Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/06/20


Area Forecast Discussion
National Weather Service Cheyenne WY
527 PM MDT Fri Jun 5 2020 .SHORT TERM...(This evening through Saturday) Issued at 224 PM MDT Fri Jun 5 2020 Current satellite imagery shows Cu developing along the Laramie Range with a few weak echos being returned to radar. Scattered showers will continue to develop later this afternoon and early evening. Biggest issue will be which areas remain capped through the afternoon. Latest SPC mesoanalysis shows 1000-1500 J/kg of MLCAPE cutting across Converse Co. through the southern Nebraksa Panhandle with 50 kts of effective shear over northern portions of the CWA. However, MLCIN still needs to be overcome for storm development. High-res models have been consistent to initiate a few storms along the South Laramie Range that are short-lived. One spot to watch tonight is up near Bill, WY where HRRR and NAMNest runs have been initiating a stronger storm. A few attempts at deep moist convection have been ongoing across Natrona Co. over the last hour. Would expect more successful attempts over the next two hours as more favorable instability is located farther east along with impressive turning of winds with height supporting 0-3 km SRH around 200 m2/s2. Severe threat is possible tonight, but should remain fairly isolated. The upper level cutoff low off off the California Coast will finally begin to propagate northeastward this evening. Large scale upper level support will move over the area by early Saturday morning with showers possible. Convective activity looks to begin early in the afternoon Saturday as the vort max moves through the Rockies. One area of concern will be the instability available for strong convective updrafts to develop. Development of initial shower activity could limit late morning insolation, especially along the Laramie Range. Currently, models are hinting at a short- lived period from 18-21z of 2500 J/kg MLCAPE over the Nebraska Panhandle. A cap looks to remain in place through the day, however upper level support should be strong enough to aid in initially elevated convection across this area. Strong upper level winds will support fast storm motions and the potential for strong TSTM wind gusts with 700 mb winds exceeding 50 kts. Shear profiles are fairly unidirectional with effective shear 60-70 kts. Despite limited hodograph curvature, elongated shear profiles still suggest noteworthy 0-1 km helicity values. High-res guidance has been suggesting primarily linear storm mode with discrete cells possible farther northeast and multiple waves of storms passing through with leading shortwave energy ahead of the main vort max. