Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/13/17

Area Forecast Discussion
National Weather Service La Crosse WI
633 PM CDT Thu Oct 12 2017 .SHORT TERM...(This evening through Friday) Issued at 238 PM CDT Thu Oct 12 2017 Afternoon upper air analysis showed a ridge axis moving through lower Michigan with surface analysis showing a surface trough and cold front extending north to south across the Dakotas. Low clouds remained in the area throughout the day, but continue to slowly decay from from west to east from central Minnesota into north- central Missouri. May see a brief break in the clouds by late Thursday afternoon/early evening, but additional clouds will quickly move in/develop as the cold front approaches the area from the west. RAP BUFKIT soundings have consistently shown saturating low levels after midnight, especially east of the Mississippi River, coupled with decent negative omega and some isentropic lift, so have added drizzle mention for these areas. For Friday, 12Z guidance shows the surface cold front moving into the northwest part of the forecast area by Friday morning, with frontogenesis increasing across the southern part of the forecast area during the afternoon. The best moisture transport does not reach the area until Friday evening, so have delayed the highest PoPs a bit, but rain still appears likely for much of the southern half of the forecast area by late Friday afternoon. Any instability looks to remain to the south during this time period, so have left out thunder mention. .LONG TERM...(Friday night through Thursday) Issued at 238 PM CDT Thu Oct 12 2017 Wave of low pressure rides up along the baroclinic boundary laid up across eastern IA into northern IL Friday night into Saturday morning. Increasing moisture transport/isentropic lift over this frontal boundary will produce more showers and a few thunderstorms, mainly across far northeast IA/southwest WI. Will continue to keep a close eye on Saturday afternoon/evening as our far southeastern forecast area will be on the cusp of being in the warm sector. Right now, looks like better CAPE stays just to our southeast. However, if we can get a bit deeper into the warm sector/better CAPE, we will have more than plenty Bulk Shear and impressive hodographs for a severe storm threat. Will maintain mention of a few stronger storms in the Hazardous Weather Outlook. Another aspect to consider will be heavy rain threat as precipitable water values creep up into the 1.5-2 inch range. Attention then turns to strong/deepening low pressure coming through the area later Saturday night into Sunday. Most models have central pressure dropping 15-20mb in 12 hr (Sun 00-12z) as the low lifts from northeast IA into eastern Lake MI...impressive! Models drive a dry slot into the area as the low pulls into northeast WI/southern Upper MI. At the same time, expecting winds to pick up significantly from the west as the low rapidly deepens. Could see winds sustained in the 20-30 mph range with some gusts over 40 mph through Sunday morning, then tapering through the afternoon as the low pulls into eastern Ontario. Cooler air also filters in on these gusty winds with highs only in the upper 40s to the middle 50s. Clear/cold conditions set up for Sunday night/Monday morning as high pressure settles in across the region. Lows will be in the 30s and looks like it will produce frost for the majority of the area. Looks like quiet conditions then through Thursday as a ridge of high pressure builds over the central CONUS. Temperatures are expected to be at or a couple degrees above seasonal normals. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 633 PM CDT Thu Oct 12 2017 A tricky cloud/ceiling forecast through the overnight hours. Some clearing made its way into the RST area briefly late this afternoon, though lower clouds are again increasing from the south at this very moment and should result in a return to MVFR ceilings by 01Z at the latest. LSE looks to remain socked in with MVFR conditions through the night, but with a risk that ceilings will lower even farther to IFR levels around RST as moisture deepens just ahead of an approaching cold front. Seeing enough signals that will occur to justify taking them down to IFR by around 05Z, though the exact timing could slip. Similarly, should clouds by chance clear out for a little while, there could be a risk for some fog at RST as well, though confidence on that is very low. Things should improve back to VFR levels from west to east as the front passes during the morning hours, though thicker mid level clouds and some showers are expected into the afternoon and evening hours of Friday. Winds will start off southerly and then swing around northerly by later Friday, generally in the 8-15 knot range. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...CA LONG TERM...DAS AVIATION...Lawrence
Area Forecast Discussion
National Weather Service Grand Rapids MI
1012 PM EDT Thu Oct 12 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 317 PM EDT Thu Oct 12 2017 A cloudy night with pockets of light drizzle will give way to partial sunshine and milder temperatures on Friday. A frontal zone will waver over the area Friday night through Saturday night as a wave of low pressure tracks through the northern Great Lakes. Occasional rain and thunderstorms will develop in the vicinity of this front. Appreciable rain appears likely in areas north and west of Jackson, with a soaking rainfall over 2 inches possible in Central Lower Michigan. Cooler and drier weather will be in place early next week followed by moderating temperatures mid-week. && .UPDATE... Issued at 1012 PM EDT Thu Oct 12 2017 Have issued a quick update to expand the mention of patchy drizzle to include the entire area. Several ob sites have carried drizzle this evening or have had rain began/end times in the remarks indicative that some light precip has occurred. This should continue on and off overnight as RAP bufkit overviews show ocnl weak omega in the cloud layer. && .SHORT TERM...