Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/04/17

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
700 PM CDT Tue Oct 3 2017 .AVIATION... For the 00Z TAFs, a low confidence forecast with respect to all elements. Amendments possible. Surface cold front will meander around the region tonight and Wednesday morning before slowly dissipating. Expect low cigs in the IFR and/or MVFR categories to prevail through late Wednesday afternoon along with areas of fog. In addition, occasional rain showers and a few thunderstorms are expected to impact the terminal sites tonight and Wednesday. Andrade && .PREV DISCUSSION... /Issued 423 PM CDT Tue Oct 3 2017/ DISCUSSION... Cold front made a slow southward progression today before coming to a halt near the Canadian River valley. Low- to mid-level moisture remains plentiful even on the north side of the front, with 850 mb dewpoints as analyzed by the RAP still remaining in the 11 to 15 degree Celsius range behind the 850 mb front. Have maintained healthy pops tonight as moist low-level upslope flow is augmented by occasional disturbances in southwest flow aloft. Frontal boundary expected to lift slowly north on Wednesday, with warm advection and isentropic lift warranting continued high pops through Wednesday night. Chances for rain diminish a bit Thursday and more so Thursday night as low-level winds become more southwesterly. Friday and Friday night bring increasing chances for rain as final shortwave trof passes, driving a cold front through the area. Much drier post-frontal air brings dry weather back to the Panhandles for the weekend. Next cold front Sunday night and Monday brings a taste of autumn with high temperatures 10 to 15 degrees below climo and overnight lows falling well into the 40s Monday night. Cockrell && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$
Area Forecast Discussion
National Weather Service La Crosse WI
530 PM CDT Tue Oct 3 2017 .SHORT TERM...(This afternoon through Wednesday) Issued at 102 PM CDT Tue Oct 3 2017 Expecting more showers and storms to pop up going into late this afternoon/evening as the cold front pushes into the area. Latest CAMs (Convection Allowing Models) showing the cold front and associated showers/storms pushing southeast out of the area by 10 pm or so. Have tailored pops to reflect this timing. Latest RAP pushes MUCAPE this afternon into the 1000-1500J/kg range but this may be a bit overdone given the amount of cloud over us inhibiting full heating potential. 0-3km bulk shear in the 30-35kt range. Will keep a close on on the potential for a few stronger storms with small hail and gusty winds given the shear and cape if clouds do develop holes which would allow more heating/instability. Clearing expected then from the northwest to southeast after midnight as the front clears the area and high pressure builds in from the Northern Plains. Look for overnight lows in the middle 40s to the middle 50s. A cooler/drier/mostly sunny day on tap for Wednesday as that area of high pressure drifts overhead. Plan on seasonable temperatures as highs top off in the 60s...with perhaps a few lower 70s across far southwest WI/far northeast IA. .LONG TERM...(Wednesday night through Monday) Issued at 102 PM CDT Tue Oct 3 2017 An active/wet period setting up for Thursday through Saturday as a couple areas of low pressure roll out of the Central Plains into the Upper Mississippi River Valley region. The first area of low pressure looks to impact the area Thursday into Thursday night with incoming warm front and increasing moisture transport. Instability/CAPE looks fairly limited with NAM indicating 0-3km MUCAPE of 500-750J/kg. So, looks like mainly showers with embedded thunder during this period. could be some pockets of heavier rainfall as well with PWs pushing to around 1.5 inches south of I-90. Frontal boundary looking like it will hang out across southern WI/northern IL/northern IA Thursday night for continued shower and storm chances mainly south of I-90. A stronger area of low pressure ejects northeast out of the Central Plains and through southern WI later Friday night into Saturday morning for another round of shower/storms and possibly pockets of heavier rainfall as PW values push up into the 1.5-1.8 inch range mainly across the south and east. Mean areal average rainfall from Thursday through Saturday looks to range from 1/4 to 1.5 inches, with pockets of heavier amounts. This should put a dent in the abnormally dry/drought conditions in place across our area. Sunday looks mainly dry as another cold front swings through but then rain chances return Sunday night into Monday from central WI into northeast IA as southwest flow aloft brings another wave of low pressure through IL. Otherwise, temperatures are expected to remain right around seasonal normals. && .AVIATION...(For the 00Z TAFS through Wednesday evening) Issued at 530 PM CDT Tue Oct 3 2017 Cigs/WX/VSBY: cold front sweeping through the region early this evening - already passed KRST and should do so at KLSE before 00z. Scattered -shra/ts along and post the front. Brief ifr/MVFR vsby reduction possible with any of the heavier rainfall. Some MVFR cigs also post the front for 1-3 hours. By mid evening the skies clear under the influence of high pressure, and should hold that way through Wed evening. Wind: generally light west/northwest, picking up bit by Wed afternoon but holding from that direction. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...Rieck
Area Forecast Discussion
National Weather Service Billings MT
711 PM MDT Tue Oct 3 2017 .UPDATE... Water vapor imagery shows our region being under a col between a departing low in ND and a cutting off low over the Great Basin. Shower activity has ended as surface high pressure has settled in, and main forecast concerns are cold temps and fog potential. There is an area of upslope cloud along the eastern slopes of our western mountains, and this could have an impact on both temps and fog, but indications are that this will erode over time. Most if not all of our cwa will see temps fall below freezing tonight. Records at Billings (27), Miles City (27) and Sheridan (25) will be challenged, again depending on cloud cover. Weakening winds and clearing skies, along with dew points in the mid 20s to lower 30s, point toward the potential for fog. Have expanded patchy fog coverage a bit (including at Billings), but latest HRRR runs have actually trended toward less overall coverage. Would be surprised if there wasn`t some localized fog in river valleys by sunrise. JKL && .SHORT TERM...valid for Wed and Thu... Upper low over NW North Dakota is slowly shifting northeastward and filling. Its influence is decreasing as isentropic lift and upper divergence shift with it. High resolution models have handled precipitation the best so far today, and following their lead will keep a slight chance of rain/snow showers over Fallon and nearby areas through the early evening. We should otherwise see decreasing clouds tonight. Our main weather message for tonight is a first "hard freeze" for many locations at the lower elevations (28 degrees or lower for a few hours). We do not issue highlights for this, but will message through social media and our web page. For Wednesday, after a chilly start we should see some warming over todays readings. However, another cut off upper low over Nevada will slowly lift northward and bring our western mountain zones under a divergent flow with increasing mid level moisture. SO some rain or snow showers are possible by late afternoon. Some of the lift and moisture moves across the plains as well tomorrow night. The air associated with this system is from the south so we do not anticipate much if any snow overnight, but perhaps a mix after midnight. Main precipitation band lifts north of us by Thursday morning but proximity of upper low over our CWA may lead to rain and snow showers in the mountains and nearby areas through Thursday night. Any accumulations should be of on the meager side and of little impact. BT .LONG TERM...valid for Fri...Sat...Sun...Mon...Tue... Models are overall in good agreement through the upcoming weekend. An upper low and trough will move east into the central high plains with brief ridging building across our forecast area Friday. This will be short-lived as a strong upper low and trough drop southeast out of Canada Friday night into Saturday. This will also bring a strong cold front across the forecast area during the day Saturday. Pressure gradients will be tight ahead of the front resulting in gusty southwest winds especially for the Big Timber to Livingston areas. Very little if any precipitation is expected along the front. However, by Sunday shower chances return as the upper low and trough will be situated over the state. Temperatures will be normal Friday and Saturday with readings in the lower to middle 60s. Readings will be much cooler Sunday with 50s likely, and especially Monday and Tuesday when highs in the 40s will be possible. Hooley && .AVIATION... Skies will gradually clear from west to east during the late evening and overnight hours with mostly clear skies expected after 06z. Expect the gusty northwest winds to subside shortly after sunset. Some patchy fog and reduced visibilities are possible for areas along and north of a KLVM-KBIL-4BQ line after 06z through 12z Wednesday. Otherwise, expect VFR conditions into Wednesday. Hooley/Reimer && .PRELIMINARY POINT TEMP/POPS... Wed Thu Fri Sat Sun Mon Tue ----------------------------------------------------------- BIL 027/054 035/057 038/065 045/064 040/053 034/047 031/046 00/U 31/B 11/U 01/B 23/W 21/B 11/B LVM 025/050 032/053 035/062 043/062 036/048 030/045 025/043 02/W 32/W 21/B 01/N 24/W 31/B 11/B HDN 025/059 035/058 038/066 042/066 039/055 035/049 031/048 00/U 21/U 11/U 01/B 23/W 21/B 10/B MLS 027/056 037/057 038/063 043/065 039/055 034/047 030/045 00/U 31/B 01/U 01/N 11/B 11/B 10/B 4BQ 026/058 038/057 038/062 042/066 039/053 034/047 031/044 00/U 21/B 11/B 01/U 22/W 11/B 10/B BHK 026/056 038/056 037/061 042/064 038/053 034/046 030/042 10/U 21/B 01/B 01/N 11/B 01/B 00/B SHR 025/058 035/057 035/062 038/067 037/052 032/047 029/044 01/U 11/U 11/B 00/U 33/W 31/B 10/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Houston/Galveston TX
933 PM CDT Tue Oct 3 2017 .DISCUSSION... At 01z, sfc high pressure was located over eastern MS and another surface high was over SW KS. There is still a strong onshore flow and showers continue to develop over the western Gulf and move inland. 00z soundings show PW values between 2.20 and 2.45 inches so the air mass still looks plenty moist. Drier air is progged to move southwest late tonight and moisture levels will begin to drop. At 300 mb, upper level ridging is becoming centered over south Texas. At 850 mb, high pressure was noted over NC and this feature was inching westward. 850 moisture still looks robust with 850 dew points around 16 C. Will maintain the 30-40 PoPs currently in the grids but did raise min temps a degree or two in places as confidence is low that the drier air well off to the east will make it here by morning. Wet ground may lead to some light fog by morning but left that out of the grids at this time due to mixing from winds and extensive cloud cover. 43 && .CLIMATE... City of Houston established a new annual rainfall record with 74.18 inches of rain so far in 2017. It`s hard to believe that an annual record was broken with almost a full 3 months to go in the year, but it is what it is. The previous record rainfall for a year was 72.86 inches set back in 1900. 43 .PREV DISCUSSION... /ISSUED 639 PM CDT Tue Oct 3 2017/ AVIATION... Some patchy areas of IFR/MVFR will affect KIAH and the nearby aviation sites through 02/03Z. Otherwise, isolated to scattered showers will linger through at least mid evening. There is a general downward trend in the models regarding rain chances; although, for KIAH, KHOU, and KSGR the NAM12 has another better chance of rain between about 08Z and 11Z. If the cloud cover clears out enough later this evening or overnight tonight could see at least patchy fog to form. The more likely scenario is for a mid or high level VFR deck to persist overhead which will keep fog formation chances low. The models and guidance both suggest an MVFR deck will be possible late tonight into early morning Wednesday. Any low decks or fog that do form should lift to VFR by around 15Z. 40 PREV DISCUSSION... /ISSUED 344 PM CDT Tue Oct 3 2017/ DISCUSSION... Scattered showers and thunderstorms seen on radar imagery this afternoon, expected to hang around through much of the early evening hours. Locally heavy rainfall and higher rain rates will be possible in isolated stronger storms. Should see coverage begin to shift into the western portions of our forecast area closer to sunset. GOES-16 precipitable water imagery still shows the best moisture over the western half of SE TX and further west of the forecast area. Short term guidance such as the HRRR and RAP13 continue widely scattered to isolated precip mainly over the western reaches into the early morning hours. Should continue to see partly to mostly cloudy skies overhead through late Wednesday and into early Thursday, until upper level ridging begins to build in over the region. This area of high pressure will slide westward by late Friday, which should allow for more of a summer like pattern to return to the forecast Saturday. Saturday through Monday kept PoPs (20%) mainly concentrated along the coast, associated with the typical daytime heating and sea breeze pattern. Temperatures through the remainder of the week should remain 4 to 7 degrees above normal for this time of year. Early next week, global models are still indicating a frontal passage pushing through the region. Based on the most recent runs of the GFS and ECMWF, there is still lack in agreement on timing of the front, as well as the amount of precip expected out ahead of the boundary. GFS and the Canadian model solutions are a tad slower than the ECMWF. GFS places more rainfall out ahead of the frontal boundary itself, moving into SE TX late Tuesday into early Wednesday. On the other hand, the ECMWF brings less precip out ahead of the front into the region Monday afternoon into early Tuesday. Currently trending the forecast more towards the GFS and Canadian solutions, in terms of both timing and PoPs. With this system a week out, there is still plenty of time for the models to get a better handle on both strength and timing. Regardless, should see cooler temperatures behind the front along with drier conditions. Hathaway TROPICS... We will continue to monitor an area of low pressure currently located in the southwestern Carribean Sea near Panama, expected to move towards the NW Caribbean. The National Hurricane Center have increase the formation chance up to 40% over the next 48 hours and 60% over the next five days, of the system becoming a tropical cyclone. Overpeck/Hathaway MARINE... The pressure gradient will remain tight across the northern Gulf of Mexico tonight through much of Wednesday with higher pressures along the northern Gulf. This will maintain a long fetch of moderate to strong easterly winds. Seas should build to near 9 feet in offshore waters Wednesday into Wednesday night. These building seas have started piling water up along the upper Texas coast. Current water levels are running about 1.5 to 2 feet above normal tide table values. These levels will be capable of producing minor coastal flooding around times of high tide along the more susceptible roads along the Bolivar Peninsula, Blue Water Highway and Beach Drive in Surfside. As confirmed by Galveston Beach Patrol this morning, rip currents will also be a high risk. The Beach Hazards Statement in place discusses the high tides, elevated surf and rip currents. The statement will remain in effect through at least Wednesday, possibly into Thursday. Winds and seas will gradually decrease Thursday into Friday with low winds and seas for the weekend. Overpeck && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 74 87 69 88 67 / 50 10 0 10 10 Houston (IAH) 74 87 70 88 68 / 50 10 10 10 10 Galveston (GLS) 80 87 78 88 77 / 50 30 30 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Wednesday evening for the following zones: Galveston Bay...Matagorda Bay. Small Craft Advisory until 7 PM CDT Wednesday for the following zones: Coastal waters from Freeport to the Matagorda Ship Channel out 20 NM...Coastal waters from High Island to Freeport out 20 NM...Waters from Freeport to the Matagorda Ship Channel from 20 to 60 NM...Waters from High Island to Freeport from 20 to 60 NM. && $$ Discussion...43
Area Forecast Discussion
National Weather Service Indianapolis IN
1136 PM EDT Tue Oct 3 2017 .UPDATE... Aviation section updated && .SYNOPSIS... Issued at 337 PM EDT Tue Oct 3 2017 The forecast period will be much more active than the last few weeks as a series of low pressure systems passes through the forecast area over the next seven days. The first is progged to start affecting central Indiana this evening with its associated cold front eventually stalling over the Lower Midwest through the end of the week. At that point, the second low pressure system will finally push that front farther north early in the weekend, but showers and thunderstorms will remain in the forecast through Saturday as the second low moves through. After brief ridging and dry conditions on Saturday night and Sunday morning, yet another system will pass through Ontario. Its associated cold front will bring additional chances for showers and isolated thunderstorms late in the extended period. && .NEAR TERM /Overnight/... Issued at 951 PM EDT Tue Oct 3 2017 Surface analysis late this evening shows strong high pressure over the east coast. A weak cold front was found across Wisconsin and Iowa. Water vapor imagery shows a stream of moisture stretching from Texas across Illinois to the Great Lakes...edging into NW Indiana. Cold cold front and associated moisture stream are expected to sag southeast across Indiana overnight. As this stream of moisture cover should increase along with chances for rain. HRRR shows possible -shra development overnight. Time height sections show good saturation within the lower and mid levels...but minimal forcing. The 310K GFS Isentropic surface show weak upglide amid a moist surface. Thus keeping some pops in place overnight appears reasonable given the good moisture but weak forcing...However any amounts that may occur will be quite light. Given the expected clouds and ongoing weak warm air advection...will trend lows at or above forecast builder blend. && .SHORT TERM /Tomorrow through Friday/... Issued at 337 PM EDT Tue Oct 3 2017 Showers and thunderstorms will remain in the forecast through tomorrow across most of the forecast area as a cold front continues its passage. Confidence remains medium to high in best chances being over the northwestern third of the forecast area through the morning hours. After that, forcing will begin to wane a bit as the front moves farther south, but upper forcing will keep chance pops (north) and slight chance pops (central) in the forecast until that front shifts back north and stalls over the area on Thursday. Again, highest chances for showers and thunderstorms will be across the northern half of the forecast area along the frontal boundary through the end of the forecast period. Meanwhile, temperatures through the period will remain above normal with highs ranging from the mid 70s to low 80s and overnight lows in the 60s, stuck with latest model blend initialization. && .LONG TERM /Friday night through Tuesday/... Issued at 256 PM EDT Tue Oct 3 2017 A seemingly wet extended timeframe with numerous chances for precipitation. The period begins friday night with an approaching upper wave and associated low and cold front from the central plains. Mid/long-range models are in decent agreement as to the timing of the impacts into the area. Thunder remains a possibility with the showers along and ahead of the