Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/22/18

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
609 PM MDT Fri Sep 21 2018 .AVIATION... 00Z TAF CYCLE Rich low level moisture is in place across central and eastern areas thanks to persistent easterly flow behind a back door cold front that arrived early this morning. This will allow low clouds with MVFR and IFR conditions to linger into the early evening across the east central and southeast plains. Areas of low clouds with IFR conditions will probably also develop along the east slopes of the central mountain chain early this evening, and perhaps even at KSAF. However, models depict drier air settling into the far eastern plains by late evening, and some downslope flow developing along the east slopes of the central mountain chain by then. This should cause areas of low clouds to decrease in coverage and become patchier across the plains through the late night hours. Fair weather is expected Saturday. 44 && .PREV DISCUSSION...227 PM MDT Fri Sep 21 2018... .SYNOPSIS... Cool and breezy conditions with a few showers across southeastern New Mexico will continue through tonight then dissipate after sunrise Saturday. Patchy fog is possible Saturday morning along the east slopes of the central mountain chain. High pressure will build over the state over the weekend and bring delightful weather with mild and sunny afternoons and cool nights. Temperatures will warm closer to normal Monday with increasing westerly winds. A back door cold front is on target to move through the eastern half of New Mexico Tuesday as a trough of low pressure passes to our north. Showers and storms may return to the area Tuesday night and Wednesday along with cooler temperatures. && .DISCUSSION... The back door cold front that moved through eastern NM this morning has brought cool and breezy conditions to the plains. Low cigs in its wake are slowly dissipating but will likely redevelop along the east slopes tonight. The latest RAP visibility product shows fog in a few areas along the east slopes of the central mt chain. An area of low cigs are also possible around the Cont Dvd where low level convergence exists behind the cold front. Temperatures tonight will be a few degrees warmer than last night with weaker inversions. Saturday through Monday will offer delightful September weather as dry upper level high pressure crests over the area. Winds will be relatively light with temperatures modifying close to or slightly above normal through Monday. Overnight low temps will be cooler with efficient radiational cooling leading to strong inversions. Patchy fog cannot be ruled out within mountain valleys and the eastern plains on any night as soils are rather moist across the area. Tuesday will feature another back door cold front across the eastern plains as an upper level trough shifts east through the central Rockies. This front is shown with very good model agreement to advance west into the Rio Grande Valley late Tuesday and set the stage for showers and storms along and east of the central mt chain through Wednesday. Guyer && .FIRE WEATHER... High pressure aloft will continue building in from the west tonight and Saturday. Temperatures will trend up to slightly above average over the weekend and into early next week underneath the above mentioned upper high. A relatively strong backdoor cold front will drop into eastern New Mexico Tuesday, pushing west of the central mountain chain Tuesday night. Models are trending wetter with this feature, developing showers and storms along and near the front as it moves through eastern and central portions of the state Wednesday. A drier backdoor front is forecast to slide in from the northeast Thursday night. Widespread fair to poor ventilation rates are forecast over northern and central New Mexico Saturday. Improving rates are forecast for Sunday through Tuesday with a downtrend in rates Wednesday. 33 && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service La Crosse WI
1100 PM CDT Fri Sep 21 2018 .SHORT TERM...(This evening through Saturday) Issued at 245 PM CDT Fri Sep 21 2018 The upper trough over the northern Great Lakes will continue to progress eastward this evening/overnight with high pressure building in from the west. Winds will rapidly decouple/subside by sunset as the high builds in with skies clearing from the north and west by early evening. With light winds/clear skies overnight, temps should cool into the 30s to low 40s over the region. The favored cool spots across central and north-central Wisconsin look most susceptible to frost with lows expected into the low to mid 30s. Will issue a Frost Advisory for these areas for early Saturday. In addition, some river valley fog may form early with light flow under the surface high. Seasonably cool weather will be the rule for the weekend with dry conditions as the surface high migrates eastward across the Great Lakes. Highs on Saturday will generally be in the 60s on Saturday with some modest recovery into the low 70s in spots on Sunday as southerly flow develops ahead of low pressure developing across the high plains. .LONG TERM...(Saturday night through Friday) Issued at 245 PM CDT Fri Sep 21 2018 A relatively cool period is expected for much of the coming work week. Temps on Monday will rise back into the 70s ahead of an upper trough and associated cold front that is forecast to slide through Monday night. Instability looks fairly unimpressive, but chances for showers and storms will increase late Monday into Monday night with the front. Behind the front, low-level cold advection/breezy northwest winds are expected Tuesday with some lingering clouds or possibly a few showers under cyclonic flow aloft with the passing upper trough. Surface high pressure briefly is expected to build over the area under zonal flow aloft ahead of another upper trough and associated cold front dropping out of the northern plains by around Thursday. This will bring rain chances back to the region. Highs will generally be in the 60s following the cold front Monday night, with perhaps even cooler air invading following the late week cold front && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1100 PM CDT Fri Sep 21 2018 Cigs/vsby/WX: clouds have shifted south this evening - and expect mostly skc/sct VFR conditions through the weekend. The one caveat to this is the potential for valley fog and/or bkn low stratus at KLSE Sat morning. Winds off the deck blowing +10 kts, but progged via RAP Bufkit soundings to lighten and deepen overnight. More suggestive of a sct-bkn003 potential at KLSE with any fog holding over the river channel. Will keep BCFG sct003 for now. River valley fog will continue to be monitored Sun/Mon mornings with high pressure in the vicinity. Again, low level winds look to be a tad too high to allow for dense fog at KLSE - at least for now. Winds: light vrb overnight. Should become southerly early Sat, holding around or just below 10 kts through the afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Frost Advisory from midnight tonight to 8 AM CDT Saturday for WIZ017-029-034-042. MN...None. IA...None. && $$ SHORT TERM...JM LONG TERM...JM AVIATION....Rieck
Area Forecast Discussion
National Weather Service Columbia SC
1025 PM EDT Fri Sep 21 2018 .SYNOPSIS... A large dome of high pressure aloft will ensure fair weather through at least Saturday. The high will shift to our east Sunday through early next week, while a slow moving front approaches and stalls, and moisture increases from a low-level flow off the Atlantic. Another front will move into the region mid to late week but may stall. These factors will lead to increasing precipitation chances next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Surface pressure ridge will remain centered along the New England coast with ridging extending into the forecast area. Moisture remains shallow and a strong mid-level cap is in place which will keep conditions dry overnight. Low temperatures will range from the mid 60s to around 70 degrees under mainly clear skies. Most of the models are indicating at least patchy late night fog given shallow but ample low-level moisture combined with dry air aloft. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Large dome of high pressure aloft will remain overhead Saturday, while considerably dry air aloft remains in place. This will ensure fair weather and continued above normal temps Saturday. Gradual increases in lo-level moisture may provide some late night/early morning fog/stratus potential. By Sunday, upper high to shift to our east. A front will move into the Mid Atlantic States then back door down towards our region Sunday. Current indications are that the weak wedge will remain just to our north Sunday but may be able to progress south into our northern forecast area (FA) Sunday night. Slight increases in moisture may provide slight chance POPs Sunday mainly to our north near the front and near the coast. && .LONG TERM /MONDAY THROUGH FRIDAY/... Limited confidence Monday on how far south the wedge will get. GFS more aggressive with it than other guidance. Will expect weak wedge to be in or near our northern FA early Monday with some expectation of gradual erosion during the day Monday, though some uncertainty exists. Upper high to remain to our east while upper troughiness develops into the central CONUS. Upper disturbance and area of low pressure offshore to move towards the SE Coast in clockwise flow around the upper high. Latest guidance indicates the system weakening as it approaches the coast. A series of fronts expected to approach our region mid to late week. Gradual moistening of the atmosphere expected to lead to increasing POPs. Some questions as to whether the frontal boundaries will stall near our region or be able to move through late in the forecast period. Went with model consensus. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected during the 24-hour TAF period outside of early morning fog or stratus. Dry high pressure will continue to dominate. There may be enough low-level moisture combined with nocturnal cooling to help cause stratus and fog during the early morning hours. Little boundary layer wind favored fog over stratus. Low-level moisture was highest in the east and south sections affecting the AGS, DNL, and OGB terminals. We followed the GFS LAMP and forecasted a period of IFR fog at these terminals. Forecasted a period of MVFR farther northwest at the CAE and CUB terminals. Confidence is low because there was spread in the guidance with the HRRR and crossover temperatures indicating mainly VFR conditions. Heating and mixing should dissipate any fog beginning around 13z. Expect variable but mainly easterly wind less than 10 knots during the daytime hours. EXTENDED AVIATION OUTLOOK...An onshore flow should bring low-level moisture with an increased chance of late night and early morning stratus and fog. There will be a chance of mainly afternoon and evening showers and thunderstorms. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Grand Junction CO
516 PM MDT Fri Sep 21 2018 .SHORT TERM...(Tonight through Saturday night) Issued at 348 PM MDT Fri Sep 21 2018 Nice and quiet across eastern Utah and western Colorado this afternoon as dry southwest flow remains overhead. A few cumulus clouds have developed across the San Juan Mountains over the last hour or so with an isolated storm or two possible later on this evening. Looking at webcam imagery across southeast Utah, patchy smoke can be seen filtering into the region from the Riggs and Lonely fires burning in south-central Utah. The experimental HRRR-smoke shows smoke continuing in this area through this evening before dispersing to the northeast. Areas of smoke were also added in and around the eastern Uintas as the HRRR shows smoke from the Pole Creek Fire moving in from the west late tonight. The upper level gradient will tighten on Saturday as a broad Pacific trough digs into the northwestern CONUS. Mostly sunny skies will support mixing during the afternoon hours resulting in breezy conditions, especially up in northwest Colorado. However, confidence on the duration and intensity of wind gusts remains low to moderate, so no changes were made to the Fire Weather Watch on Saturday. More on that in the Fire Weather discussion below. Otherwise, weather conditions on Saturday will be very similar to what was experienced today with slightly warmer temperatures and isolated storms down south. High level clouds will begin to increase Sunday night as an upper level jet approaches the region. .LONG TERM...(Sunday through Friday) Issued at 348 PM MDT Fri Sep 21 2018 As referenced in the Short Term discussion, an upper level jet associated with the Pacific trough will dive into the Great Basin early Sunday. As the jet moves through the forecast area throughout the day, a surface cold front will also push across the region. Isolated showers and thunderstorms will develop over the higher terrain across the northern tier of the area Sunday afternoon before spreading to the central and southern mountains Sunday night. Activity will persist into Monday afternoon before drier air quickly filters into the region from the west-northwest. Breezy conditions will accompany the passage of the jet and the cold front, potentially leading to critical fire weather conditions across far northwest Colorado Sunday afternoon. Mostly sunny skies will return to the region on Tuesday, though daytime heating will lead to isolated storms firing over the San Juan Mountains Tuesday afternoon. Daytime highs will have cooled to right around seasonal normals on Tuesday, though readings will rebound back to several degrees above normal by Friday as high pressure rebuilds over the southwestern CONUS. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 515 PM MDT Fri Sep 21 2018 A few gusty winds up to 30kts are being reported at a few TAF sites this afternoon. Namely, KRIL AND KEGE while others are seeing gusts up to 20kts. These winds will die down over the next few hours giving way to light winds as clear skies continue. More of the same tomorrow. && .FIRE WEATHER... Issued at 348 PM MDT Fri Sep 21 2018 Expect southwest winds to increase over northwest Colorado this weekend ahead of an approaching Pacific trough. Vegetation remains very dry across the region so gusty southwest winds combined with above normal temperatures and low relative humidity could result in critical fire weather conditions. Confidence is increasing for Sunday afternoon when the ~60 knot upper level jet moves overhead. As for Saturday, while plenty of sunshine will allow for some mixing during the afternoon hours, Red Flag criteria looks to be more borderline. Therefore, the Fire Weather Watches for both Saturday and Sunday remain in effect. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Fire Weather Watch from Saturday afternoon through Saturday evening for COZ200. Fire Weather Watch from Sunday afternoon through Sunday evening for COZ200. UT...None. && $$ SHORT TERM...MMS/KS LONG TERM...MMS/KS AVIATION...TGR FIRE WEATHER...TGJT
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1028 PM CDT Fri Sep 21 2018 .DISCUSSION... Storms have been firing this evening over NW counties where some immediate flooding concern exists. Have already issued one advisory and will continue to monitor there. Expect those cells to be locked in that area for awhile yet then gradually shift toward the SE based on latest HRRR runs. Some cells have had some rotation leading to right movement relative to and opposing to mean flow...leading to forther slowing of storms and higher local rain amounts. As per previous discussion wet period remains in place for several days yet. Although most of the focus of convection is farther north...ingredients are right for locally heavy downpours with precipitable water values close to 2.5 through will need to be wary of any training echoes...which might lead to flash flooding. Most locations more likely to have more of a localized street or poor drainage flooding threat. 18 && .PREV DISCUSSION... /ISSUED 736 PM CDT Fri Sep 21 2018/ AVIATION... Storms over most of the region have diminished with just some lingering light stratiform rain. Closer to the coast a narrow band of showers/thunderstorms moving through the GLS/EFD area with gusty winds...more storms lining up offshore south of Galveston. More concerning in the short term is the area of local convergence around CLL-11R-AUS corridor with the development of thunderstorms. Have altered the CLL terminal to carry a TEMPO for a few hours there with TSRA but some of the short term guidance supporting a threat extending as late as 05z. Some patchy light fog possible after midnight though the mid/upper cloud deck should help hold temperatures up tonight. After 06z except showers to develop in the moist axis over the coastal waters aimed in general toward the GLS bay area. Expect scattered showers to stream into the GLS area extending up to around HOU area with instability on the increase toward morning will probably see more thunderstorms mixed and the area of showers/thunderstorms intruding further north into the IAH/CXO area. By mid morning easily reached convective temperature of 83 should lead to development of more storms inland and a lessening over the Gulf waters. Area terminals will be plagued with showers or thunderstorms in the vicinity for hours throughout the day. Another concern will be the development of a line of storms late afternoon or evening along the approaching Pacific cold front/thunderstorm enhanced by outflow boundaries moving through the Hill Country and nearing the western CWA. The mesoscale interactions could make for a wet period but it could be just west of the Metro hubs or it may just reach them. Far from settled yet. 45 PREV DISCUSSION... /ISSUED 357 PM CDT Fri Sep 21 2018/ DISCUSSION... Another day today of showers and thunderstorms, and this is a pattern that does not look to change any time soon as an early fall front sags towards Southeast Texas. The worst flooding concerns will be well to our north and northwest, though the northwestern edge of our area may be close enough to the heavier rain that we`ll have to keep a close eye on trends and mesoscale features. Look for daily bouts of showers and storms carry through next week, with another potential front late next week. NEAR TERM [Through Tonight]... For now, radar shows storms are moving quickly enough that, despite some briefly torrential rainfall, there are not yet any flood concerns. However, if any type of backbuilding or training sets up, particularly in places like eastern Harris County where a round of heavy rain has already fallen. While water vapor imagery shows a subtle vort max roughly over the Houston area, expectations are that towards evening, that will move off to the east, and leave an area of relative subsidence between this vort max and the vorticity associated with a trough over Central Texas. That should cause convection to dampen or even end completely for a brief time. However, any respite will be short-lived, and towards dawn, convective development looks to begin again - particularly in the vicinity of Galveston Bay and its Gulf waters. SHORT TERM [Saturday Through Sunday Night]... Saturday and Sunday will again bring us further bouts of showers and storms, though the character of that rain may change subtly. Saturday should see trends begin much like recent days, with nocturnal marine convection transitioning to the coast, and then spreading inwards. However, at the same time, a boundary will be dropping into the area from the northwest. Really unsure whether it`s a true cold front, or some sort of large amalgamated cold pool boundary, but I suppose in the end it`s really unimportant precisely what it is. This boundary will serve as the increasingly dominant focus for convection from Saturday into Sunday as it droops in. Fortunately, the upper trough supporting the front to a high risk of excessive rainfall in Oklahoma and North Texas today should begin to flatten and lift to the northeast, starving the boundary of upper support as it moves southeastward. This should keep the greatest rainfall threat to the north of our area, though with ample moisture we may see localized flooding potential from briefly torrential rainfall. The operative word in that last sentence, however, is should. Any further deepening of the trough or failure to eject would combine with the slow moving boundary and very high moisture levels could create a more significant rainfall situation. For this, WPC has brought down it`s marginal risk area for excessive rainfall to the coastline, covering most of our area. LONG TERM [Monday Through Friday]... The string continues early next week, as an inverted trough moves westward across the Gulf of Mexico. Though it will weaken and dissipate as it approaches the area, it will keep the subtropical ridge from building back in and continuing rain potential. Finally, for the back half of next week, our next upper trough will move into the area and could bring us our first real taste of fall...emphasis on "could". The trend in the modeling has been for a weaker trough, and though it`s only been a subtle trend, it is enough at this time of year to feel increasingly uncertain about just how strong its associated front will be. For now, the forecast does not significantly impact temps and dewpoints for the late week, but does nudge things down a bit until onshore flow resumes. What there is more certainty on is continued good potential for rain, so PoPs still relatively high, especially given the range of this forecast. AVIATION [18Z TAF Issuance]... Scattered shower and thunderstorm activity is expanding across Southeast Texas and will continue through the afternoon. The strongest storms will have gusts up to 25-30 mph with brief heavy rainfall and frequent lightning. Will add TEMPO groups as necessary through the afternoon hours, but expect periods of showers and thunderstorms for most of today. Some guidance is more bullish and keeps the convection around until 02-03Z near the Houston Metro, but sinking air as a result of the stronger storm complex over Central Texas will likely dampen these storms closer to sunset. With extra moisture from today, cannot rule out patchy fog development in more rural areas, but a BKN/OVC cirrus deck may result in no fog development. An additional disturbance and surge of moisture tomorrow morning will move onshore from the Gulf, so have started shower development much earlier tomorrow than was seen today. Isolated thunderstorms are possible early tomorrow morning, as well. Morning showers will eventually transition to thunderstorms 16-18Z tomorrow and persist for much of the day. 22 MARINE... Light to moderate onshore winds will prevail for the next few days. Winds may briefly shift to northerly as a weak boundary progresses southward into the Gulf. The pressure gradient will gradually relax this weekend as the boundary progresses southward, at which point winds will follow a typical diurnal pattern. Otherwise, periods of showers and thunderstorms will continue through the weekend. Expect locally higher winds and waves in any storms. 22 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 75 87 72 84 72 / 40 80 60 50 30 Houston (IAH) 77 87 75 86 74 / 60 80 50 70 40 Galveston (GLS) 80 86 78 84 78 / 70 80 60 60 60 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...18
Area Forecast Discussion
National Weather Service Louisville KY
950 PM EDT Fri Sep 21 2018 .Forecast Update... Issued at 945 PM EDT Fri Sep 21 2018 Weakening showers continue to push east over east-central KY. These showers originated along the surface cold front earlier this evening. This front has been a little slower than model forecasts on its movement SE into central KY. The front is very close but still has not cleared SDF or LOU. A new rain shower recently popped up again near the Jefferson Co IN-Trimble Co KY line along this front. Overnight, the front will sag slowly south, but have upped morning low temps a degree or two in some areas north of the front. Clouds will stream NE into the lower OH Valley. The next question is precip potential. With ample moisture available, anywhere south of the front will have a chance of showers overnight. High resolution short range models do show development of some showers and perhaps a few storms over central/south-central KY after midnight. In addition, current radar shows storms developing over parts of middle and western TN, which the latest HRRR model lifts NE into south-central KY late tonight. Thus, have upped POPs some over south-central KY overnight. Scattered light rain showers may return to parts of north- central KY by morning. Issued at 550 PM EDT Fri Sep 21 2018 Radar indicates that a line of showers and thunderstorms continues to move east into east-central and south-central KY at this time. Still a few strong cells in the line with gusty winds, but trend last half hour or so has been for a slight weakening, although still very heavy rain with the strongest cores. This is along a pre- frontal trough or convergence line. The actual surface front is marked by a fine line on radar near the OH River at this time, and renewed convection that has fired on this front, even through the pre-frontal convection took a bit of the energy and instability with it. The frontal storms will sag southeast, affecting Jefferson, Oldham, and Henry in the immediate term, with scattered other cells expected over north-central KY as the front sags south across the OH River. The front will end precip chances for awhile over the northern part of the forecast area with some temporary clearing behind it until more clouds move back into the region from the west and southwest later tonight. Grids/forecast has been updated to account for latest radar trends and expected cloud and precip chances overnight and Saturday. && .Short Term...(This evening through Saturday) Issued at 310 PM EDT Fri Sep 21 2018 A closed low at the surface located at the southern tip of the Hudson Bay on the Quebec/Ontario border has a cold front extending down through the Great Lakes and the Ohio Valley. Several outflow boundaries ahead of the cold front have produced lines of showers and storms that are affecting S Indiana and Central Kentucky that appear to be causing a stabilizing effect on the atmosphere prior to actual frontal passage this evening, thus reducing the severity of storm chances associated with frontal passage. A current line of showers and storms extends from north-central KY southwestward to SW KY. SPC convective outlook has S Indiana and central KY is a marginal threat of severe weather. With sufficient instability (CAPE around 2000 J/kg) and deep layer shear at 30kts, some of these storms do have potential to be severe. Main threat would be damaging winds associated with storms (DCAPE between 800 and 1000 J/kg). Another possible hazard would be localized flooding issues as precipitable water values edge close to 2 inches ahead of the front. But these storms are moving pretty quickly and training should not be an issue. A break in clouds between the outflow line of storms and the actual cold front could allow enough heating to bolster the line of showers into storms associated with the cold front as it moves into central KY this evening. But as the sun begins to set, loss of diurnal heating should quell any further development and convection should begin to diminish. Overnight into tomorrow morning expect a low layer of stratus to form. Precipitable water values remain high and with another shortwave pulse moving through the boundary to our south, expect chances of showers to begin overnight and through tomorrow midday. A noticeable drop in temperatures should be evident as the front passes this evening. Highs today rest around the 90 degree mark. Lows Saturday morning will be around 60 in S Indiana gradually increasing to mid to upper 60s in southern KY. Highs tomorrow in the upper 60s in S Indiana and N KY and reaching the upper 70s in south central KY. .Long Term...(Saturday night through Friday) Issued at 250 PM EDT Fri Sep 21 2018 ...UNSETTLED AND WET SEVERAL DAYS... Behind the initial wave of short-term rains associated with the cold front, expect continued rain chances Saturday night. With a departing jet streak aloft, we should have enough lift for a band of light to moderate rains falling somewhere south of the Ohio River, even well behind the stalling frontal boundary. We may see a brief break in the rains Sunday morning as that wave lifts out, but with the front still close enough and additional waves coming, would not be surprised to see additional showers form Sunday afternoon. Models then are fairly uniform in bringing the stalled front back north as a warm front Sunday night and Monday. A moist airmass comes with that surge. We could see some low-level jet convergence aiding storm development early Monday, but otherwise support aloft is weak. Rain chances Monday night and Tuesday morning will depend in part on how far north that boundary lifts. A trailing cold front then looks to sweep across the region some time between Tuesday afternoon and Wednesday, with model guidance still spread out on timing a little. Timing more during peak instability would lead to some severe storms coming through, given stronger winds aloft on forecast soundings. GFS and Euro both hinting that this front too will stall out, whereas the GEM pushes it through far enough to pull rain chances out the rest of the week. Given the GEFS means keeping in solid rain amounts, have to have at least some rain chances in for the end of the work week. As for rainfall totals...we should have some periods with heavier rain mixed with drier patches. Rainfall totals through Wed are fairly hefty, with 2-3" along the Ohio River and upwards of 5 inches over south KY. There`s still some wiggle room here, with regard to locations and given the longer range of the forecast. Will issue a Hydrologic Outlook to discuss how area rivers can handle this rain. Temperatures generally will be below normal this forecast period for highs and near normal for lows. && .Aviation...(00Z TAF Issuance) Issued at 750 PM EDT Fri Sep 21 2018 Cold front is nearing SDF and will continue to sag southward through the evening and overnight. Showers and storms along and ahead of it have cleared HNB, SDF, and BWG, while LEX should see the threat for a few storms over the next 1-2 hours. Winds will shift to W and NW with frontal passage, then become more northerly overnight. Outside of possible reduced vsbys at LEX with showers in the next hour or two, conditions should remain VFR into the overnight period. Toward morning, MVFR cigs may develop at BWG and LEX as additional low-level moisture begins to move into the area. Models differ in the timing and amount of the next round of showers to move into central KY Saturday. TAFs reflect scattered showers (no thunder) affecting BWG and LEX during the morning with a better chance in the afternoon under a NE surface breeze and MVFR cigs and vsbys, possibly IFR cigs at times. SDF should be on the edge of the rain shield but may see some MVFR conditions later in the day. Meanwhile, HNB should remain north of the showers, with VFR conditions continuing. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update.......TWF Short Term...CG Long Term....RJS Aviation.....TWF
Please see the previous forecast discussion for details about this
weekend`s weather and the upcoming warmup next week.
&& .AVIATION...For the 22/00Z TAFs...VFR will continue for all points south and east of the Umpqua Divide, with the exception of areas in the vicinity and downwind of active fires. A cold front approaching will bring possible showers to the coast and into the Umpqua Basin later tonight, with cigs likely dropping to IFR along the coast and MVFR in the Umpqua. Periods of lower vsby are also possible in showers. && .MARINE...Updated 200 PM PDT Friday 21 September 2018...A frontal system will move through the northern waters by Saturday morning, bringing some light rain. High pressure will build offshore this weekend into early next week and a thermal trough will develop along the coast. Steep seas and gusty north winds may develop south of Cape Blanco Saturday night. Then, Sunday into Monday, expect a mix of steep to very steep seas and strong gusty north winds that could reach gale force south of Cape Blanco. In addition to the possible gales, steep to very steep waves will be possible across these areas as fresh swell mixes with the background swell and diminishing wind waves. North of Cape Blanco, small craft advisory level winds and seas are possible Sunday evening through Monday. Elevated steep seas may continue in the waters Tuesday into Wednesday due to a mix of wind seas and swell. -Schaaf/CC && .FIRE WEATHER...Updated 230 PM PDT Friday, 21 September 2018... The thermal trough will shift east over the westside valleys today and will bring warmer afternoon temperatures to most areas. West winds will increase late afternoon and evening and RHs are low enough to warrant a headline, particularly over Fire zones 285, 624 and 625, but these areas are not expected to reach critical fire weather criteria. A weak cold front could bring a few showers mainly north of Cape Blanco along the coast and from the Umpqua Divide northward and west facing slopes of the Cascades from about Crater Lake north early Saturday morning into Saturday afternoon. Models are indicating slightly higher precipitation amounts, but amounts are still expected to be less than a tenth of an inch,with the highest amounts in 617 and the northern Cascades. Confidence is higher we will be dealing with dry conditions with gusty northeast winds (another thermal trough pattern) Sunday into next Wednesday with moderate to poor overnight recoveries possible starting Sunday night. The models are now showing 925 mb winds higher and supportive of gusty northeast winds, and the pressure gradient is tight which also supports gusty winds. The combination of wind and moderate to poor overnight recoveries could be cause for concern for the Klondike Fire Sunday night through Wednesday morning. However, humidity recoveries are too high for a fire weather watch at this time. From yesterday`s discussion; "Climatologically, many of our most robust east winds have occurred during the last week of September and the first week of October, so this certainly bears some watching." -Sven && .PREV DISCUSSION... /Issued 254 PM PDT Fri Sep 21 2018/ DISCUSSION...High clouds continue to stream in from the west this afternoon on the front side of an upper level trough moving into the area. More dense cloud cover has reached Florence, and we expect a continued trend toward increasing and lowering clouds across the forecast area the remainder of today into Saturday, greatest and fastest for areas furthest northwest. Meanwhile, through these high clouds, fire activity appears to have been slow to pick up. The only discernible area of significant smoke is currently blowing generally west to east from the north side of the Klondike Fire from about Glendale south to Merlin. This is about where the HRRR Smoke Model shows where it should be. Smoke monitors across the area are not showing increases yet, but those in Grants Pass and Medford are expected to this evening. Further south, the predicted increase in smoke from the Delta Fire in the Mount Shasta area is, thus far, not happening. The reason all this smoke is being mentioned is because the wind pattern this afternoon through Saturday evening is expected to be very similar to what occured last weekend, when some smoke impacts developed Friday into Saturday. We expect to get a better gage of the smoke based on what does or does not occur this morning. Thus far, the situation looks somewhat encouraging in that the fires appear less active than they were a week ago. However, we`ll see how it looks later this evening and reassess. Otherwise, the incoming trough will bring a substantial cool down to the forecast area between today and tomorrow that is likely to last through Monday morning. High temperatures are expected to fall about 10 degrees over today`s for Saturday and Sunday, while lows stay about the same due to increased cloud cover. We`ll also need to keep an extra close eye on Monday morning, when drier air and clearing combine. While not a certainty, it is possible that some of the colder spots in the west side valleys such as in the Illinois, Applegate, and Rogue valleys could experience their first frost of the month/latter half of the growing season Monday morning. Incidentally, the Autumnal Equinox occurs tomorrow/Saturday at 654 PM PDT. Regarding rainfall with the incoming front, while model guidance has generally trended slower and not as wet as previous model runs indicated, we do still anticipate some light rainfall along and near the coast and in the Umpqua Basin late this evening through Saturday. While isolated locations in northern Coos and northern Douglas counties could experience a tenth of an inch or more of precipitation, most areas that get rainfall will see less than a tenth of an inch. Also of note is that a number of the high resolution models indicate an area of showers getting going along/near the Siskiyous Saturday evening. Therefore, a possibility of evening showers has been added to the forecast for that area. Sunday through Tuesday dry and drying east winds are expected to cause temperatures to warm to 10 to as much as 20 degrees above normal for Tuesday through Thursday. A Rex Block expected to be present in the eastern Pacific next week does not bode well for precipitation for our forecast area, so expect that fire season will continue. -Lutz && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. Pacific Coastal Waters...Small Craft Advisory from 11 PM Saturday to 5 PM PDT Sunday for PZZ356-376. $$
Area Forecast Discussion
National Weather Service Paducah KY
823 PM CDT Fri Sep 21 2018 .UPDATE... Issued at 824 PM CDT Fri Sep 21 2018 Made some mid-evening update for the remainder of tonight to more closely reflect the surge of light precipitation overnight from the southwest ahead of the mid-level low currently straddling the central KS/MO border at 00z Saturday (7 pm CDT). Secondary line of sprinkles and/or light showers will develop northeastward from southeast Missouri into southern Illinois for the remainder of the evening, eventually spreading back through west Kentucky by daybreak Saturday. KPAH VAD Wind Profile shows a more distinct elevated frontal boundary near 5kft AGL, while the KHPX and KVWX wind profiles are near 5-7kft AGL. There is a little more gradient and vertical mixing developing over south Central Illinois and southwest Indiana early this evening. This combined with the ageostrophic response to the approaching low will provide for a slight increase in northerly winds overnight. Made a slight adjustment (1-2 degrees) on temperatures overnight to reflect precipitation, cloud cover, temperature and dewpoint advection behind the front overnight. The potential for over-running/isentropic lift will persist overnight from southeast Missouri to points northeast. The 12z ECMWF, combined with the HRRR, ESRL HRRR, and RAP high resolution guidance appear to have a good handle on the return of moisture over the WFO PAH forecast area. Reduced the coverage of any thunderstorm mention to the evening hours and mainly across southern sections closer to the frontal boundary, cutting through the southeast part of the west Kentucky Pennyrile region around 00z. Added a mention of sprinkles from mid-deck cloud cover overnight and reduced thunderstorm coverage to the southern Pennyrile area closer to the surface cold front. UPDATE Issued at 643 PM CDT Fri Sep 21 2018 Updated aviation discussion for 00Z TAFs. && .SHORT TERM...(Tonight through Sunday night) Issued at 323 PM CDT Fri Sep 21 2018 The outflow from this morning`s convection has passed through the entire region as of 20Z, and the cold front is difficult to find in the wind field. It appears to be near the Wabash River to near Dexter Missouri and is finally getting a push with gusty northwest winds over southeast Illinois. The outflow boundary thoroughly messed up the wind fields, but many places were able to warm up to near 90 degrees with sporadic sunshine. With little forcing aloft and little convergence on the front, convection will be very limited if not nonexistent for the remainder of the afternoon. We will continue to monitor radar/satellite trends, but severe weather is no longer expected. This evening will be mostly dry, but a few light showers or periods of sprinkles will be possible. The 12Z models are not in the greatest agreement with the onset of the over-running showers/storms overnight and Saturday. The GFS is wetter and farther north and east, while the NAM is slower, drier and farther south. The ECMWF seems to be more like the GFS. Cannot rule out some thunder mainly over west Kentucky and the Bootheel late tonight and Saturday, but this will be elevated and weak, so no severe concerns here. We will maintain likely to categorical PoPs mainly over the southern half of the region through Saturday. There should be a lull in the precipitation over most of the region Saturday night through Sunday, but far southern and southeastern portions of the region may not be so fortunate. The consensus of 12Z guidance pushes the warm front back into west Kentucky overnight Sunday night, so we will see PoPs back into likely territory. Will also re-introduce thunder in the southeast at this time. As for rainfall, far southern portions of the area could see 2 inches through the weekend, but this tapers quickly to under a tenth of an inch north of I-64. Without the more persistent convective rates, any flooding issues should be very minor. However, this may just be setting the stage for issues as we head into next week. .LONG TERM...(Monday through Friday) Issued at 323 PM CDT Fri Sep 21 2018 Confidence in the extended forecast is not that great. The ECMWF and GFS agree that the warm front will push north of the area during the day Monday putting our entire area in the warm sector. They are not in such agreement in the timing of the cold front, or the general character of the larger-scale upper trough. The ECMWF has been the most consistent in pushing the cold front through Tuesday night and then drying us out for the most part for Wednesday through Friday, while the GFS has a more positively tilted trough and is slower to move the front into our area and then kind hangs it up over our area. This will lead to the potential for heavy rainfall and flooding over the area. The faster ECMWF would definitely lead to a quicker cessation of the rain and less of a heavy rain/flooding threat. && .AVIATION... Issued at 643 PM CDT Fri Sep 21 2018 VFR conditions are forecast through Saturday. Upper level energy streaming along and north of a frontal boundary forecast to stall south of the region will bring the potential for showers into at least southern portions of the region later tonight into Saturday. Carried prevailing showers at KCGI and KPAH, with a VCSH mention at KEVV and KOWB. This may result in a reduction to MVFR ceilings and visibilities at locations near the Arkansas and Tennessee borders, but the TAF sites should largely remain VFR. North to northeast winds around 10 knots will prevail. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...Smith SHORT TERM...DRS LONG TERM...PS/DRS AVIATION...RJP
Area Forecast Discussion
National Weather Service Shreveport LA
