the CWA while the cold front approaches from the west. This will overspread the rain chances across the CWA throughout the day, especially across the northern and western CWA. Afternoon heating may lead to some instability and thunderstorm chances, but not expecting anything strong. Highs will generally be in the mid and upper 70s, though northern Ky could see lower 70s. Showers and thunderstorms will then increase overnight Thursday night as the front passes across the CWA and the next area of low pressure moves across the state. QPF will be quite a bit higher during this period, especially along the Bluegrass region. For the 24 hour period ending at 18Z Friday, between 0.66 and 1.25 inches of rainfall are forecast across eastern KY. .LONG TERM...(Friday through Wednesday) Issued at 320 PM EDT WED APR 24 2019 The extended looks to feature alternating periods of wet and dry weather, as a couple of low pressure systems and a ridge of high pressure affect area weather. The strongest of the storm systems will be moving through the area Friday and Friday evening, and will bring a good soaking rain to eastern Kentucky. Saturday and Sunday look mostly dry, with a few rain showers possible across the northwestern portion of the area Saturday afternoon and evening. After dry weather Sunday and Sunday night, another weather system is forecast to bring more rain to eastern Kentucky Monday and Monday night. We may even see a few thunderstorms Monday night. Tuesday and Tuesday night look to be mostly dry, with a few rain showers possible along the Virginia border and along and north of I-64. The Bermuda high will occasionally advance northward, giving us dry weather Sunday and Sunday night, and then southward, allowing for wet weather on Saturday and to start the new work week. Temperatures will exhibit a bit of range in the extended, with max values in the mid to upper 60s expected on Friday, and the upper 60s to lower 70s on Saturday and Sunday. We can expect a good warm up to begin the new work, as southerly winds allow for max temperatures ranging from the mid 70s to lower 80s. Nightly lows will generally be in the 40s and 50s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 815 PM EDT WED APR 24 2019 Mainly VFR conditions are expected through the period, with a couple of possible exceptions. Showers could bring sub-VFR conditions near/north of a KIOB-KSYM line overnight tonight, and showers and thunderstorms may result in sub-VFR conditions near/west of a KSME-KSYM line near the end of the period late Thursday. However, the probability at TAF sites is too low to warrant anything other than VCSH or VCTS at KSYM and KSME. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...JMW LONG TERM...AR AVIATION...HAL
Area Forecast Discussion
National Weather Service Lake Charles LA
936 PM CDT Wed Apr 24 2019 .UPDATE... If you have been following along this evening the situation has been settling down some, as organized line of earlier severe storms over Texas has been on a weakening trend. with just some disorganized showers and isolated thunderstorms entering the forecast area of southeast Texas. The 25/00z upper air sounding from KLCH was not very impressive as far as severe weather or heavy rainfall parameters. Looking ahead, some of the guidance like the RAP13 is still bullish on the dynamics after 25/06Z with good shear, CAPE, and PWAT values. However, there is still some inhibition noted with small cap around 85H, and mid level dry air intrusion, which is possible looking at latest water vapor imagery. Therefore, these factors could keep strength of the activity in check. SPC has lowered the severe risk for the remainder of the night to the Marginal level (5 percent wind damage, 2 percent tornado.) Also, WPC has lowered the excessive rainfall risk to the Marginal level (5-10 percent.) 25/00Z 50 percentile probabilistic QPF values (most likely) and WPC operational QPF values are down to 1/2 to 1 1/2 inches on average with only the 90th percentile (reasonable worse case scenario) showing 2 to 3 inches on average with some local higher amounts. With that being said, the latest HRRR from 25/01Z still insists on a regeneration of an organized line of healthy storms around 25/12Z along the Sabine River, with individual cells still showing rainfall rate potential on the order of 1-2 inches per hour. That and the still impressive RAP13 forecast soundings, don`t want to totally down play everything, but the risk for the severe weather and heavy rainfall is lower for tonight than it was looking like at this time yesterday or earlier today. Will modify the grids some based on the latest hi-res guidance and radar trends. Rua && .PREV DISCUSSION... /issued 658 PM CDT Wed Apr 24 2019/ DISCUSSION... 