front pushing into the area Saturday afternoon/evening. Model solutions then begin to diverge and confidence begins to wane in how the next upper trough will eject/evolve from the upper plains. ECMWF is more progressive and more amplified with its solution than the GFS...leading to earlier and more precipitation early next week. Stuck close to model initialization confidence not high in which solution may be the correct one. Above normal temps look to continue into the extended timeframe...except toward the end when a return to normal arrives by Tuesday...maybe later if the GFS is correct. && .AVIATION /Discussion for the 040600Z IND Taf update/... Issued at 1136 PM EDT Tue Oct 3 2017 VFR Conditions are expected this TAF Period. Water Vapor continues to shows a stream of moisture from TX to Illinois and Wisconsin...with some cloud streaming east into west Central Indiana. This stream of moisture is expected to push slowly east and become more east-west oriented as a weak cool front sags out of the upper midwest. Any CIGS as these feature approach should be VFR. Models continue to suggest a lack of organized forcing and only a stray shower or storm will be expected. Confidence too low to provide specific timing for this event. Thus used a VCSH window for when best moisture appears present. Best window for TSRA looks like during daytime heating hours on Wednesday afternoon...however forecast soundings appear to show limited instability. Thus confidence for any thunderstorms is low. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...TDUD NEAR TERM...Puma SHORT TERM...TDUD LONG TERM....MRD AVIATION...JP
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1002 PM EDT Tue Oct 3 2017 .SYNOPSIS... High pressure will dominate the weather through most of this week. Low pressure and unsettled weather regime is possible for late this weekend into early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 955 PM Tuesday...A clear sky over most of the forecast area has allowed temps to cool back into the 60s most spots. Min temps from low to mid 50s inland to low- mid 60s coast still look on track. An area of clouds off the coast are just now moving onto the Outer Banks. We are seeing a few sprinkles with these just offshore of Cape Hatteras. Returns farther south and west north and northeast of New Bern are associated with a clear sky and likely are chaff. Will continue a slow increase in clouds along the immediate coastline with a slight chance of a light shower here. Best chances will be across the Outer Banks but even here the increase clouds is expected to be more pronounced than any rain shower threat. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... As of 300 PM Tuesday...Subtle wind shift to E-SE around 900 MB will continue, allowing additional influx of offshore moisture resulting in increased SCU and scattered shower threat along coast with slight chance POPs inland to Hwy 17. Max temps mid to upper 70s. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... As of 4 PM Tue...High pressure will remain the dominant feature over region through the first half of the weekend continuing the period of mainly dry weather. The high will shift offshore late weekend into early next week with some unsettled weather and a return to warm and humid conditions. Wednesday night through Saturday...With the high still ridging into E NC from offshore and light NE to E winds, conditions will be near climo with mild days and cool nights. Have fcsted overnight lows with cooler MET/ECS MOS vals due to good radiational cooling and low TD`s. There will be some patchy fog each early morning as T-TD spreads will be near 0 each night/morning. Highs will steadily warm each day as low lvl thicknesses rise into the 1420M range by Sat, with readings in the mid 80s interior to low 80s beaches. Overnight lows will start out cool initially with mid 50s interior to low 60s coast, then moderate to low 60s inland to mid/upr 60s coast by the weekend. Sunday through Tuesday...There is still model dispute on evolution of shortwave energy and potential tropical development that will lift NE out of the GOM late in the weekend into early next week. 03/12Z CMC/GFS indicate a slower and more westward propagation of this activity across the TN valley, while latest ECMWF is more in line with its previous 03/00Z ensemble mean, which is quite unsettled across E NC with tracking shortwave and tropical disturbance through the Carolinas from the Gulf coast. Have therefore continued just chc pops, highest inland, for the Sunday/Monday period. Will have to continue watching trends as a heavy rain/flooding threat may develop if ECMWF advertised 2+ inch PWATS verify for Sunday and Monday. A return to to warm and humid summery-type regime with highs well into the 80s and muggy overnight lows between 70-75 late weekend through early next week. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Short Term /through 18Z Wednesday/... As of 755 PM Tuesday...VFR will through 06Z. Late tonight there is better potential for fog and low clouds producing sub VFR conditions after midnight as the low level flow becomes easterly and moistens a shallow near ground layer. Latest RUC continues to indicate period of IFR to LIFR likely 08Z- 12Z for most sites with lowest VSBYs and longest duration at KPGV and KISO. Soundings look a little less certain for KEWN and based on past observations, only show 3SM and MVFR here. Conditions improving to VFR quickly after 14Z Wednesday with scattered SCU developing rest of morning. Long Term /Wednesday night through Sunday/... As of 4 PM Tue...Pred VFR conditions expected through the period, though could see early morning sub-VFR fog and stratus develop each late night and early morning through the period. && .MARINE... Short Term /through Wednesday/... As of 955 PM Tuesday...Northeast winds continue mainly 15 to 20 kt with a few gusts into the lower 20s. With seas still running 5 feet to around 6 outer waters, continued SCA through tomorrow for marginal conditions on the waters. Pressure gradient over the waters will weaken later tonight and Wednesday, allowing winds to diminish to 10-15 KT and seas to subside below 6 ft by Wednesday night. Long Term /Wednesday night through Sunday/... As of 4 PM Tue...Strong high pressure will gradually slide offshore mid to late week. Generally easterly flow 5-10 kt expected through Friday. Winds veer SE for Sat and Sun though remain generally in the 5-10 kt range, with some higher 15 kt gusts for the coastal waters. Seas will be 2-4 ft northern waters to 3-5 ft southern and central waters through the period. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement from 8 AM EDT Wednesday through Wednesday evening for NCZ095-103-104. MARINE...Small Craft Advisory until 8 PM EDT Wednesday for AMZ152-154- 156-158. && $$ SYNOPSIS...JBM NEAR TERM...JBM/EH SHORT TERM...JBM LONG TERM...TL AVIATION...JBM/EH/TL MARINE...JBM/EH/TL
Area Forecast Discussion
National Weather Service Paducah KY
442 PM CDT Tue Oct 3 2017 .UPDATE... Issued at 439 PM CDT Tue Oct 3 2017 Updated Aviation discussion for 00Z TAF Issuance. && .SHORT TERM...(Tonight through Thursday night) Issued at 305 PM CDT Tue Oct 3 2017 Main issue in the near term remains the potential for widely scattered showers and isolated thunderstorms through midday Wednesday, especially across portions of southeast Missouri and southern Illinois. An upper level ridge situated from the eastern Great Lakes to the Tennessee Valley and Gulf of Mexico will be suppressed into the Southern Plains by Thursday. Meanwhile, surface high pressure will remain anchored off the Atlantic Coast. Southerly flow on the back side of this high will maintain warmer than normal temperatures through the period. Widely scattered showers impacted portions of southeast Missouri and southern Illinois today. Expect the potential for another round or two of widely scattered showers and isolated thunderstorms tonight into midday Wednesday as weak energy ripples through the moist southwesterly flow on the west side of the upper level high. Much of the period from Wednesday afternoon through Thursday night should remain dry as the active weather focuses across the Plains into the Upper Midwest along a frontal zone. Some models suggest the potential for showers may infringe upon our northern tier of counties in southern Illinois and southwest Indiana late Thursday night, so we maintained a slight chance there. Temperatures through the period will largely be influenced by the amount of sky cover, with highs averaging in the lower 80s and lows in the lower 60s. Areas that hang on to more cloud cover may experience highs in the upper 70s and lows in the mid 60s, while locations with more clearing see highs in the mid 80s and lows in the upper 50s. .LONG TERM...(Friday through Tuesday) Issued at 305 PM CDT Tue Oct 3 2017 Forecast confidence is fairly high through Saturday and then decreases Sunday through Tuesday. There has been reasonable agreement in the GFS and ECMWF for the last few cycles of the remaining portion of the current western U.S. trough pivoting out of the central and northern Plains into the Upper Midwest Friday through Saturday. This will bring a decaying cold front eastward into our region Saturday. The models have been consistently indicating that the associated frontal band of convection will dissipate as it attempts to move through our region. Decent chance PoPs are warranted over southeast Missouri, southern Illinois and southwest Indiana, with only small chances over much of west Kentucky. The front will be losing its focus over our region and will not pack much of a punch as far as temperatures are concerned either. Clouds will hold temperatures down a few degrees from Friday, but it will still be well above normal. We will remain in southwest flow aloft behind this initial system, and the primary surface boundary will re-establish itself to our northwest. Current indications are that most of the area will be dry and continued warm on Sunday. One fly