Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/11/17

Area Forecast Discussion
National Weather Service La Crosse WI
547 PM CST Fri Feb 10 2017 .SHORT TERM...(Tonight through Saturday night) Issued at 238 PM CST Fri Feb 10 2017 Main fcst concerns this period are precip chances mainly Sat afternoon/evening, temperatures thru the period. 18z data analysis had a 994mb low near KINL, tracking east along the MN/Ont border. Broad south and SW sfc-850mb flow across the region south of this low at mid-day, spreading strong warming north/east across MN/IA/WI. Cloud cover mainly a sct-bkn veil of cirrus, allowing for plenty of sunshine to reach the ground across most of MN/IA/WI. Where the ground was snow-free or nearly so across parts of MN/IA, 18z temps were already warming into the low-mid 40s, with low-mid 30s common over our mostly snow covered fcst area. Model runs of 10.12 initialized well. Solutions, at least at 500mb, remain similar for stronger shortwave to move across the nortern Rockies tonight, into the northern plains Sat then into the Upper Midwest Sat night. Trend by Sat night favors faster of the earlier model runs, with the mid level trough axis to near the MS River at 12z Sun. Some detail differences by Sat afternoon/night, but overall the short-term fcst confidence is good this cycle. For the short term, a dry, quiet, mild night tonight with the sfc- 700mb layer remaining on the dry side and actually dominated by WNW cold advection flow. Moisture/cloud increase tonight above 700mb with any forcing/lift remaining on the weak side in zonal flow over the region. Forcing/lift increases across the area Sat with approach of the mid level shortwave, with a weak/mdt band of mid level FN convergence developing/moving somewhere across the central/south parts of the fcst area Sat afternoon/evening. 925-850mb flow remains NW-N Sat with weak cold advection, with model soundings/x-sections showing the 925-800mb layer struggling to saturate with the weak/mdt lift above it. Area radars should be lit up pretty good with returns by Sat afternoon/evening but question is how much of this will actually reach the ground with the drier air below 800mb. Some model consensus there will be a brief period of moisture increase in the sfc-800mb layer sometime Sat night with approach of the shortwave trough and PV advection/dynamic cooling of the column. Expect there will be a rather narrow band of precip reaching the ground late Sat afternoon/evening were the strongest of the lifting mechanisms overlap. This could be anywhere from along I-90 to a KOLZ-KDBQ line. For now small chances of precip these areas Sat afternoon then more 20-40% chances Sat evening into the overnight hours reasonable. Evaporative cooling into the dry sub-cloud layer would drop max wet- bulb zero values into the -1.5C to +2.5C range by Sat afternoon, with potential of a wintry mix of precip types. With weaker lift and boundary layer temps looking be in the upper 30s/low 40s, bulk of precip chances Sat afternoon into early Sat evening as -RA. With both dynamic and BL cooling Sat night, precip would gradually change to -SN thru Sat evening into the overnight, until mid level drying behind the 700mb trough axis warms the cloud tops to above -10C. Perhaps a small -FZRA chance toward Sun morning, but by then bulk of the lift is gone along with precip chances. A blend of the guidance lows/highs for tonight thru Sat night, with lows tonight/Sat night near/above the normal highs, looks reasonable. .LONG TERM...(Sunday through Friday) Issued at 238 PM CST Fri Feb 10 2017 For Sunday thru Monday night: main fcst concerns this period are mild temperatures. Tight consensus among 10/12z models for the trough axis to move quickly east of the area Sun, then shortwave ridging to build across the region Sun night. This ahead of a stronger northern stream shortwave to drop toward/across Lk Superior Mon/Mon night, with the mid level flow strong NW by 12z Tue. Fcst confidence for Sun thru Mon night is good this cycle. With the sfc-mid level trough quickly exiting east Sun, any lingering precip chances Sun morning over the NE end of the fcst are very early in the day. Deep layered subsidence to spread across the area Sun, but will have to watch for some lower moisture/clouds that could get trapped under the subsidence inversion thru much of Sun. With anti-cyclonic low level flow/high pressure building in, consensus of decreasing clouds thru Sun is reasonable. After a bit of a post low/trough cool down Sun, the next round of 925-850mb warm advection quickly spreads across the area Sun night/Mon under the shortwave ridging. 925mb temps back to near/above 0C by Mon afternoon. If mixed that deep would support highs in the 40s. With what is looking to be mostly sunny skies and SW winds of 10-20 mph for mixing, trended Mon highs 2 to 3 degrees above the consensus. for now. With a deep, dry airmass over the area Mon, and the lower level source region from the central/northern plains, sfc-700mb trough axis with the shortwave dropping across Lk Superior looks to do little more than bring a wind shift to the NW Mon night. Other than warming highs a few degrees Mon, consensus highs/lows for the rest of the Sun-Mon night period look to be in the ballpark. For Tuesday through Friday (days 4 to 7): main fcst concerns this period are generally temperatures. Medium range model runs of 10/00z/10.12z are in decent agreement on a stronger norhtern stream shortwave dropping into the western great lakes Tue, with a mid level low then migrating across the great lakes into New England Wed/Thu. All this sets the area up under stronger NNW mid level flow for Tue-Thu as some troughing lingers over the great lakes and weak secondary shortwaves ripple down thru the flow. Lesser model detail agreement by Fri, but consensus has the pattern progressing as strong Pac energy moving onto the west coast shoves rather strong ridging eastward into central NOAM. Fcst confidence for Tue-Fri is average to good this cycle. Tue-Fri continues to trend as a dry period with the NNW flow aloft and the main shortwave energy passing north/east of the fcst area. Lower level trough/front passes with the great lakes shortwave Tue. Perhaps a small -SN chance NE of I-94 on Tue with its passage, but looks mainly usher a cooler airmass/Can high pressure into the region for Wed/Thu. The cooling only looks to send 850mb temps back to near normal for Wed, with low level warm advection already returning for Thu. This mainly dry W to SW flow from the central/ northern plains. With the mid level ridging being pushed into the plains Fri, mdt/strong low level warm advection continue into Fri. 925-850mb temps progged to back to near/above 0C by Fri. Depending on depth of diunral mixing, highs Fri could be well into the 40s once again. For now, model/ensemble consensus of highs/lows for Tue thru Fri looks good, remaining above normal for perhaps all but Wed as the coldest core of low level air behind the Tue shortwave moves across the region. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 547 PM CST Fri Feb 10 2017 VFR conditions expected through Saturday, although the ceilings will be lowering through the day. An area of low pressure currently over Colorado, will move east into central Illinois by late Saturday afternoon as a weak short wave trough works across the Upper Midwest. There should be good frontogenesis north of the surface low and this forcing combined with the lift from the short wave trough will work to saturate the column and cause ceilings to lower. There is a lot of uncertainty whether this forcing will be strong enough and remain over the area long enough to produce any precipitation. Forecast soundings from the 10.18Z NAM and 10.21Z RAP indicate a very dry sub cloud layer will be in place that should cause most of the precipitation to evaporate and stay with a dry forecast through the period. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...RRS LONG TERM....RRS AVIATION...04
Area Forecast Discussion
National Weather Service Denver/Boulder CO
901 PM MST Fri Feb 10 2017 .UPDATE... Issued at 900 PM MST Fri Feb 10 2017 Not many updates needed to the forecast for the next 24 hours. Winds have weakened across the foothills and I-25 urban corridor and should remain that way overnight. Winds will remain across the Plains as well until the cold front impacts Colorado. Latest high-res model guidance has the wind shift entering Colorado from the north around 8 AM and reaching Denver metro around 10 AM, and given this is not an arctic front the timing seems reasonable. By noon the front should reach Limon and clear the BOU CWA early afternoon. Behind the front winds will pick up significantly out of the north and northeast at 15-25 mph and keep temperatures in check...highs tomorrow in the mid 50s look on track most areas, though Lincoln County could warm into the 60s before the front arrives. In the mountains strong WSW winds will continue overnight in the 25-35 mph range with a few gusts to 50 mph possible across the highest mountain passes above 9500 feet. HRRR and ESRL HRRR have precipitation beginning in the next few hours and latest radar/satellite data show increasing echoes across western Colorado moving east. Increased PoPs in the mountains to account for the earlier arrival of precipitation. Temps are still warm across the mountain valleys so it may start off as rain, but expect it change over to snow quickly. && .SHORT TERM...(This evening through Saturday) Issued at 331 PM MST Fri Feb 10 2017 Wind event across the forecast area has been slowly winding down through the afternoon as temperatures climbed to record levels for the month of February. Still seeing wind gusts of 45 to 60 MPH in the foothills of Boulder County and gusts to 20 to 30 MPH on the Plains and over the Palmer Divide. Fire danger levels remain elevated due to the warm temperatures, low humidities and gusty winds. Will let the Red Flag Warning remain in effect until the early evening, when temperatures and winds come down. In the mountains, moisture will be increasing from the west during the evening hours with a mix of rain and snow expected to begin by midnight. Mountain temperatures are warm this afternoon, but as the moisture increases this evening and precipitation begins, evaporative cooling of the column should be enough to keep any mountain rainfall short-lived. Most mountain areas should be receiving snow by sunrise. Models keep the precipitation from the approaching system in the mountains, due to the strong westerly component in the flow pattern. Thus only slight chance pops are included on the plains. Snowfall amounts in the mountains could be some 2 to 4 inches by sunrise and another 4 to 8 inches through tomorrow afternoon. Will not issue any highlights at this time since weather systems coming from the southwest tend to favor the San Juan mountains, and reduce the amount of snow that falls in Grand and Summit Counties. The other story tomorrow will be the much cooler temperatures across the plains, as highs in the lower to mid 50s will seem downright chilly after today`s record breaking numbers. .LONG TERM...(Saturday night through Friday) Issued at 331 PM MST Fri Feb 10 2017 Models show a southwesterly jet maximum over the CWA Saturday night. There is weak upper ridging in place Sunday with a closed low over northern Baja Mexico by late afternoon. A weak upper trough is progged to move across the CWA on Monday. Weak northeasterly winds aloft are progged Monday night. There is benign synoptic scale energy for the CWA on the QG Omega fields Saturday night through Monday night. There is upslope in the lower levels Saturday night. Southerly winds are progged Sunday and Sunday night. There is more upslope progged Monday and much of Monday night. For moisture, there is quite a bit progged for the CWA in the mid and upper levels Saturday night, but not much in the lower levels. There is better low level moisture on Sunday, but its not as deep as Saturday night. Sunday night dries out quite a bit, with a tad of moisture lingering in the high mountains. There is some upper level moisture around here and there Monday and Monday night. The QPF fields show a tad of measurable precipitation over the southern CWA Saturday night and over just the southwestern CWA Sunday in the day. There is a little bit more over the southern high mountains on Monday. For pops, will go with "likely"s for most areas of the CWA Saturday evening. Pops will decrease overnight, with the best remaining over the high mountains south of I-70 and Park County. By Sunday, there will be minor pops relegated to the southwest corner of the CWA. For temperatures, Sunday`s highs are 4-7 C colder than Saturday`s. Monday`s highs are 2-5 C warmer than Sunday`s. For the later days, Tuesday through Friday, models have upper ridging and fairly weak northerly flow aloft all four days. There is little moisture. Temperatures will be above seasonal normals. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 900 PM MST Fri Feb 10 2017 Winds across all three terminals have finally weakened this evening. Expect westerly winds all three terminals, with DEN and APA shifting to a drainage pattern after 08Z. BJC should stay westerly overnight. On Saturday a cold front will impact the three terminals. High res model guidance has it impacting DEN around 17Z, with APA and BJC less than an hour after that. Winds will shift to the northeast behind the front. VFR conditions expected with the frontal passage given the still sizable T/Td speads near the surface. Rain chances increase at all three terminals after as the cold air deepens and lift develops associated with the jet streak, roughly after 23Z. MVFR conditions are possible after 23Z as well with the precipitation and increased moisture in the low- levels. At this point the precipitation should fall as rain until 06Z on Sunday. Any snow amounts look to be an inch or less at the three terminals, with the best chance of accumulating snow at APA and BJC with deeper low-level upslope flow. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Schlatter SHORT TERM...Dankers LONG TERM...RJK AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Taunton MA
954 PM EST Fri Feb 10 2017 .SYNOPSIS... A warm front approaches the region tonight and produces a period of light snow with 1 to 3 inches of accumulation likely by Saturday morning. Low pressure then brings a wintry mix of precipitation and heavy snow to the area Sunday into late Sunday night or Monday along with strong winds as low pressure intensifies rapidly east of Cape Cod. Dry weather likely returns Tuesday and then another chance of snow Wednesday and/or Thursday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 10 pm update... Radar confirms snowing aloft across southern New England but very dry air near the surface (dew pts in the single digits) is eroding the snow before reaching the ground. New 00z NAM has snow overspreading the region between 10 pm and 1 am from west east. Based on upstream observations this seems reasonable. Steadiest snow appears to fall between 1 am and 4 am. 00z NAM as well as latest runs from the HRRR and RAP continue to generate a few tenths of qpf overnight with snow ending 7 am to 10 am across the region. So overall not much change from previous forecast with the expectation of an inch or two of snow for most locations, isolated amounts up to 3 inches possible. By no means a lot of snow but enough for snow covered roads and slippery travel into Sat morning. Previous discussion below. =============================================================== Previous Discussion... No major changes with the forecast for tonight. Still appears to be a good overrunning setup tonight as a warm front approaches our region. No real question on precipitation type, it will be a light snow. The most likely window for snowfall should start between 10 pm and 1 am, and end later Saturday morning. Most of the snow should fall tonight. Expecting a general 1 to 3 inches of snow, with locally higher amounts up to 4 inches possible. It`s marginal, so no Winter Weather Advisories have been issued. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday...Precipitation gradually ends from west to east Saturday morning. Most of the region should be dry by mid morning. Developing south winds may be strong enough to push temperatures above freezing, which means the precipitation may end as a brief period of rain or a rain/snow mix towards the south coast of New England, particularly across Nantucket. Not a big storm by any stretch but snow covered roads will result in slippery travel Saturday morning. Near normal temperatures. Saturday night...This is where the forecast starts getting tricky. Surface temperatures should be sufficiently cold at the surface to support snow across much of southern New England. One issue will be how quickly we can moisten the dendritic snow growth region, another will be low level temperatures above the ground. The lack of moisture in the snow growth region might lead to a period of freezing rain or freezing drizzle early Sunday morning. The thermal profiles may also contribute to that potential. It`s also possible we could get a wintry mix across southern New England, with rain toward the coast and a snow/sleet mix farther inland. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * Intense coastal storm will lead to multi-hazard system occurring Sunday into Monday * High pressure on Tuesday into Wednesday * Low confidence on another coastal system Thursday into Friday Pattern Overview... 12z Guidance is in general agreement for the medium range but begin to diverge for the long term. Building ridge across the northwest CONUS will keep New England in a trough pattern for the remainder of the period. Appears winter is here to stay. Attention first towards weak ridging on Sunday morning as dynamic shortwave moves over southern New England. This wave will develop and bomb out a surface low just to the east of the area. This system will result in several hazards for Sunday into Monday. Northwest flow aloft will continue across New England before another dynamic shortwave moves over the region. This is more uncertainty with this system, especially with the low level features. The GFS appears more progressive and to late to capture southern Plains surface low into a coastal storm, where the EC is more amplified resulting in coastal low pressure late Wed into Thursday. Ensembles are also indicating large spread so low confidence beyond Wednesday night and beyond. Sunday into Monday... ** Heavy snowfall possible north of the Mass Pike ** Strong wind gusts across eastern Mass ** Coastal Flooding issues are possible especially near the Cape and Islands Digging trough and closed upper level low will approach southern New England on Sunday/Monday. Ahead of this system, WAA will lead to overrunning Sunday morning resulting in wintry precip especially across CT/western MA. As the system advances, both 500 mb and 700 mb closed low strengthens considerable, developing a surface low south of the region on Sunday. As upper level jet dynamics moves into the region, anticipate the surface low to bomb out east of southern New England by Sunday night. This system has some incredible dynamics and impressive low level baroclinic zone as well as a hint of rather extreme deepening with a tropopause fold. Still some difference in the placement of the low as the GFS is on the eastern side of the envelope, but both of the deterministic and ensemble guidance is pin-pointing this low to develop south of the region before strengthening east of the area by Sunday night/Monday morning. Biggest question with this system is the thermal profiles. Placement of the low can change temperatures a few degrees which could result in different p-types. Consensus is snow north of the Pike for the event, with the potential for wintry mix across northern CT and into NW RI. Rain along the I-95 corridor towards the Cape and the Islands as the low moves eastward bringing in warmer air. As the low moves east of southern New England and strengthens considerably, appears that strong CAA will move-in collapsing the temperature profile and changing the p-type to all snow by Sunday night/Monday morning. Again the p-types can change in the coming days but this is general consensus as of