00Z TAFS AVIATION... Ceilings range from VFR to MVFR across the region at this hour with MVFR CIGs expected to become more dominant after sunset. A developing squall line will approach from the west overnight along the leading edge of a cold front. Some of these storms will have the potential to be strong to severe with strong and gusty winds along the leading edge of the line. Visibility reducing heavy rain will also be possible within some of this activity. Winds behind the front will turn westerly and remain gusty. Ceilings will lift to VFR Thursday afternoon, but scattered overrunning showers will continue across the area through the evening in the wake of the frontal passage. Jones PREV DISCUSSION... /issued 346 PM CDT Wed Apr 24 2019/ DISCUSSION... Mid-afternoon sfc analysis shows a cold front stretching from low pressure near the Ozarks through the ArkLaTex to the cntl TX Hill Country. Water vapor imagery indicates a strong shortwave crossing the srn Plains/TX Big Bend with an initial vort ahead of it crossing cntl TX at this time. Regional 88Ds are showing plentiful showers/storms associated with these features out to our west...a few strong to severe storms have been noted and a Severe Thunderstorm Watch continues across cntl TX. Closer to home, sfc obs indicate mostly cloudy skies with seasonal temps ongoing, but no rainfall has been reported with the light returns making their way across the forecast area so far this afternoon. Our anticipated potential severe weather event still looks on track for tonight. Convection currently ongoing out to our west should continue to track ewd/enewd with the disturbance aloft ahead of the primary shortwave. High res models have been consistent in indicating a line of thunderstorms mainly in association with a pre-frontal/outflow boundary moving into our wrn zones late this evening, then traversing across the forecast area through the overnight hours, departing lower Acadiana by mid- morning Thursday. Synoptic-scale models show more of a slower moving, more widespread convection solution...and POPs through tomorrow are kind of a blend of the two. Forecast soundings continue to advertise the threat for severe weather with improving moisture through the column/good CAPE, shear and lapse rates. Primary threats remain damaging wind gusts and possibly large hail. Tornado threat doesn`t look as good, but a tornado or two certainly cannot ruled out, primarily along the line as it moves through overnight. Guidance QPFs continue to inch downward with time with mean values topping out under 3 inches...certainly localized higher amounts will be possible, but for now have elected to hang onto any flood-type watches. Once the showers/storms depart the region tomorrow afternoon/early evening, dry weather in wake of the sfc front/shortwave aloft looks to take hold through the weekend and into early next week. Another weaker disturbance is progged to cross the nrn tier of the country over the weekend, dragging a sfc boundary swd toward the region...however all solutions are in agreement this afternoon that the front will hang up north of the forecast area with any precip not expected much farther south than the I-20 corridor. Next rain chances don`t enter the picture until the very end of the forecast period...and then only for the far wrn the next srn stream system crosses the swrn CONUS, helping spin up a sfc low over the Plains, then drag a cold front toward the forecast area. MARINE... Caution headlines have been inserted for the outer waters west of Intracoastal City as winds strengthen to 15-20 knots by late afternoon, then linger through the overnight hours. Thereafter, no flags are expected on the coastal waters through the remainder of the forecast period. && .PRELIMINARY POINT TEMPS/POPS... AEX 66 78 59 80 / 80 60 20 0 LCH 69 79 63 82 / 80 70 10 0 LFT 69 79 62 82 / 70 80 20 0 BPT 68 80 62 84 / 80 40 10 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...Small Craft Exercise Caution until 7 AM CDT Thursday for GMZ470- 472. && $$ PUBLIC...07
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
555 PM CDT Wed Apr 24 2019 .SHORT TERM... 247 PM CDT Through Thursday Night... Through the next 36 hours, there are a couple periods of precipitation, with one being spotty light showers the rest of this afternoon and tonight, then two being a period of showers...with an outside chance for thunderstorms...late Thursday afternoon and evening. Satellite imagery this afternoon depicts a sheared and weak wave, but still well-defined and persistent (more so pesky), across northern Illinois. This has provided enough isentropic lift and moisture return above 800 mb for scattered light showers and sprinkles across mainly north central Illinois so far. Some of this current activity will spread/re-develop eastward through this evening as the forcing does, with northwest Indiana possibly seeing spotty light