in the ointment for late Sunday into Monday is the potential for a tropical system, as yet not developed, to lift northward into the Tennessee Valley, potential spreading some rainfall into west Kentucky. The GFS and ECMWF each have a system of some strength, but the ECMWF is a bit farther east and slower than the GFS. We will have to keep a wary eye to the south through the end of the week, as it seems most landfalling tropical systems like to visit the MS/OH/TN valley region. Heading into Monday and Tuesday, the 12Z GFS initially has an elongated upper trough from the northern Rockies east northeast into northern Ontario. The troughing will solidify into a closed low near International Falls by 00Z Wednesday. The associated cold front moves through our region Tuesday with a decent chance of convection, but it should be fairly dry Monday and Monday night. The heat would continue across the region Monday and then the cool/near normal air would start to move in Tuesday. Unfortunately, the 00Z ECMWF is much more amplified with the upper trough, and pushes it and the cold front through our region Monday and Monday night. The result of the models` lack of agreement is a steady dose of chance PoPs for all or a portion of the area from Sunday through Tuesday. Instability when it develops will be meager, so any thunderstorms will be on the weaker side, with a very localized heavy downpour and sporadic lightning the primary concerns. && .AVIATION... Issued at 439 PM CDT Tue Oct 3 2017 Rap, Nam, and Hrrr short res modeling keeps pcpn west of terminals after 00Z. Will monitor for vicinity mention necessity, however, early in period. Otherwise time/height cross sections suggest we lose the lower VFR deck and go scattered to broken mid and high decks overnight. The lower VFR bases will reappear with diurnal fueling tmrw, with the best chance for ceilings during the late pm hours at KEVV and KOWB. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday) Issued at 250 PM CDT Tue Oct 3 2017 WV satellite imagery and 12Z observed obs suggest upper level forcing and jet energy remain largely north of the forecast area into the Upper Plains region. Lower level front is draped from southeastern NE into northeastern KS back into central KS. Weak convergence is finally leading to moderate to heavy drizzle over portions of the area mainly from Falls City, NE back to the northwest of Manhattan, KS. This is all associated with the low level frontal lift through about the 925mb level. Expectation this afternoon is for drizzle to slowly develop into showers generally north of I-70 and along the Hwy 15 corridor. VIS imagery suggests some clearing has taken place generally southeast of Topeka, KS. So, destabilization with plentiful moisture in place could allow for a few showers to develop into thunderstorms with around 25-30kts of effective shear in place. Lightning will likely be the main hazard. Forecast confidence has been low with overall set up but some short-term guidance does seem to be catching on with the HRRR suggesting afternoon and early evening storms developing with post-frontal showers developing overnight into the early morning behind the surface boundary. ARW and NMM models also have generally come into similar agreement. Weak and broad isentropic lift therefore is the likely factor into the morning. Could keep showers going long enough to drop anywhere from .25-.75 inches of precipitation over portions of the forecast area. Expecting some possible reduced cloud cover and visibility with patchy post frontal fog developing as well generally after the 5Z time frame. Temp gradient remains in place from northwest to southeast over the area this afternoon and evening following with the frontal progression. Highs this afternoon top int the mid 60s northwestern portion of the area and low 80s over the southeastern portions of the area. Lows will bottom in the mid 50s to mid 60s again from northwest to southeast. .LONG TERM...(Wednesday night through Tuesday) Issued at 250 PM CDT Tue Oct 3 2017 On Wednesday night a mid level shortwave will lift out over the northern plains, which will cause the surface warm front to lift northward. Within the warm sector deep isentropic lift is expected to increase overnight and continue through Thursday evening. Each model is depicting several rounds rainfall during this time frame. There is no obvious focus for additional lift, but with southwest flow aloft a subtle shortwave could not be ruled out. There will also making it difficult to pin down the exact timing and locations of the rainfall. Model soundings are indicating that pwats approach 2 inches and warm cloud depths around 13 kft therefore heavy rainfall rates will be possible. On Friday the main trough exits the Rockies and pushes a cold front through the area. Large scale lift associated with this trough coupled with frontogenesis along the frontal zone and ample moisture should set the stage for one last round of rainfall. The deep layer shear will become parallel to the