953 PM CDT Fri Sep 21 2018 .UPDATE... Flash Flood Watch area and orientation looks good through the overnight hours as it`s our northwest zones which have received a bulk of the precipitation thus far. Checking area Mesonet sites across McCurtain County, Oklahoma, nearly the entire county has seen rainfall in excess of 2 inches with Idabel having seen 3.33 inches and points north and west of Battiest, Oklahoma have seen upwards of 5 inches since midnight last night. Likewise, much of the adjanct counties across Southwest Arkansas in the watch area has seen 1-3 inches so far as well. Looking at the lastest radar mosaic, much of our region is currently in a lull when it comes to precipitation coverage but a giant slug of precipitation, closer to the orientation of the upper level trough, is setting up just to our west attm and slowly moving north and east. Expect this to continue to move eastward overnight with the area likely to see the greatest potential for flooding to be in the Flash Flood Watch area, thus no Watch extendtion in coverage will be made with this forecast. Did increase rain chances overnight pretty much areawide and also increased pops through much of our region through the day Saturday as well based on the latest data coming in from the HRRR and 00z NAM. Many areas currently near or at their overnight lows as of 9 pm due to earlier rainfall and they should pretty much stay there overnight. Update already sent...13. && .PREV DISCUSSION... /issued 543 PM CDT Fri Sep 21 2018/ AVIATION... Terminal forecast is a big mess through the next 24 hours with a stagnant upper level trough to our west, continuing to provide the necessary lift for scattered to numerous convection through the period. Current thinking is that present convection will begin to dissipate somewhat in coverage after the 04z hour across all but our northern and western most terminal locations which would include the TYR/GGG/TXK. These sites are closer to the above mentioned lift and could see on and off convection through the overnight hours. Further to the east, short term progs support a downward trend in convection later this evening with convection not developing and/or moving into these terminals until beyond Sat/14z or so. For the western terminals, have gone with prevailing VCTS with TEMPO groups for restrictions associated with TSRA this evening with additional TEMPO groups needed from midnight through the predawn hours for continued convection. Went ahead and prevailed TSRA at the TYR/GGG/TXK/ELD and LFK terminals during the morning hours on Sat with prevailing TSRA at the SHV/MLU terminals during the afternoon hours. Once this convection sets in on Saturday, ceilings will be slow to improve, if at all so for now, have prevailed MVFR ceilings through much of the day on Sat. Look for mostly variable winds through the next 24 hours with speeds near 6kts or so except for variable winds much stronger and gusty near thunderstorms. 13 PREV DISCUSSION... /issued 353 PM CDT Fri Sep 21 2018/ SHORT TERM.../Tonight through Saturday Night/ Enhanced rain chances expected through Saturday across much of the region with widespread persistent rainfall targeted mainly across the interstate 30 corridor along a weak and slow moving frontal boundary. With precipitable water values around 2 inches areawide, locally heavy rainfall will be possible. As upper-level trough shifts east across Texas this evening, coverage and intensity of precipitation is forecast to increase. With latest RFC flash flood guidance of 3 to 4 inches per hour, and the potential for 24 hour QPF values approaching 5 inches across these areas, a flash flood watch will be necessary. Rainfall axis to shift south across the heart of the ArkLaTex on Saturday allowing for likely pops areawide with residual precipitation continuing through Saturday night. Temperatures tonight to average in the lower 70s. Highs on Saturday to climb into mid to upper 70s north of I-20 and mid to upper 80s across deep East Texas and north Louisiana. Cool surface high pressure building behind the front to bring lows on Saturday night into the mid 60s to lower 70s areawide. /05/ LONG TERM.../Sunday through Friday Night/ A wet and unsettled weather pattern will continue across the Four State Region through much of the next work week. On Sunday a shear axis will exist over the region in between an upper ridge, that extends along the southeast coast of the US into the Northeast Gulf of Mexico, and a trough over the Northwest Rocky Mountain States. At the surface, a surface low will develop along a stationary front located just north of the Interstate 20 corridor. Showers and thunderstorms will continue to develop along the boundary through the beginning of the work week as the sfc low and boundary slowly move southeast across the region before washing out. By mid week, rain chances remain in the forecast as another upper trough will dive towards the region bringing another cold front into the forecast area and also becoming nearly stationary over parts of East Texas and Central Louisiana before washing out on Thursday. By Friday, another cold front will make its way towards the region, bringing additional showers and thunderstorms through the first part of the weekend. The prolong period of rainfall this week, will provide much needed relief to ongoing drought conditions across the region and cooler temperatures as high temperatues are expected to remain in the mid to upper 80s. /20/ && .PRELIMINARY POINT TEMPS/POPS... SHV 74 86 71 83 / 50 80 70 50 MLU 73 90 71 85 / 40 70 70 50 DEQ 71 77 66 78 / 100 100 70 50 TXK 72 78 66 77 / 80 90 70 50 ELD 73 83 68 79 / 70 80 70 50 TYR 73 82 70 82 / 80 80 70 50 GGG 74 84 70 82 / 70 80 70 50 LFK 74 87 73 85 / 40 80 60 50 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Flash Flood Watch through Saturday afternoon for ARZ050-051- 059>061. LA...None. OK...Flash Flood Watch through Saturday afternoon for OKZ077. TX...Flash Flood Watch through Saturday afternoon for TXZ096-097- 108>111. && $$ 13/99