showers all the way into early Thursday morning. Clouds will also be very slow to depart and confidence on low temperatures is somewhat low, but expecting little movement this evening. Clouds should linger into the morning across southern and eastern parts of the CWA. The upper low across Texas this afternoon will translate northeast into the Lower Ohio River Valley on Thursday. Meanwhile a northern stream impulse and associated cold front will approach the area and enter north central Illinois during the mid to late afternoon. Both areas of forcing in the southeast and northwest will potentially support showers, with a "squeeze" in the middle of the CWA that will likely be precipitation free through the afternoon. The northern stream cold front will accelerate into the area during the evening as mid-level phasing occurs between the systems. Deeper ascent and mid-level frontogenesis immediately behind the front look to support a decently wide axis of showers developing across northern Illinois into the evening. Convection allowing and other higher resolution guidance support this in their QPF solutions and have trended upward through today. It is not impossible to have isolated thunder too given a region of conditional symmetric instability hinted at by end of current RAP run and seen on the NAM run. With at least a few CAMs showing 40+ dBZ echoes, there could be some brief heavier showers in the evening. Activity should end from west to east late in the evening into the overnight. Temperatures on Thursday have potential to be into the lower to mid 70s ahead of the front, but clouds could and likely will be somewhat of a factor for at least part of the day. Also, a lake breeze is likely to develop in the otherwise light boundary layer flow ahead of the front to keep lakeside areas cooler during the afternoon. Behind the front, winds will turn sharply north with a several hour period of 20+ mph gusts favored. MTF && .LONG TERM... Friday through Wednesday... 235 PM...Primary forecast concern is with a system to affect the area Saturday/Saturday night...with an unsettled pattern early/ mid next week. A weak ridge of high pressure will move across the area on Friday with a strong low pressure moving from the central Plains across the area Saturday evening. The models are in overall fair agreement with the track of this low right across the cwa with some minor timing differences. Rain looks to spread across the area around/shortly after daybreak Saturday. Temperatures will be tricky...especially across the north with east flow briefly going southerly and then shifting northerly with the passage of the low. This could mean a brief warm up through the northern cwa with most of the day north of I-80 fairly chilly. Didn/t get to fancy with temps yet but this will likely require further refinement as this time period approaches. The models continue to show a swath of accumulating snow north of the cwa with this system. But a southern shift to this system could bring the snow potential further south. Its still possible that a few snow flakes mix in on the back side of the system Saturday night. Though it appears that much of the qpf will have ended by this time. The gradient will tighten as the low departs with high pressure building across the Western Great Lakes and the speed of the low will add to a short period of potentially very strong winds centered around 06z Sunday. Forecast soundings would support wind gusts into the 40-45 mph range. Did not go this strong yet...but this time period will also need to be monitored for strong winds. A series of low pressures may affect the area early/mid next week with several days of cooler easterly flow...periods of showers... and potential large temp differences from north to south across the cwa. cms && .AVIATION... For the 00Z TAFs... Light radar returns falling across the region continue to be mainly just virga as very dry air remains in place. Small chance some terminals may see a trace of precipitation, so did leave VCSH in the TAF for the next couples hours. Light easterly winds will remain in place for the rest of the night. Pleasant conditions are expected Thursday, but there will be a lake breeze developing in the afternoon. Expect that to impact wind directions at MDW after 20z and ORD after 22z. Showers will commence mainly after 00z Thursday evening across the region with flight categories staying MVFR or better. MM && .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 Aviation
National Weather Service Saint Louis MO
657 PM CDT Wed Apr 24 2019 .SHORT TERM... (Through Late Thursday Afternoon) Issued at 346 PM CDT Wed Apr 24 2019 An upper level trough stretching from southern Iowa down through southwest Texas into Mexico is moving slowly eastward this afternoon. Models are in good agreement that the trough will force low level cyclogenesis over Texas tonight along the front which has been nearly stationary from Texas up through Arkansas into the mid Mississippi Valley. The resulting closed surface low is forecast to ride up along the front overnight tonight and Thursday...moving into the lower Ohio River Valley by 00Z Friday. Guidance continues to show weak to moderate low level moisture convergence through the night tonight in southwest flow at 850mb ahead of the trough. While moist of the resulting convection will likely stay over far southeast Missouri and Kentucky, there will probably be areas of light rain tonight as a result of this moisture convergence...mostly confined to areas along and southeast of I-44 in Missouri and I-70 in Illinois. The RAP is showing a bit of elevated instability across southeast Missouri into southern Illinois as well, so a few rumbles of thunder aren`t out of the question either. Also of note tonight: visibility guidance gets very low over a wide swath of the forecast area...mainly along and north of I-70. Dense fog with visibility less than 1 mile is possible, and conditions may warrant a dense fog advisory, though I do not have enough confidence yet to issue one at this time. Low level moisture convergence increases sharply on Thursday morning as the center of the surface-850mb low moves into northeast Arkansas. There will likely be a sharp cut off to the resulting precipitation in Missouri and Illinois Thursday...and right now that cut off looks to be just southeast of I-44 through southeast Missouri into southwest and south central Illinois. There may be some potential for heavy rain and flooding if the rain persists through the day...though it`s not clear just yet whether the heavy rain threat will reach as far north as our southeast Missouri counties. For now we will just continue to monitor the heavy rain potential. Carney .LONG TERM... (Thursday Night through Next Wednesday) Issued at 346 PM CDT Wed Apr 24 2019 Period begins with the southern stream low, that is expected to lift NE into the area tomorrow, moving east out of the area. Meanwhile, an upper trof within the northern stream and associated surface cold front will push south into the area. With strong CAA with this front and good upper level support, believe showers should develop along and just behind the front into the evening hours. For the remainder of the forecast period, model solutions are in fairly good agreement. However, there are differences in timing of an upper low opening and ejecting into the Plains late in the period. While there are some differences from one cycle to the next, the overall trends are similar. With zonal to slightly ridging flow, have trended near or just above median temperatures through the end of the forecast period. PoPs remain near the low chance range with more uncertainty on timing. Tilly && .AVIATION... (For the 00z TAFs through 00z Thursday Evening) Issued at 636 PM CDT Wed Apr 24 2019 IFR or LIFR ceilings are expected at KUIN and the St. Louis area terminals through Thursday morning. IFR or low MVFR ceilings are also expected at KCOU. MVFR visibilites will drop to LIFR at KUIN and KCOU late tonight and early on Thursday morning. Conditions will improve to VFR or high MVFR on Thursday afternoon as winds turn out of the northwest allowing drier air to move into the region. SPECIFICS FOR KSTL: IFR or LIFR ceilings are expected to remain over the terminal through Thursday morning. Some light showers will be possible terminal through tonight. Conditions will improve to VFR or high MVFR on Thursday afternoon as winds turn out of the northwest allowing drier air to move into the region. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
751 PM EDT Wed Apr 24 2019 .SHORT TERM...(This evening through Thursday) Issued at 423 PM EDT WED APR 24 2019 Water vapor imagery and RAP analysis show zonal flow across the northern CONUS/southern Canada. A rather vigorous shortwave was just n of MN over northern Ontario. Low-level jet of 35-45kt ahead of this trof has supported a few -shra/sprinkles over ne MN. Some of these sprinkles have moved into western Upper MI recently. Mid-level clouds that have been spreading over western Upper MI today have held temps down a bit from what was expected, but still most locations over the w half of Upper MI have topped out in the 60s this aftn. For the next few hrs, expect a few sprinkles moving from western Upper MI into central Upper MI. Otherwise, aformentioned shortwave will continue to shift e across northern Ontario tonight. Associated cold front currently moving across northern MN should be over central Upper MI at 12z Thu. Satellite imagery currently shows some convective looking mid-level clouds vcnty of the front, but no shra yet. Many of the models develop isold/sct shra along the front over ne MN during the next few hrs, and with a little weak instability lingering aloft tonight, a few -shra may accompany the front as it moves into the area during the night. Will be a mild night ahead of the front. Low to mid 40s should be the rule for much of the fcst area. Front will slow down Thu in response to a vigorous shortwave tracking across s central Canada. This wave will reach nw MN Thu evening. Expect increasing post frontal lake breeze component off Lake Superior during the day to help push the front s out over Lake MI. Until it does so, there may be a few shra vcnty of the front. Some of the high res guidance, NAM in particular, generate convection over Menominee County in the aftn due to build up of several hundred j/kg of mucape with the convergence from the front and lake breeze development off the Bay providing the forcing. Have some doubts on that much instability, but will be something to monitor Thu aftn. Behind the front, another surge of drier air will follow. Leaned fcst toward the drier GFS idea and incorporated some of the dry air mix down potential to lower dwpts, especially over the nw half Thu aftn. Not much cooling follows the front for Thu. With temps rising back into the 60s, min RH may tumble to 20-25pct over the interior nw half. With wind off Lake Superior, it will be cooler along the lake, especially e of Marquette. Temps there may briefly rise in the morning before the front passes, then fall back thru the 40s. .LONG TERM...(Thursday night through Wednesday) Issued at 343 PM EDT WED APR 24 2019 Although regionally the pattern will remain active through the next 7 days, no widespread significant precipitation events are expected through next Tuesday, which is good news for area rivers that will be able to recede through the weekend. Generally near to below normal temperatures are expected into early next week as well. Thursday night, a shortwave will dive in from the NW, bringing some cloudiness and perhaps a shower or two over the north and east, but thankfully the airmass will be too dry for much in the way of rain. Friday, mainly just some diurnal cumulus and cooler temperatures back in the 45-53 degree range. CAA will continue into the weekend with Sat highs struggling to rise above the lower 40s. Medium/long range models have flip-flopped again with the system moving in this weekend, bringing the main precip shield back south into WI. However the 84 hr NAM remains further north, so still cannot rule out some precip across the southern CWA, especially near Menominee. If it does clip our area, main ptype appears to be snow per model soundings, and a jog back to the north could mean several inches mainly on grassy surfaces at MNM. GFS soundings are very dry during this time along the WI border, perhaps due to persistent northerly flow, with NAM soundings saturated through the column. Reality will likely end up somewhere in between. Brief, relatively weak ridging will allow for some sunshine Sunday that will bring temperatures back near 50 inland west. Weak shortwave activity on Monday may lead to a few light showers mainly over the west. Flow should be more zonal on Tuesday with quiet weather likely to continue, however a more robust shortwave will ride up the eastern side of a persistent Western CONUS trough into the middle of the week that is expected to bring our next chance for appreciable rainfall. Track, timing, and intensity are still in question at this time, with the ECMWF being the most bullish with rainfall potential over the UP Wednesday into Thursday. Although the deterministic GFS brings the bulk of the precipitation well to our southeast, GEFS ensemble mean precip indicates a tendency back towards our area. Continued chance POPs during this period, only increased slightly from the blend. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 741 PM EDT WED APR 24 2019 With low-levels remaining relatively dry, VFR conditions will prevail at KIWD/KMCX/KSAW through the forecast period. A cold front moving across the area tonight into early Thursday may produce some isold light showers. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 423 PM EDT WED APR 24 2019 Ahead of an approaching cold front tonight, expect s to se winds generally in the 10-20kt range, strongest over the e half where gusts may reach 20-25kt for a time. Behind the front, westerly winds should be under 20kt on Thu. In the wake of another passing cold front Thu night, w to nw winds of 10-20kt are expected on Fri over western Lake Superior and 20-30kt over the e half. Not out of the question for winds gusts to reach gale force over the e. High pres ridge building into the northern Great Lakes should support winds falling to mostly under 20kt for the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...KCW AVIATION...JLB MARINE...Rolfson