front, which supports the possibility for more heavy rainfall. One main question is the amount of instability will exist in the warm sector given the chances for cloud cover and precipitation prior to the front arrival. Quick to follow will be a deeper longwave trough to drop out of western Canada. A much stronger surface high builds into the region brining more seasonable temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 632 PM CDT Tue Oct 3 2017 Main question is duration and timing of limiting ceilings and confidence in any particular category persisting is low. Cold front just passed TOP and will move through FOE shortly. Primarily MVFR cigs follow though some variation in obs noted. Most guidance seems too high for the most part and have stayed with MVFR prevailing, to IFR after 09Z as boundary layer saturates and front stalls over southern KS. Will suggest some improvements after 15Z. Kept VCSH with limitations in any showers likely minimal. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Drake LONG TERM...Sanders AVIATION...65
Area Forecast Discussion
National Weather Service Tucson AZ
350 PM MST Tue Oct 3 2017 .SYNOPSIS...Expect isolated to scattered showers and thunderstorms east of Tucson late tonight into Thursday evening. Dry conditions will then prevail Friday into next Tuesday. Unseasonably warm daytime temperatures will prevail into this weekend, then high temperatures will cool closer to seasonal normals by the middle of next week. && .DISCUSSION...A broad positively tilted upper trough continues over the western CONUS this afternoon, low pressure centered over northern California. Meanwhile, a highly amplified upper ridge was over the eastern CONUS. Moisture is expected to increase especially across eastern sections of this forecast area by daybreak Wednesday. The 03/12Z Univ of AZ WRF-NAM and WRF-GFS and to some extent the 03/21Z HRRR were similar with depicting a few showers to occur across the White Mountains late tonight or toward sunrise Wednesday. Expect dry conditions area-wide this evening followed by isolated showers and thunderstorms across the White Mountains late tonight. The 03/12Z NAM/GFS/ECMWF/CMC remained consistent versus their respective previous solutions with depicting high pressure aloft to expand westward over the southern CONUS Plains Wednesday. Meanwhile, generally southwesterly flow aloft across this forecast area continues Wednesday as the northern California low is ejected into southern Idaho. Enough moisture is progged by the various solutions to support isolated to scattered showers and thunderstorms east of Tucson Wednesday into Thursday. The favored periods for any showers/ tstms to occur are the afternoon/evening hours. A slight chance of showers/tstms continues mainly near the New Mexico state line Thursday night. Deeper moisture is progged to be shunted well east southeast Arizona Friday as a broad upper ridge becomes positioned well south of the area, and a ridge axis amplifies along the West Coast. The inherited PoPs were reduced to just single digits Friday based on these solutions. Thus, precip-free conditions area-wide Friday followed by clear skies this weekend and likely through at least Monday. Thereafter, the 03/12Z GFS depicted a strong tropical system to approach the southwest Baja California coast around the middle of next week. Only one other GFS ensemble member depicted this system, and a quick glance at the 03/18Z GFS was similar to the ECMWF and other GFS ensembles with not having this system near that area. Thus, continued dry conditions next Tuesday under clear skies or mostly clear skies. Expect unseasonably warm daytime temperatures into this weekend followed by daytime temperatures lowering closer to seasonal normals around next Tuesday. && .AVIATION...Valid thru 05/00Z. Isolated -TSRA/-SHRA may occur across the White Mountains northeast of KSAD late tonight. Expect isolated to scattered -TSRA/-SHRA Wednesday generally east of a KSAD-KFHU line. Otherwise, clear skies or a few clouds above 20k ft AGL west of KTUS. KTUS vicinity eastward to the New Mexico state line, few to scattered clouds around 8k-12k ft AGL tonight, then few to broke clouds around 6k-10k ft AGL Wednesday. Gusty ely/sely surface wind to 20 kts at times east of KTUS. Surface wind variable in direction mainly less than 12 kts elsewhere through the period. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...A few showers and thunderstorms may occur late tonight across the White Mountains, then isolated to scattered showers and thunderstorms are expected east of Tucson Wednesday into Thursday. A slight chance of showers and thunderstorms exists across the White Mountains Thursday night, then dry conditions return area- wide Friday into next Tuesday. 20-foot winds will generally be terrain driven less than 15 mph into early next week. However, occasional afternoon gusts to 25 mph will occur. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Francis Visit us on Facebook...Twitter...YouTube...and at