now. Went ahead an issued a winter storm watch with surrounding WFOs. The watch is located where highest confidence of 6+ inches of snow could occur. There is the potential that the watch may be expanded if the thermals are cooler than currently advertised. Aside from the watch, winter weather advisories may be needed for snow, sleet, freezing rain or the combinations of the three. Still have a few more guidance cycles to determine this outcome. As the surface low undergoes bomb cyclogenesis, the pressure gradient will tighten significantly. This will result in 925 mb LLJ reaching between 40-50 kts. Steep Lapse rates and good mixing will help bring these strong gusts down to the surface. Appears that locations across eastern MA has the best shot to see wind gusts near 40-50 mph. This will result in wind headlines as well as blowing and drifting snow on Monday. Northerly to northeast winds on Monday will result in building seas and storm surge. This surge combined with the seas and wind gusts could result in minor to moderate coastal flooding across the northern shoreline of the Cape, Cape Ann and Nantucket. Coastal erosion is also possible. Overall still some uncertainties with this system. However confidence is increasing in heavy snow north of the Pike and gusty winds across the east coastal MA. More details will be resolved in the upcoming forecast so stay tuned. Tuesday and Wednesday... Weak ridging aloft will yield to a break in the precipitation on Tuesday. Another weak wave will move through the area on Wednesday which could out put some showers across southern New England. Low confidence on Wednesday forecast as models are diverging on timing and strength. Wednesday night into Thursday... Lots of uncertainty with this system as the EC brings another impressive coastal storm to the region while the GFS is dry. Ensembles guidance in both the GEFS and ECENS are still all over the place as the potential outcomes to this system. Will need to watch this timeframe over the next several days to get a better idea of what could occur. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 03z update... Not much change from previous TAFs. Snow arrives 03z-06z with steadiest snow 06z-09z and then tapering off 12z-15z. Accumulations mainly an inch or two with a few locations up to 3" possible. Snow will be accompanied by mainly MVFR conditions with isolated brief IFR possible. Previous discussion below. ================================================================= Tonight... VFR at sunset but MVFR conditions in light snow arriving across western sections of CT/MA toward midnight, and then eastward into RI and eastern MA after midnight. Snow intensity may approach moderate toward 12z Sat. Saturday... MVFR much of the day. Light to moderate snow in the morning, ending as some light rain across CT/RI and southeast MA in the afternoon. Storm total snow accumulation of 1-3 inches. Saturday night...Moderate confidence. Areas of MVFR-IFR cigs and vsbys may occur. Anticipate a few areas of -SN possibly mixed with sleet south of a kBOS-kCEF-kBAF line. Patchy -FZDL or -FZRA possible as well. KBOS TAF...High forecast in trends. May see lingering snow showers into the day Saturday. KBDL TAF...High forecast confidence. Outlook /Sunday through Wednesday/... Sunday through Monday...Moderate Confidence. MVFR/IFR to start as wintry mix moves into the region. Anticipate different p-types across the terminals with snow to the north and rain to the south. Conditions will deteriorate through the day and into the evening to IFR/LIFR as any rain switches to snow. Anticipate gusty northerly winds by Sunday night into Monday near 30-50 kts. BLSN is possible on Monday. Tuesday...VFR. Wednesday...VFR with the potential for MVFr in any passing snow shower. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 10 pm update... Tranquil weather with ridge of high pressure moving across the waters. Warm front approaches overnight and results in light snow with vsbys 1-3 miles. Otherwise light winds and modest seas. Previous discussion below. ==================================================================== Short Range /through Saturday/...High forecast confidence through Saturday. Tonight... Winds diminish as high pressure moves across the waters. However, snow overspreads the region, reducing vsby to 1 to 3 miles. Saturday... Weak low pres tracks directly over southern New England. This results in light ESE winds becoming variable. Snow and rain in the morning limit vsby but improve by afternoon on most waters. Saturday Night...Winds expected to remain less than 25 kt. However, increasing north winds and arriving swell may lead to rough seas across some of the eastern coastal waters. Outlook /Sunday through Wednesday/... Confidence...Moderate. ***Intensifying storm system early Monday will result in high seas and near storm force wind gusts*** ***This could become a very dangerous scenario for mariners on waters east or southeast of New England.*** Building seas across the region as surface low south of New England begins to intensify and approaches the Gulf Of Maine. This type of storm and how quickly is strengthens will result in the risk for strong northerly winds near storm force, and waves in excess of 15- 20 feet for late Sunday night into Monday. Went ahead an issued a storm force watch for immediate northerly ocean zones where confidence is highest. Tuesday...Winds should have diminished and seas should continue to gradually subside. Wednesday...Another coastal low system is possible on Wednesday. This may result in build seas and winds across the waters. && .TIDES/COASTAL FLOODING... Risking is increase for the potential for coastal flooding around the Monday midday high tide. 925 mb northerly jet increases to near 40-50 kts. The potential for these gusts to mix down as well as build seas could result in a surge that will impact the along the north side of the Cape (Sandwich to Dennis) and Nantucket Harbor. Still some uncertainty with this system but appears that minor to moderate coastal flooding is possible. However all of this will depend upon exact positioning and timing of a potential explosive development of an intense coastal storm. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Storm Watch from Sunday morning through Monday evening for MAZ002>006-008>012-026. RI...None. MARINE...Storm Watch from late Sunday night through Monday evening for ANZ250. Small Craft Advisory until midnight EST tonight for ANZ250-254- 255. Small Craft Advisory until 10 PM EST this evening for ANZ256. && $$ SYNOPSIS...Belk/Dunten NEAR TERM...Belk/Nocera/Dunten SHORT TERM...Belk LONG TERM...Dunten AVIATION...Belk/Nocera/Dunten MARINE...Belk/Nocera/Dunten TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service State College PA
1022 PM EST Fri Feb 10 2017 .SYNOPSIS... A storm system will move through the region Saturday night and Sunday. High pressure will return for early next week. After a mild weekend, the cold front associated with this storm will bring cooler conditions for Monday. && .NEAR TERM /UNTIL MIDNIGHT TONIGHT/... Warm advection is helping support an area of light precip moving out of eastern Ohio into western Pa. The HRRR has some diminishing returns over the next few hours while the remainder of the deterministic models show no QPF. I inserted the chance for some flurries but no actual measurable precip for the overnight. The southerly flow will allow temperatures to stay steady or rise as the night progresses. && .SHORT TERM /MIDNIGHT THROUGH 6 PM SATURDAY/... The snow will slip eastward and out of our hair this evening. An upslope component to the southwest wind may lead to a few flurries or sprinkles tonight, but clouds are the more-likely result for the west. Temps should be rising by midnight, and mins will likely be early in the night for most locations. Mid 20s to upper 30s will be around by Sat morning, and widespread 40s and lower 50s S are expected for the afternoon. However, a marked increase in moisture will occur on Saturday evening with dewpoints into the 30s and lower 40s by midnight. Rain should develop over the west in the mid to late afternoon. This will spread to the east and get everyone wet. Very high POPs are in order for a 12 to 15 hour period. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Another highly energetic shortwave aloft will dive SE from the upper great lakes to impact much of the NE U.S. for the second half of this upcoming weekend. Mid-level warm advection and increasing large-scale upper diffluence late Saturday night and Sunday will lead to warm advection precip as an area of high PWAT air (in excess of 1 inch) is transported NE from the Ohio River Valley and lifted over a warm front (banked along the front range of the Alleghenies. This front will have a tough time moving to the NE across our CWA and scouring out the dense, shallow cold air trapped across PA to the east of the Allegheny front. Went a few to svrl deg F below the NBM`s fcst highs for Sunday (Esp across the Susquehanna RIver Valley). Model trends over the past 24 hours brought the Clipper/sfc low track further to the south, and somewhere across the southern half of PA or northern VA during the day Sunday. The 12Z GFS is the weakest and furthest north with the low track, while the 10/09Z SREF, NAM and EC are all quite similar with the track of the main low just south of the Mason/Dixon line, followed by rapid intensification off the NJ/Southern New England Coasts Sunday Evening into early Monday. Precip type will be a difficult call at several phases of the storm (Clipper). Areas of -FZRA (and even a little sleet or wet snow at the start near and north of RT 6) are likely across the northern mtns of PA during the Day Sunday, before colder air sweeps SE acrs the commonwealth and changes precip back to a few periods of snow or snow showers with minor accums in most places by Sunday evening. Periods of plain rain are expected across the southern half of the state...with pockets of freezing rain possible near the I-80 corridor. The increasingly strong and gusty winds are another concern as the sfc low rapidly deepens just off the New England Coast Sunday night and Monday. Northwest wind gusts of 35-45 mph range (with locally higher gusts possible) appear quite likely later Sunday night into Monday. Still plenty of time to assess the situation before pulling the trigger on a wind advisory. Collaborated with surrounding WFOs and WPC WWD Graphics to paint in some light ice accums Sunday. No FZRA or Winter Weather Advisory planned yet, but will continue to mention it in the HWO. A narrow north/south wedge of miler air will follow the passage of an inverted trough late Sunday afternoon, prior to the arrival of the deeper colder air. This will cause a quick/brief jump in temps back to near normal highs across much of the region. However, the Scent Counties and Laurel Highlands will surge into the 40s to l50s respectively. Snow showers and perhaps some brief squalls will accompany the passage of the main upper vort max/mid level thermal trough Sunday night with additional minor accums of a coating to 1/2 inch throughout the Ridge and Valley Region (and perhaps a few inches across the snowbelt of NW PA and also the Laurel Highlands. Winds will gradually slacken Mon night into Tuesday as a ridge of high pressure slides east from the Ohio Valley. An area of low-mid level Warm Advection induced light snow may brush the NW mtns Tuesday as another (initially weak) nrn stream wave approaches from the Upper Glakes. 12Z EC continues its trend of being the most aggressive with sfc low development to the South of PA during the midweek period as it`s the outlier model with substantial phasing of nrn and srn stream energy over the eastern U.S. and SERN Canada. Went the mid ground between the aggressive EC and a host of other model data (w/respect to POPS for snow). 12Z GEFS keeps the 2 separate stream waves detached with our region dominated by the nrn stream for the second half of the week. Another shot of cold air with gusty NW winds and mtns snow showers will close out the week with low pressure deepening to some degree near or off the New England Coast. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... A band of light snow associated with a warm front over the Great Lakes has lifted north of the region this evening. Upstream observations and model soundings support widespread VFR conditions for the rest of the night. The only exception may be developing low CIGs toward dawn at BFD/JST. A strong SW flow aloft will create a period of LLWS over much of the region overnight. Model soundings indicate the stronger winds will begin mixing to ground level at JST by around 03Z, ending the threat of LLWS there. Elsewhere, model soundings indicate the inversion height and associated shear will occur above 2kft at IPT, so no LLWS expected there overnight. An increasingly moist westerly flow will develop Saturday, likely resulting in IFR/low MVFR CIGs at BFD/JST, where the moist flow rises over the Allegheny Plateau, and possible MVFR CIGs east of the mountains. Outlook... Sun...Daytime rain/low CIGs likely. Evening shsn/reduced vsby likely at BFD/JST and improvement further east. Mon...Windy. AM shsn/reduced vsby possible BFD/JST. Tue...No sig wx expected. Wed...Snow showers/VIS reductions possible BFD/JST. && .EQUIPMENT... KFIG surface observation will be off line until further notice due to failed power feed. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...Dangelo/Gartner LONG TERM...Lambert AVIATION...Fitzgerald EQUIPMENT...
Area Forecast Discussion
National Weather Service Lincoln IL
836 PM CST Fri Feb 10 2017 .UPDATE... Issued at 836 PM CST Fri Feb 10 2017 A weak boundary approaching from the NW continues to help shift the surface pressure gradient responsible for today`s windy conditions off to the southeast. Meanwhile...low pressure developing into far western KS will continue to approach overnight interacting with the boundary over central IL by morning. As a result...extensive high cloudiness over the area will eventually be replaced by low cloud and drizzle working its way northward Saturday morning. Fog may also develop overnight...especially along the boundary where winds are weakest...however extensive high cloudiness seems it may mitigate the radiational cooling needed to form fog so latest guidance continues to be non- aggressive on fog overnight. No significant updates planned at this time to afternoon forecast package. && .SHORT TERM...(This evening through Saturday) ISSUED AT 310 PM CST Fri Feb 10 2017 20z/2pm surface analysis shows 1031mb high anchored over the southeast CONUS...while a 997mb low tracks across northern Minnesota. The pressure gradient between these two features continues to provide brisk southerly winds across central Illinois this afternoon...with wind gusts in the 25-35mph range. As the pressure gradient gradually relaxes, winds will decrease to 10-15mph early this evening...then will drop to less than 10mph overnight. With diminishing winds and only high/thin cirrus overhead, the potential will exist for fog development overnight...particularly across the northern half of the KILX CWA where recent snow melt has added copious amounts of moisture to the boundary layer. Latest HRRR shows fog developing along/north of a Rushville to Danville line after midnight. With a frontal boundary settling southward into central Illinois, winds will become light across the entire area during the day Saturday. As additional moisture is advected northward across the boundary, low clouds and fog will become widespread through the afternoon. Forecast soundings indicate saturation from the surface only up to about 900mb. Given the shallow boundary layer moisture, think the chances for measurable precip are slim. As a result, will only mention low chance PoPs for showers during the afternoon. Main story will be the fog and drizzle...along with the warm temperatures. High temperatures will mainly be in the upper 40s and lower 50s...but will reach the upper 50s and lower 60s south of I-70 where southwesterly winds will persist the longest. .LONG TERM...(Saturday night through Friday) ISSUED AT 310 PM CST Fri Feb 10 2017 Low pressure will pass across Illinois Saturday evening triggering light rain. Very shallow moisture profiles might even support drizzle instead of rain at times depending on how much isentropic lift develops. Stronger lift would favor rain. The 12z models are in decent agreement that the low will track roughly along I-70, advancing into Indiana by midnight. The highest rain chances continue to be focused east of I-57 during the evening, with precip tapering off after midnight in the wake of the low. The low departure will signal the arrival of colder air under advancing high pressure, creating some non-diurnal temperature swings across southeast IL on Sunday. Morning temps south of I-72 look to continue to drop a few degrees after sunrise on Sunday, before beginning to rise again late morning into afternoon. Areas N of I-72 should see a typical hourly temperature pattern, with rising temps from sunrise into mid-afternoon. Despite the colder air, highs should still climb above normal, with low 40s north of Peoria and low 50s south of I-70. The remainder of the extended looks to be free of precipitation as the main weather maker in the southern stream drifts from the Four Corners region due eastward toward the Gulf states, instead of closer to Illinois. The northern stream system will pass north of Illinois into the Great Lakes, dragging a dry cold front/trough through Illinois on Tuesday. That push of colder air will drop temps to around normal for Tuesday night through Wednesday night. With the colder air in place on Wednesday, the 12z ECMWF continued its trend of extending Lake Effect precipitation southward toward Vermilion and Edgar counties. Have increase clouds a bit in that area, but left precip out of Wednesday for now. Gradual warming will prevail for the rest of the week, as southerly winds develop later on Thursday and continue on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 557 PM CST Fri Feb 10 2017 Southerly winds will diminish this evening as a boundary settles closer to the area from the north weakening pressure gradients over central IL. With the weakening surface winds...lingering swift WSW flow aloft will allow for a period of low level wind shear this evening...diminishing overnight as weaker winds associated with a pressure trough aloft approach. With the lighter winds moving in from the north and copious low level moisture...fog potential will develop overnight particularly at KPIA-KBMI. At this point...guidance suggests MVFR vsby. A low pressure system tracking toward southern IL from the central Plains will then bring copious low level moisture interacting with the boundary across central IL to bring IFR ceilings, drizzle, and fog after 12-17Z, particularly south of KPIA-KBMI. Winds at the surface will be fairly light and variable from late in the night through Saturday, but likely becoming predominantly E-NE toward the end of the forecast period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...Barnes LONG TERM...Shimon AVIATION...37
National Weather Service Jackson KY