(This evening through Saturday night) Issued at 317 PM EDT Thu Oct 12 2017 A moisture-laden thermal trough at 850 mb will advect through the area tonight. Steep lapse rates within the stratus layer (between about 1 to 5 kft AGL) may encourage enough upward vertical motion to grow droplets large enough to precipitate. Low-level moisture in areas north of Holland and Grand Rapids will be augmented by flow off Lake Michigan. As such, the greater potential for precip tonight will be in west-central Lower Michigan. Dry air in layers colder than +3 C and a lack of cloud ice in the column will limit the potential for measurable precipitation, as cloud droplet size may only grow large enough for drizzle. Warmer low-level air (around 10C at 850mb) will flow into the area on Friday. With breaks in the clouds, could see highs reaching 70 near/south of Holland to Lansing. Light rain will overspread portions of the area Friday night under mid-level moisture transport and isentropic ascent. There may be just enough elevated instability for convection to reach the -10 C layer to introduce thunder chances early Saturday morning. Occasional thunderstorms will develop Saturday in the vicinity of the surface warm front, which should lift north late Saturday as southerly flow strengthens ahead of the deepening surface low. Temperatures could reach the mid 70s in southern Michigan if rain stays north. Stronger storms with locally heavy rainfall are possible Saturday evening and overnight as low level winds a couple thousand feet off the surface exceed 50 knots, MUCAPE values climb above 500 J/kg, and PW values climb to around 1.5 inches. If the surface stays warm enough overnight to maintain DCAPE where elevated convection tracks, isolated severe wind gusts would not out of the question. Rainfall potential is discussed further in the Hydrology section. .LONG TERM...(Sunday through Thursday) Issued at 317 PM EDT Thu Oct 12 2017 Strong storm system will be exiting the region Sunday...leaving significantly colder air and a strong and gusty west to northwest wind in its wake. Strong cold advection will likely result in falling temperatures Sunday afternoon...indicated in the grids. Sunday night frost could be more widespread than currently indicated if the wind can ease faster than expected. Cold air will linger Monday but warmer air will return quickly in the progressive mid level flow. Strong warm advection pattern develops later Tuesday into Wednesday...which should provide a return to unseasonably warm temperatures. Dry frontal passage on Thursday will be followed by another episode of warm and windy weather into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 755 PM EDT Thu Oct 12 2017 Widespread/persistent MVFR conditions are expected tonight into Friday morning, with ceilings of 1500-2500 ft and ocnl reductions of vsbys to 3-5 miles due to areas of drizzle/mist. Localized IFR conditions are also possible tonight and early Friday. Conditions on Friday afternoon are expected to improve to VFR, with the highest confidence and quickest arrival anticipated south and east of GRR. MKG could stay locked in with MVFR cigs Friday afternoon due to moist southwest flow off Lk MI. && .MARINE... Issued at 317 PM EDT Thu Oct 12 2017 Winds veering southwest tonight will build waves to 2-3 feet north of South Haven on Friday. Winds will shift southeast on Saturday but thunderstorms are a possibility. Gales appear increasingly likely Saturday night into Sunday. && .HYDROLOGY... Issued at 1236 PM EDT Thu Oct 12 2017 We are monitoring the potential for heavier rains and possible flooding for this weekend. A frontal system settling over the area beginning Friday night and lasting into Sunday will bring multiple periods of rain. Precipitable water values will be about as high as possible by mid-October standards with values over 1.5 inches expected. This will bring the potential to see locally heavier downpours, and some narrow bands of heavier accumulations through the period. The axis of the heaviest rain for now looks to occur generally north of a line from South Haven to Saginaw Bay. This is still subject to change depending on where exactly the front sets up. Right now, heaviest amounts looks to be over 2 inches, with some areas possibly seeing locally up to 4 inches. Thankfully this is displaced a little north from the heavier rains earlier this week. We still could be looking at some minor flooding. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...Meade SYNOPSIS...CAS SHORT TERM...CAS LONG TERM...MWS AVIATION...Meade HYDROLOGY...NJJ MARINE...CAS
Area Forecast Discussion
National Weather Service Wilmington NC
929 PM EDT Thu Oct 12 2017 .SYNOPSIS... A cold front will drop southward across the area tonight and further south before stalling in the vicinity of the Savannah River late Fri. High pressure will follow and ridge across the Carolinas from the NE States Fri thru Sunday. A much stronger cold front will approach the area from the northwest early Monday of next week, sweeping across the region and off the Carolina coasts to well offshore by early Tue. Look for a return to normal temperatures under cool high pressure for the mid to late week period of next week. && .NEAR TERM /THROUGH FRIDAY/... As of 845 PM Thursday...A broken line of convection has now developed across the ILM CWA, extending from Wilmington across Whiteville, Mullins, Effingham to Lamar. This broken line is basically the cool front that is slowly dropping southward across the FA. Looking at the soundings, the post frontal airmass remains quite shallow in the vertical with moisture trapped below the low level temp inversion. Will likely observe low stratus cloud decks later tonight thru atleast midday Fri with ceilings in the 500 ft to 1500 ft range, with lowest ceilings in a 5 hr window centered at sunrise. As the airmass after the CFP increases in the vertical, look for the low stratus overcast cloud decks to scour out by late Fri morning, leaving diurnally driven cu/sc clouds in it`s wake. Low temperatures tonight will run only 15 to 20 degrees above normal, as if it were late August. Widespread 70s for mins except upper 60s possible across the northern portions of the ILM CWA if enough cool air advects southward into the FA. Previous.................................................... As of 300 PM Thursday...several distinct boundaries are showing up on radar with the primary boundary appearing to be the front from just north of Wilmington to Florence and then it drops to the southwest of Florence. While there is little forcing aloft, the surface boundaries are producing weak meso- scale lift as convection begins to develop near them. The latest HRRR is showing the convection continuing along these boundaries through midnight before weakening. Overnight the models indicate stratus and fog developing and not breaking until the mid- day in the Carolinas. Scattered convection is expected to develop later in the day on Friday. Low temperatures will be in upper 60s to lower 70s on the southern coast tonight. With the extensive cloud cover expected on Friday high temperatures are expected in the lower 80s but if clouds break early than forecast, highs could reach the middle 80s. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...High pressure to the north will continue to extend down into the Carolinas as it shifts east through the period. At the same time a lingering trough just off the coast to the east will weaken. Northeast flow will continue between the high and trough and will bring drier air down into the area. Pcp water values will drop from around 1.5 inches Fri eve down to less than 1.25 inches on Sat. Therefore the overall column moisture will diminish, but there will be just enough shallow moisture to produce some fog close to daybreak each morning lifting through the morning and some afternoon cu Sat aftn. The model soundings show a pronounced subsidence inversion right around 12 k ft with plenty of dry air and subsidence above this layer. Included only a very slight chc of pcp mainly near the coast but overall expect fair and warm weather with temps and dewpoints lower than the past several days, but still above normal for this time of year. High temps will be in the lower 80s and lows in the mid 60s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...The chief headline this period remains the pattern change more indicative of early Autumn, arriving early next week, as the upper trough presently over the Pacific NW and northern Rockies, translates toward the US East Coast. GFS and ECMWF depictions appear in very good agreement on this scenario and certainly reckons to be more in sync with climo, and well overdue with the exceptionally warm pattern recently. As a result, a cold frontal passage is expected across NE SC and SE NC Monday, with the surface front reaching the FL peninsula by Tuesday. We may see 80s persist into Monday if the front arrives in the afternoon, but by Tuesday, maximum temperatures should run 9-13 degrees Fahrenheit cooler, with the drier and cooler pattern holding through mid-week. Beyond this , high pressure wedge pattern appears to portrayed, which should keep a near normal temperatures regime in place. Showers or a TSTM looks to be favored Monday ahead of the front, but looking at cross-sections of RH and column moisture, no guarantee because the moisture profiles are not all that wet. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/... As of 00Z...MVFR/IFR conditions this evening will have the potential to further degrade to LIFR conditions from mainly lowered ceilings with a secondary from reduced vsby from fog. This a result of a cool front slowly sinking south across the area tonight, and stalling in the vicinity of the Savannah River mouth by Fri evening. Scattered convection along and south of the ILM to FLO line initially, will sink southward along and ahead of the cool front overnight into Fri. Looking at progged soundings for various TAF sites across the area, the common sounding for all terminals is the nearly saturated air mass from the sfc to 925mb, and a subsidence inversion immediately on top, from 925mb to 800mb. This will result in low stratus ceilings for tonight, mainly after the cool front that pushes thru. A secondary result from these progged soundings is the increasing potential for fog. The majority of the various model MOS guidance does not hit the fog too hard, but concentrates on the sub 1k foot ceilings that could lower 500ft or less in a 5 hr window around sunrise Fri. Improving conditions will be met by late Fri morning and beyond. Winds will become NE around 5 kt after the CFP and should increase to around 10 kt by daytime mid-morning as high pressure begins to ridge across the forecast area from the NE states. Extended Outlook...MVFR/IFR conditions are possible during Fri and Sat mornings from reduced ceilings and/or vsby from low stratus and/or fog. Isolated to scattered MVFR/IFR produced convection is expected each day, with the best chance occurring on Monday ahead of a strong cold front. && .MARINE... NEAR TERM /THROUGH FRIDAY/... As of 900 PM Thursday...As the cold front slowly sinks southward across the local area, winds will become NNE-ENE in its wake at around 10 kt. Weak cool air advection combined with a tightening gradient from a 1030+ mb high ridges southward from it`s center across the NE States. Models may have winds too low for later tonight into Fri given the latest sfc pg tightening after the CFP along with some weak cool air advection. May have to also bump up winds hier for Fri. Significant seas will run 2 to 3 ft with 4 footers possible outer waters off Cape Fear and north of Romain respectively. the easterly swell at 9+ second periods will initially dominate the seas followed by an input from the low period NE wind driven waves. Previous.................................................... As of 300 PM Thursday...A frontal boundary is expected to shift off the coast overnight. Light south to southwest winds will continue through most of the evening and turn to the northeast after 03 UTC as the front moves off the coast. Seas will run between to 2 to 3 feet through Friday afternoon. SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Winds our of the northeast 10 kts or less will weaken further through the period and become more easterly by Sun morning as lingering trough off the coast weakens and high pressure to the northeast dominates. Seas will basically stay around 3 ft most waters through the period. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...A manageable southerly flow will prevail Sunday into early Monday, ahead of a cold front, shifting to north sometime on Monday. Expecting a lagtime, from when winds shift to north, to when a surge of wind buffets the waters. As a result we may not see `Advisory` or `Cautionary` conditions until Monday night, which may persist through Tuesday. The winds at 15-20 kt, with higher gusts will build seas to 4-5 or 4-6 feet late Monday and Tuesday, and as a result an SCA is certainly possible, especially with mild water in place, aiding mixing of robust boundary layer wind-speeds. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DCH NEAR TERM...DCH/DRH SHORT TERM...RGZ LONG TERM...MJC AVIATION...DCH
Area Forecast Discussion
National Weather Service Lincoln IL
845 PM CDT Thu Oct 12 2017 .UPDATE... Issued at 845 PM CDT Thu Oct 12 2017 The extensive low cloud deck remains over the area this evening however the evening sounding shows it to be only a few hundred feet thick at this time and satellite imagery shows a break in cloud cover from Bloomington through Paris, and a back edge from Quincy to Litchfield moving northeastward. Clearing behind the back edge should result in patchy fog forming as radiational cooling increases, and is depicted by several runs of the HRRR and other models. Main update tonight, then is to add patchy fog to southern and western portions of the forecast area. Otherwise, lows in the lower 50s and light southerly winds look good for tonight so have made no changes to temperatures and winds. && .SHORT TERM...(This evening through Friday) ISSUED AT 315 PM CDT Thu Oct 12 2017 Extensive deck of low stratus clouds continue to blanket IL/IN and into eastern IA and northeast MO at mid afternoon. These clouds trapped in a strong inversion under nearby high pressure ridge to our northeast and light winds which will likely keep skies cloudier into tonight. Could even be some patchy fog and drizzle again overnight into early Fri morning especially in east central IL where low clouds linger into Fri morning. Lows overnight in the lower 50s, with some mid 50s in east central IL. An increasing southerly flow on Friday should help break up low clouds as skies become partly sunny and temperatures to warm up to 75-80F Fri afternoon. A frontal boundary setting up from central KS ne to along the IA/IL border will initially keep chances of convection nw of CWA during the day on Friday. .LONG TERM...(Friday night through Thursday) ISSUED AT 310 PM CDT Thu Oct 12 2017 The frontal boundary will get closer to our nw counties on Fri night, bringing isolated convection to areas nw of the IL river Fri night after sunset. Then a better chance of convection spread se across areas north of I-72 overnight Fri night into Saturday, with likely pops over the IL river valley. Lows friday night in the upper 50s and lower 60s, coolest readings in eastern IL. Unseasonably warm highs in the low to mid 80s on Saturday except upper 70s over far northern CWA. Surface low pressure to eject ne from central KS into west central WI by sunset Saturday and deepen ne of the Great Lakes by sunrise Sunday. This to push the cold front se across CWA during Sat night. SPC day3 outlook has marginal risk of severe storms nw of I-55 while slight risk is just west of Knox, Fulton and Schuyler counties for Sat night. 12Z models are in better agreement with quicker exit of cold front on Sunday and have trended pops downward on Sunday morning with dry conditions over IL river valley, likely pops in southeast IL early Sunday, then dry across area by Sunday afternoon. Breezy nw winds bring in much cooler air on Sunday with highs ranging from upper 50s and lower 60s over IL river valley, and upper 60s in southeast IL. Seasonably cool lows in the lower 40s Sunday and Monday night, with a few spots reaching upper 30s north of I-72 sunday night as high pressure settles into the area early next week. A pleasant stretch of dry fall weather expected from Monday through Thu night as high pressure stays nearby just southeast of central IL. Seasonably cool highs in the lower to middle 60s Monday to warm into the upper 60s to near 70F on Tue and low to mid 70s Wed/Thu. The Climate Prediction Center (CPC) 8-14 day outlook for Oct 20-26th continues 70% chance of above normal temperatures and 40% chance of above normal precipitation for CWA. So the growing season likely continues at least two more weeks over central and southeast IL. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 638 PM CDT Thu Oct 12 2017 An extensive low cloud deck continues over central IL terminals this evening with MVFR cigs 2000-3000 ft AGL predominant. Little change is expected for several hours, but eventually a back edge to cloud cover approaching from the southwest, currently visible on satellite near the Mississippi River may arrive at KSPI-KDEC after 06Z. Otherwise, very moist conditions will continue overnight, leading to a good chance of MVFR vsby in fog developing toward morning. Southerly flow on Friday should dissipate low cloud cover through the morning, becoming SCT at 2000-4000 AGL. Winds S 3-7 kts through the period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...07 LONG TERM...07 AVIATION...37
Area Forecast Discussion...UPDATED
National Weather Service Marquette MI
905 PM EDT Thu Oct 12 2017 .SHORT TERM...(This evening through Friday) Issued at 412 PM EDT THU OCT 12 2017 WV imagery and RAP analysis indicated a mid/upper level ridge from the Gulf Coast to the ern Great Lakes and a trough over the nw CONUS resulting in sw flow from the plains to the nrn Great Lakes. At the surface, srly flow was strengthening over the upper MS valley and nrn Great Lakes between a ridge over Quebec and nrn New England and a cold front/trough from nrn Manitoba into the cntrl Dakotas. The southerly winds have also brought in enough to low level moisture to support an extensive area of low clouds over much of the region. However, there was enough dry air over the ern cwa along with additional daytime mixing for at least partial clearing over the west half of Upper Michigan. Tonight, Low level RH fcst and satellite trends suggest that clouds will fill back into the area this evening. 925-900mb winds veering from s to sw late and increasing to 30-35 knots will provide enough low level lift to sustain the low clouds and possibly produce some drizzle where srly upslope flow prevails and especially where additional moistening occurs off of Lake Michigan, such as locations from ISQ-ERY overnight. Friday, A low pressure system is expected to lift ne through Hudson Bay dragging a cold front across the Upper Michigan. Limited moisture transport and weak forcing along and ahead of the cold front may only result in a narrow band of isolated to scattered light showers or sprinkles along the frontal passage. .LONG TERM...(Friday night through Thursday) Issued at 414 PM EDT THU OCT 12 2017 Only significant impacts in the long term are due to winds and waves late Sat through late Sun. Models have generally trended farther N and strong with a shortwave and SFC low. For the most part there are two camps with the low track/strength. The GFS and NAM are very similar in deepening the low from around 1,000mb over SW WI 00Z Sun to mid 990s mb over S- central Upper MI 06Z Sun to 986mb over far eastern Lake Superior 12- 15Z Sun, then quickly E into Quebec by 18Z Sun. The CMC and ECMWF are weaker, only deepening to the mid 990s mb, and tracking farther south over northern Lake Michigan and eastern Upper MI. Still plenty of uncertainty with the exact track and strength so definitely favor the blended guidance for winds. Current "middle of the road" forecast has increasing E-NE winds Sat afternoon into early Sat night, but nothing significant over land through that time. Winds switch to N-NNW through the rest of the night while increasing up to gusts up to 35mph in land areas near central and western Lake Superior. Stronger NW winds and CAA then kick in Sun morning and early afternoon, with shorelines gusts to 45-50mph east of marquette, and gusts of 35-45mph elsewhere near Lake Superior. Winds then decrease Sun evening and night. This will lead to waves in excess of 8ft along all exposed Lake Superior shorelines in the CWA, and in excess of 12ft east of Marquette. Last season we saw beach erosion issues at 8ft and lakeshore flood issues around 14ft. However, lake levels are 6 inches higher than this time last year, so those thresholds may be lower. Of course, if the NAM/GFS solutions verify, winds will be stronger, with potential for shorelines gusts to 60mph. If the ECMWF/CMC verify, winds will be weaker. Will continue to promote the impacts in the HWO/EHWO. Only changes made to blended initialization was to pull winds to downwind shore areas late Sat through late Sun. Otherwise, no significant impacts expected and blends performed well. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 904 PM EDT THU OCT 12 2017 Advection of low-level moisture around high pressure to the east of Upper Michigan has resulted in large area of stratus over the region. MVFR conditions to IFR conditions are expected tonight through the early morning hours Friday. There could also be some light drizzle or sprinkles tonight into Friday morning. By late Friday morning into early Friday afternoon, drier air will begin to push in from the west allowing for steadily improving conditions. Most sites will likely become VFR by late morning. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 412 PM EDT THU OCT 12 2017 ...NE to N gales possible on Lake Superior Sat night into Sun afternoon... A tightening pres gradient btwn high pres to the e and low pres tracking ne to s central Canada will lead to an increase in srly winds to generally 15-25kt across much of Lk Superior through tonight. Winds will diminish slightly for Fri/Fri night as weakening cold front associated with low pres tracking to Hudson Bay moves across the Upper Lakes. New low pres will then lift ene along the frontal boundary this weekend, passing across the Great Lakes Sat night/Sun morning. Depending on the strength of the low and cold air moving in behind the low, there may be a period of NE to N gales Sat night into Sun morning over the west half of Lk Superior and then Sun morning into mid Sun afternoon for the east half of Lk Superior. Winds should be down to less than 20 kts by Mon. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Titus AVIATION...KEC MARINE...JLB
Area Forecast Discussion
National Weather Service San Francisco Bay Area
857 PM PDT Thu Oct 12 2017 .SYNOPSIS...Seasonably cool conditions will persist overnight into Friday before a warming trend develops over the weekend and into Monday. Another round of very dry conditions along with locally strong and gusty offshore winds will return Friday night into Saturday, especially over the North Bay Mountains and East Bay Hills. A cooling trend will begin next Tuesday and rain chances are forecast to develop late Wednesday into Thursday. && .DISCUSSION...As of 8:55 PM PDT Thursday...Winds have eased across our entire region and skies remain clear of clouds (although widespread smoke persists). Lack of cloud cover along with light winds will mean another cool night tonight with overnight lows forecast to be mostly in the 40s, except mid to upper 30s in the coolest interior valleys. Friday will be a day much like today with near normal temperatures and continued poor air quality in many areas due to smoke from the North Bay Fires. Surface high pressure is once again forecast to build to our north and east on Friday night and Saturday morning, setting the stage for another round of locally strong and gusty winds in the hills. Winds are expected to be strongest in hills of the North and East Bay where gusts of between 40 and 50 mph are possible across the higher terrain. Based on the latest WRF, winds will be at their strongest in the hills from about midnight Friday night through midday Saturday. In addition, renewed drying will take place across the region. These developments will create critical fire weather conditions and so a new Red Flag Warning has been issued for the North and East Bay Hills from 5 pm Friday through 11 pm Saturday (see fire weather discussion below for more details). Drier air by Saturday will result in warmer temperatures. The warming trend will then continue into Sunday as an upper ridge builds over California. High temperatures are expected to be in the 80s in most areas on Sunday, even near the coast. These warm conditions will carry over into Monday as well. A cooling trend will commence on Tuesday as the upper ridge moves off to our east and onshore flow develops. Rain is then possible late Wednesday into Thursday as a broad upper trough develops along the West Coast. Rain chances will mostly be confined to the North Bay, although the 12Z ECMWF develops light rain as far south as Monterey County. && of 4:30 PM PDT Thursday...Haze and smoke from the North Bay wildfires continue to be the challenge of the forecast. North winds aloft have brought a smoke layer into the SFO Bay Area where there have been reports of vsbys down to 4-5 miles and 3000 foot cigs. Smoke clouds and vsbys will improve a little tonight as winds decrease and the airmass stabilizes. Latest HRRR smoke model shows more smoke spreading south from the fires on Friday as winds pick up again. Vicinity of KSFO...Could see some periods of MVFR for cigs and vsbys associated with haze and smoke from the North Bay Fires through 04Z. Improving conditions expected after 04Z. West to northwest winds to 16-18 kt through 04Z. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...Generally VFR with some smoke aloft through Friday. && .FIRE WEATHER...As of 8:30 PM PDT Thursday...Winds had decreased across the fire district by late Thursday afternoon, even in the hills. Winds are forecast to remain relatively light through much of Friday. Thus, the Red Flag Warning was allowed to expire at 5 pm Thursday. However, dry offshore winds are forecast to increase again late Friday and become locally strong and gusty by Friday night and Saturday morning, especially in the North and East Bay Hills where local gusts of up to 50 mph are likely. In addition, relative humidity recoveries are expected to be very poor in the hills on Friday night, and RH values are forecast to drop to 10-20 percent on Saturday. Due to these upcoming deteriorating conditions, a new Red Flag Warning has been issued for the North and East Bay Hills from 5 pm Friday through 11 pm Saturday. Winds will be locally gusty elsewhere in the hills Friday night and Saturday morning, but the magnitude of the winds outside the North and East Bay are not expected to be sufficient to warrant a Red Flag Warning. Winds will diminish in all areas Saturday afternoon and evening, although locally gusty north to northeast winds will persist in the North Bay Mountains through Saturday night. Warmer temperatures, along with continued dry conditions, are forecast for Sunday and Monday, but winds on those days are expected to be light. && of 4:50 PM PDT Thursday...Breezy northwest to north winds will continue overnight and into Friday as high pressure resides over the eastern Pacific. Winds will begin to subside overnight Friday and into the weekend. Strong winds this evening and tonight will result in steep fresh swell across the waters. Expect smoke from the North Bay wildfires to reduce visibilities at times -- especially over the San Francisco Bay. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Reyes to Pigeon Pt 0-10 nm SCA...Pigeon Pt to Pt Pinos 0-10 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm SCA...Mry Bay until 9 PM && $$ PUBLIC FORECAST: Dykema AVIATION: W Pi MARINE: Rowe FIRE WEATHER: Dykema Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Spokane WA
504 PM PDT Thu Oct 12 2017 .SYNOPSIS... Cooler and showery weather is expected for the rest of the work week. Snow will fall in the mountains and at elevations as low as 3000 feet. A slow warming trend and drier weather will arrive for the weekend and persist through at least Monday night. Much wetter weather is expected to arrive by Tuesday and persist through much of next week. && .DISCUSSION... Tonight through Friday night...Satellite imagery shows a cold upper trough over the region with a mid level wave over the WA Cascades tracking towards SE Washington this afternoon. Models are struggling with the details of this wave tonight with varying placements of heavier qpf but most solutions support the 12z ECMWF. which as of 18z had the best handle on the intensity and placement of this wave. The ECMWF shows a broad swath of light to locally moderate precipitation with the initial wave as it tracks across Eastern WA/N Idaho this evening followed by moist and unstable westerly flow into the palouse, Central Panhandle Mountains, and Blue Mountains overnight into Friday morning. The ECMWF places 0.75-1.00 inch of qpf in this area. The latest 19z HRRR run agrees with this idea...with a band of moderate to heavy showers in the form of valley rain and mountain snow over Benewah, Latah, and southern Shoshone counties overnight into Friday morning. Snow accumulations in these areas will range from 3 to 6 inches above 3000 feet...but its possible the mountainous terrain above 4000 feet around Clarkia and Deary could pick up 6 to 11 inches where upslope will be maximized. Snow levels may briefly lower down to 2500 feet where the band of heavier showers sets up. With the best lift passing over SE WA into the Central Panhandle Mountains...snow amounts don`t look as high for the northern mountains with 2 to 4 inches expected above 4000 feet with up to 2 inches possible between 3-4k feet. Winter weather advisories remain in place for several mountain zones. Showers will linger into Friday afternoon before coming to an end Friday night as drier air moves in from the northwest. This dry air will allow for chilly overnight lows...especially the northern valleys where a hard freeze is expected with lows in the upper teens to mid 20s. JW Saturday through Monday...Confidence is quite high that the unusually cold and unstable upper level low is expected to exit the region at the beginning of this period. This will bring dry weather to the entire region with the exception of a small chance of showers early Saturday near the Idaho/Montana border. The main forecast challenge during this period will be how widespread will valley fog become and if it does form how persistent will it be. Given that it`s still October, we don`t think it will be too widespread and it should readily burn off each day. Based on the expected precipitation during the next day or so, we expect to see most of the fog to form over NE Washington and the Idaho Panhandle Valleys. Temperatures will rebound from their current readings with highs in the 50s to middle 60s. Meanwhile lows will slowly moderate with widespread freezing temps on Saturday night climbing into the 30s to lower 40s for Sunday and Monday nights. Tuesday through Thursday...Models are in agreement that the dry ridge will break down via two distinct disturbances. The first comes through as a cold front on late Tuesday. This is a rather progressive feature and should not produce much precipitation. Rather it should produce a brief breezy period with most of its precipitation expected near the Cascade Crest and the Idaho Panhandle. The front will likely arrive too late to bring much cooling to the region, except perhaps near the Cascades. The second system is the much more dynamic of the two features as this one looks like it will be accompanied by an atmospheric river. Timing from this is less certain as the GFS delivers precipitation by Wednesday morning, meanwhile the EC and Canadian models hold off until Wednesday night. We hedged the forecast toward the latter solutions, but suffice it to say all solutions would support the potential for widespread moderate precipitation. Since this is associated with an atmospheric river, snow levels should be considerably higher than what we are dealing with now. Looks like most of the snow will begin at elevations of 6000 feet or higher followed by the threat of showers as low as 4000 feet beyond this period. fx && .AVIATION... 00Z TAFS: A weather disturbance will spread mountain snow and valley rain into the region tonight. MVFR/IFR ceilings and some brief LIFR conditions will be common over NE Washington, N Idaho, and the palouse through 18Z Friday. The potential exists for snow to mix with rain in KCOE aft 10Z. Also downslope flow off the Blue Mountains into KLWS should keep CIGS VFR. -RA will end aft 12-15Z but showers around the region will continue...mainly in the mountains...but could impact the eastern TAF locations. && .PRELIMINARY POINT TEMPS/POPS... Spokane 35 46 31 48 33 54 / 90 60 20 0 0 0 Coeur d`Alene 35 45 30 48 32 54 / 90 70 20 10 0 0 Pullman 35 45 32 49 34 56 / 100 80 20 0 0 0 Lewiston 40 52 35 56 37 62 / 80 60 20 0 0 0 Colville 35 49 23 50 27 54 / 60 50 20 0 0 0 Sandpoint 34 44 28 45 26 51 / 90 80 40 10 10 10 Kellogg 33 41 29 43 30 51 / 90 90 40 10 10 10 Moses Lake 37 55 27 56 32 60 / 60 20 0 0 0 0 Wenatchee 36 52 32 56 36 60 / 40 20 0 0 0 0 Omak 35 54 27 55 30 59 / 40 20 10 0 10 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory until 11 AM PDT Friday above 4000 feet for Northern Panhandle. Winter Weather Advisory until 11 AM PDT Friday above 3000 feet for Central Panhandle Mountains. WA...Winter Weather Advisory until 11 AM PDT Friday above 4000 feet for Northeast Blue Mountains-Northeast Mountains-Okanogan Highlands. && $$
Area Forecast Discussion
National Weather Service Paducah KY
713 PM CDT Thu Oct 12 2017 .UPDATE... Issued at 713 PM CDT Thu Oct 12 2017 Fog imagery shows the persistent low cloud cover is nearly stationary across the area, with a light ESE trajectory seen from the surface up through HRRR initialized 925mb data. The NAM and RAP/HRRR continue to be the best guidance available. They suggest our current cloud forecast is too quick with the clearing. Satellite confirms this to some extent. Will raise lows a few degrees east of an I-57, I-24, Highway 45 line. Our gridded forecast for cloud cover/clearing will be based close to the NAM/HRRR. More weight to the NAM. Left the fog mention over SEMO counties where clearing will hold. There may be some light fog elsewhere, especially close to the clearing line. CN && .SHORT TERM...(Tonight through Saturday night) Issued at 205 PM CDT Thu Oct 12 2017 Main forecast challenges will be the departure of the opaque cloud cover from the WFO PAH forecast area and the timing of the precipitation associated with the approach of the next cold front into the area late Saturday night (early Sunday morning). Isentropic lift and forcing remain marginal across the area, especially east of the surface ridge axis which extends from the Mississippi River northeast into Southwest Indiana. Even at 1 pm CDT, cloud thickness over parts of southern IL and parts of Southwest Indiana remain in excess of 1500 ft. Warm air advection tonight and Friday should continue to erode the cloud layer from above and below as the ridge axis slowly moves east. Given the weak advection, there may still be some cloudiness, albeit not 100 percent coverage, across the west Kentucky Pennyrile region and southwest Indiana, this evening. Where skies remain clear over southeast Missouri, could see some localized fog development overnight, even with very weak warm advection (most significant at and above the boundary layer). The influence of the ridge axis will likely yield to some diurnal cumulus cloud development early on Friday, before clearing out for the remainder of the day. Utilized the short range ensemble guidance (SREF) to address the timing, coverage, and intensity of rain late Saturday along and ahead of the approaching cold front. Limited instability aloft mitigated any differential mention of thunderstorms through Saturday night. .LONG TERM...(Sunday through Thursday) Issued at 205 PM CDT Thu Oct 12 2017 The only real weather maker in the long term period will be a frontal passage early Sunday which will bring our only chance for rain. Models have definitely sped up the timing of this front and associated rainfall. At 12Z Sunday, the NAM/GFS show the actual cold front in our far eastern counties with most of the precipitation post frontal. The ECMWF and Canadian indicate the front a bit further west at that time. The speed difference between models of the aforementioned front does not seem to have much affect on the forecast, as the best chances for rain for our area will still come between 12Z-18Z Sunday. Whatever precipitation is left Sunday afternoon, will be across parts of west KY. Not sure how much thunder will be involved as most of the instability will be tied to the front and directly behind the front. Will need to make changes to our going POP forecast however in order account for the more rapid arrival and departure of the precipitation. Will likely have to take rain chances out for Sunday night. Temperatures on Sunday will be tricky depending on how fast the cooler air filters into the area. We may be dealing with a non diurnal trend. Model guidance is suggesting falling temperatures through the morning hours so our high will likely be first thing in the morning. By late Sunday afternoon, a large 1028-1030mb surface high will be situated over Kansas and Oklahoma. This sfc high will start migrating eastward Sunday night and into Monday, really helping to dry things out locally. The center of this sfc high pressure system will be overhead by late Monday night into Tuesday morning. With clear skies and calm winds, Monday night into Tuesday morning should be our coldest, with lows dropping into the lower to mid 40s. High pressure will dominate for the rest of the week, which will aid in keeping any chances for precipitation at bay. Temperatures will remain in the 70s for highs and upper 40s to lower 50s for lows from Tuesday and beyond. && .AVIATION... Issued at 640 PM CDT Thu Oct 12 2017 The back edge of a widespread area of MVFR cigs was nearly stationary near the Mississippi River early this evening. Low level winds are so weak that not much movement is expected through the early morning hours. MVFR cigs are forecast to persist at most taf sites through at least mid-morning Friday. The exception is kcgi, which was right on the clearing line early this evening. The clearing line should budge just a little east of kcgi this evening. Some fog is likely at kcgi after skies clear, with IFR vsbys likely at times early in the morning. As winds become southeast on Friday, VFR conditions are expected at all sites as the clouds move out. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ SHORT TERM...Smith LONG TERM...CW AVIATION...MY
Area Forecast Discussion
National Weather Service Raleigh NC
1000 PM EDT Thu Oct 12 2017 .SYNOPSIS... A backdoor cold front will settle south of North Carolina tonight. Behind the front, a cool high pressure area will build down the East Coast through Saturday. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 PM Thursday... The backdoor cold front has pushed south of our region into SC this evening. A line of showers and thunderstorms was preceding the front, but well south of Fayetteville and moving south. CAA has begun in earnest across central NC with temperatures now in the lower 60s across the northern NC Piedmont. That combined with the NE breeze at 8-15 mph was creating "natures air conditioning" considering the previous 5 days of record warm and moist conditions. Low overcast was observed over most of central NC with the overcast spreading SW with time. Other than patchy drizzle, there have been a few showers over the western Piedmont back into the Mountains, but mostly light and scattered thus far. Low level moist isentropic upglide is forecast to increase and deepen overnight with an increase in the areas of light rain and drizzle, especially over the western Piedmont. The latest HRRR indicates scattered showers over the western Piedmont as well through daybreak. QPF of less than 0.25 is expected in the west, with only trace or 0.01 in the east with the drizzle. Lows generally 55-60 NE ranging to 65 south. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 315 PM Thursday... The damming wedge will hold in place through central NC through Fri and Fri night, with low level stability reinforced by an anticyclone just above the surface-based stable pool extending through the mid levels. Heating will result in some lifting and breaks in the stratus through the day across the southern and eastern sections, along the shallower edges of the wedging ridge. Isentropic upglide wanes during the morning, leaving just small chances of patchy light rain through the day, mainly in the NW. Low level thicknesses will still be slightly above normal, but with the cloudiness, highs should be closer to normal, from around 70 N to upper 70s to near 80 far SE. Shallow fog is possible Fri night, as a lack of clouds aloft allows for good radiative cooling down to the dewpoint within light winds. Lows 59-65. -GIH && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 245 PM Thursday... Wedge airmass will be cut off from reinforcing cool air advection as the surface ridge progresses offshore well east of the Mid Atlantic. As such, the cool air will be undergoing modest erosion from the top down, and the south and east may break out during the afternoon. Deeper cool and moist axis across the western Piedmont will likely hold the cloudiness in all day, with highs stalling in the mid 70s in the northwest while the southeast reaches low to possibly mid 80s. Return flow will be underway as the cooler airmass will be scoured and mixed out by Sunday, with highs rebounding to the low and mid 80s. Latest GFS is ~6 hours faster bringing our long awaited cold front across the mountains Sunday night. This timing difference won`t be a huge concern, as the front will be moving quickly and be strongly sheared, which will just about eliminate any Gulf connection to provide additional moisture advection. In addition, instability will be very low as well due to the fronts moving through early in the day, so potential for strong convection will be very limited and confined to the southeast in the early afternoon. Cold air advection will be underway early as well, with highs barely reaching 70 in the northwest, with some very low 80s southeast. Cool high pressure settles in Monday night through midweek...with highs Tuesday and Wednesday mostly in the mid 60s north to very low 70s south...warming a bit by late week to the low and mid 70s as the airmass modifies. Mins will be downright chilly....falling mostly to the mid and upper 40s each morning from Tuesday through Thursday. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... As of 810 PM Thursday... 24 Hour TAF Period: Adverse aviation conditions are expected to continue through the 24 hour TAF period, as a CAD airmass encompasses all of central NC. This will lead to east to northeasterly low level across the area with lowering cigs overnight. Expect cigs will fall in to the IFR category later this evening/into early Friday morning, with even some LIFR cigs early Friday/Friday morning. Patchy drizzle and light rain will also be possible tonight into Friday, with the best chance at KGSO/KINT. Cigs will slowly increase some on Friday, though likely remaining IFR at KGSO/KINT and MVFR at KRDU. Cigs may briefly rise late in the day at KFAY AND KRWI to VFR. Outlook: IFR/LIFR conditions should return for Fri evening through much of Sat morning. Slow improvement of cigs through the MVFR category to low-end VFR is expected Sat afternoon. Sub-VFR conditions may return late Sat night through daybreak Sun but won`t be as thick or long-lasting as tonight`s poor conditions. VFR conditions are expected Sun, but a strong cold front pushing through Sun evening will bring sub-VFR conditions Sun night through early Mon. Improvement to VFR is expected during Mon, with clearing skies Tue. && .CLIMATE... Record high minimum temps for October 12: GSO: 64 in 2002 RDU: 68 in 1990 FAY: 68 in 1990 && .RAH WATCHES/WARNINGS/ADVISORIES... None. $$ SYNOPSIS...Hartfield NEAR TERM...Badgett SHORT TERM...Hartfield LONG TERM...mlm AVIATION...BSD/Hartfield CLIMATE...MWS
Area Forecast Discussion...Updated
National Weather Service Tucson AZ
420 PM MST Thu Oct 12 2017 .SYNOPSIS...Expect isolated showers and thunderstorms southeast of Tucson early this evening. Dry conditions with above normal daytime temperatures will then prevail into the middle of next week. && .UPDATE...KEMX WSR-88D detected isolated 40-50 dBZ echoes across portions of Cochise County at this time, and somewhat stronger echoes were detected near the International border adjacent Cochise County. Although a dry near-surface regime exists such that measurable rainfall chances are quite low, a few lightning strikes have been detected, particularly just east of Coronado National Memorial. Based on radar trends as well as a couple of recent HRRR solutions, have opted to insert isolated showers and thunderstorms through 13/03Z (8 pm MST) generally southeast of a San Simon- Cochise-Sierra Vista arc. && .DISCUSSION...Latest visible satellite imagery depicts clear skies west of Tucson with mostly clear to partly cloudy skies from Tucson eastward under a cumulus field with a few build-ups. This matches up nicely with the moisture fields across the area as satellite derived PWAT values are 0.75" to 1.00" east of Tucson with lesser values to the west. KEMX radar imagery is showing just a few weak echoes across Cochise County. Will keep PoPs below 10 percent but a sprinkle or two can`t be completely ruled out this afternoon into early this evening. In the broader picture, the forecast area lies between an expansive anticyclone aloft across the southeast and Gulf Coast states and troughing across the Pacific Northwest with southwesterly flow aloft currently in place. Limited moisture will tend to hang on to the far southeast portions of the state into Friday but once again not really expecting much more than a few build-ups. Thereafter, even with the storm track well to our north, a shortwave pushing across the northern Rockies will push in some drier air area-wide by Saturday with westerly flow. This theme of westerly flow aloft will continue through Wednesday as we remain between high pressure aloft across northern Mexico and the storm track across the northern tier of states. A weak southern stream system is progged to move into the region on Thursday but there are some timing and amplitude differences. Have introduced slight chance PoPs on Thursday for northern areas. Otherwise, an easterly push with a back door cold front will move in Sunday with some breezes and a few degrees of cooling into early next week. Locales from Tucson westward will continue with well above normal temperatures for mid October. && .AVIATION...Valid thru 14/00Z. Isolated -TSRA/-SHRA generally southeast of a San Simon-KFHU line through 13/03Z. Otherwise, scattered to broken clouds at 8k-12k ft AGL KTUS vicinity eastward into this evening becoming clear skies to few clouds above 10k ft AGL area-wide later tonight into Friday morning. Scattered to broken clouds at 8k-12k ft AGL mainly east of KTUS Friday afternon. Surface wind wly/nwly 10-18 kts early this evening becoming variable in direction less than 12 kts after 03Z and continuing into Friday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated showers and thunderstorms early this evening across the southern portion of Fire Zone 152. Otherwise, dry conditions into the middle of next week. Expect terrain driven winds generally less than 15 mph, although some gusty east to southeast winds may occur east of Tucson on Sunday. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Francis DISCUSSION...GL AVIATION/FIRE WEATHER...JKP Visit us on Facebook...Twitter...YouTube...and at