1049 PM EST Fri Feb 10 2017 .UPDATE... Issued at 1049 PM EST FRI FEB 10 2017 The mixing continues, as even the mesonet at Quicksand has recovered sharply into the mid 50s. The latest satellite still shows plenty of thinness upstream, especially south of the Mountain Parkway, so will maintain the potential for the valleys to cool off, in some cases once again through the 06z time frame. UPDATE Issued at 859 PM EST FRI FEB 10 2017 South to southwest winds have kept things mixed in most locations, with even a few places at their high for the day right now, like the mesonet at Whitesburg, currently reporting 58 degrees. The mesonet at Quicksand has exceeded cool expectations, having dropped rapidly between 6 and 8 pm. They are currently reporting 37 degrees, with most other locations reporting anywhere from the upper 40s to mid 50s. The surface pressure gradient looks to slacken after 03z, and current satellite trends suggest still fairly thin cloud cover in place. As such, will hold onto the idea of decoupling, but just delaying it more until between 03 and 06z. Clouds will be on the increase between 06 and 09z, with readings likely leveling off or even coming up once again. The latest HRRR continues to support some potential light precipitation along and west of the I-75 corridor towards 12z, so will maintain the slight rain chances. Updates will be out shortly. UPDATE Issued at 653 PM EST FRI FEB 10 2017 The forecast is on track. Freshened up the hourly temperature drop off through early this evening, based on the latest trends in observations. Will have to see how well some of the valleys decouple, as several hours of partly cloudy to mostly clear skies look on tap and surface winds remain out of the south southwest. For now, think that temperatures in the lower 40s look reasonable for some of the cooler sites. Updates have been sent. && .SHORT TERM...(This evening through Saturday night) Issued at 325 PM EST FRI FEB 10 2017 A rather zonal pattern is in place from the Central to Eastern Conus. At the surface, high pressure is shifting to the east of the area while the pressure gradient has increased ahead of an area of low pressure over the Plains. Temperatures have moderated significantly since yesterday afternoon with most locations in the 40s to lower 50s at this time in the warm advection pattern. Dewpoints however have been slower to recover and are in the teens to lower 20s. Winds have been a bit on the gusty side with gusts as high as 15 to 20 mph. A shortwave trough is currently moving across Ontario and the Great Lakes region while another shortwave trough is moving across the Western Conus. The Great Lakes shortwave will pass by well north of the area tonight and into early on Saturday. Meanwhile, the northern portion of the trough now moving across the Western Conus is projected to quickly move across the Western US and reach the Plains late Saturday and into Saturday night. The surface high will continue to depart to the east and southeast of the area and move off into the Atlantic tonight. Meanwhile surface low pressure will gradually organize across the Plains tonight and into Saturday before tracking into the Mid MS Valley and lower OH Valley regions late Saturday and into Saturday night. Return moisture will increase across the area tonight as the high departs and ahead of the developing low pressure system over the Central Plains. The pressure gradient will also be strong enough to transport enough low level moisture into the area below 700 mb for threat of light showers starting very late tonight and into Saturday morning. The shower chances will persist through the day on Saturday with the highest chances in the west. Shower chances will be greater, however, on Saturday night as the surface low passes by to the northwest of the area and a cold front and upper level trough approach. Temperatures will be on the mild side tonight as the pressure gradient remains rather steep. However, some eastern valleys may experience a period of lighter winds in the evening and a breif decoupling. Some of the deeper valley temperatures were lowered below model guidance blends but not nearly as low as the Coop MOS. Low clouds will persist through the remainder of the period with even milder temperatures on Saturday and little diurnal range into Saturday night. .LONG TERM...(Sunday through Friday) Issued at 245 PM EST FRI FEB 10 2017 Models in decent agreement from Sunday into Tuesday. Looks like a cold front will dive south across the area on Sunday with good rain chances ahead of this boundary on Sunday. Temperatures will then plunge behind the front for the start of the new week. High pressure will bring moderating temperatures for the first part of next week as it traverses the region. The real complex part of the forecast comes Tuesday night through Wednesday evening as we may see the northern and southern stream start to interact with each other. The degree of interaction will determine exactly how the weather plays out for the middle of the week. The ECMWF has these two waves phasing completely over our region generating a surface low that will track to our southeast. This scenario would lead to high potential for accumulating snows over some portion of our area, especially southeast Kentucky. The GFS keeps these two systems separate with almost no phasing. That scenario would likely keep us mainly dry. With this said, had to include an extended period of pops from Tuesday night through Wednesday evening to account for a potential phased system. Will include a mention of snow in the HWO with the possibility of more phasing. Another cold shot will follow on Thursday and have undercut guidance significantly as highs will struggle to get much above the mid 30s on Thursday. Looks like we may start to warm again as we head into next weekend as the weather dries out again. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 653 PM EST FRI FEB 10 2017 Scattered mid and high level clouds will be seen through 06z, before ceilings gradually lower through dawn, as a low level jet ramps up across the Ohio Valley. Eventually, MVFR/IFR clouds will develop and continue through the day on Saturday, with some scattered light rain showers seen at times. Low level wind shear will be prevalent through around 12z, with southwest winds of between 5 and 10 kts at the surface continuing through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...JP LONG TERM...KAS AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
540 PM CST Fri Feb 10 2017 .SHORT TERM...(This evening through Saturday) Issued at 347 PM CST Fri Feb 10 2017 Main concern for the short term is the cold front dropping south in northern MN and the stratus behind it. This front will make it down to about the Iowa border by Saturday morning, where it will wash out. The HRRR shows this stratus spreading south through the night, though even if we don`t get these low clouds, we will have plenty of Pacific moisture streaming overhead through the night, so we will at least have plenty of mid/upper level cloudiness. The remnants of the front will then become a part of our one chance for precip over the next week Sat afternoon into Sat night. The Canadian/ECMWF show a band of precip developing to the north of this boundary during the day Saturday, with the ARW, NMM, and experimental HRRR showing a narrow band of precip developing in either northern IA or southern MN as well. The NAM/GFS both show issues with there being enough low level moisture to allow for precip, so we have small chance pops down there. Though it will be cooler in the wake of the cold front tomorrow, we`ll still see highs get into the upper 30s, so p-type with anything we see will be rain. .LONG TERM...(Saturday night through Friday) Issued at 347 PM CST Fri Feb 10 2017 The only chance for precip during the long term comes right out the gate Saturday night. It will also remain mild, save for a brief retreat in temperatures Wednesday thanks to a backdoor cold front coming in Tuesday night. The forcing for precip chances Saturday night will be driven by the wave currently coming onshore in Washington. This shortwave will be working across MN Saturday evening. The Canadian/ECMWF, which have precip Sat afternoon, build that precip northeast into western WI through the night, while the dry NAM/GFS remain dry. Given the disagreements, continued low chance pops into Saturday night. For p-type, have gone pretty simple, starting with rain and transitioning to snow through the night as temperatures cool. Like Saturday afternoon, QPF looks marginal, so any snowfall amounts would be nothing more than a dusting. For next week, there are no systems of much organization coming across the upper Midwest, with the week looking to be dry locally. Today, the GFS/ECMWF are both now showing a backdoor cold front coming west out of the Great Lakes Tuesday night, this looks to bring a brief pause in our thaw Wednesday, when temperatures look to retreat back closer to or even a little below normal. However, we`ve seen the models bounce around quite a bit in the last couple of days with how far west this front will make it mid-week, so our forecast is a bit warmer than what the 12z GFS/ECWMF would say. This cool down will be short lived as both the GFS and ECMWF show upper ridging building into central North America by the end of the week, with h5 heights building to in excess of 564dm in southern MN, so we`lllikely finish next week with highs topping 50 for parts southern MN once again. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 540 PM CST Fri Feb 10 2017 An east-west cold front across northern MN this evening will slip slowly south overnight. MVFR/IFR ceilings trail the front and these ceilings will arrive into central MN after 06z and approach the Twin Cities and western WI by daybreak Saturday. NAM 0.5 deg CPD`s show the ceilings then lifting back ENE during the morning and continuing in the afternoon at KRNH and KEAU. In addition, due to the influx of low level moisture today, some restriction to visibility is likely across central MN around daybreak with KAXN likely the recipient of the lowest values. WSW winds this evening 5-10 knots becoming N 5 knots or less overnight and then WNW 5 knots for Saturday afternoon. KMSP...Confidence not high on the IFR ceilings Saturday morning but the timing of the ceilings in the wake of a weak cold front during the morning where the best low level saturation is progged makes sense. Improving conditions for the afternoon as the low level winds back to the WSW pushing the low ceilings off to the east. /OUTLOOK FOR KMSP/ SUN...MVFR possible early. Wind NW 10 to 20 kts. MON...VFR. Wind SW 10 kts. TUE...VFR. Wind NW 10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...MPG LONG TERM...MPG AVIATION...RAH
Area Forecast Discussion
National Weather Service Norman OK
949 PM CST Fri Feb 10 2017 .UPDATE... Updated hourly temperature/dewpoint forecast through 14Z to blend with current observation trends. Otherwise, no significant changes were made to the forecast. && .DISCUSSION... Similar to last night, the NAM12 and HRRR indicate that the strongest winds will be along a northwest to southeast line from Woodward to Oklahoma City to Seminole. These areas are expected to stay the warmest tonight. Slightly cooler temperatures are expected across north central and southwest Oklahoma, where the winds will be lighter. Either way, it will be a seasonably warm night with low temperatures near average high temperatures for this time of year. The 11/00Z NAM still indicates record setting temperatures for tomorrow afternoon. The NAM is forecasting an 850 mb temperature of ~22C at Norman (OUN) for 00Z tomorrow evening. To put this in perspective, the record for the entire month of February (according to the SPC Sounding Climatology Page) is 21.9C. Mahale && .PREV DISCUSSION... /issued 504 PM CST Fri Feb 10 2017/ DISCUSSION... Please see the 00Z aviation discussion below. AVIATION... VFR will apply through the forecast period. Winds will remain around 15 to 20 kt before sunset, and then decrease to around 15 kt or less overnight. A few high clouds are expected. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 54 87 43 54 / 0 0 0 10 Hobart OK 51 89 42 54 / 0 0 0 10 Wichita Falls TX 54 90 46 59 / 0 0 0 10 Gage OK 50 89 37 50 / 0 0 0 10 Ponca City OK 51 84 41 53 / 0 0 0 10 Durant OK 59 83 52 62 / 0 0 10 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Red Flag Warning from 11 AM to 7 PM CST Saturday for OKZ004>030- 033>040-044-045. TX...Red Flag Warning from 11 AM to 7 PM CST Saturday for TXZ083>090. && $$ 10/03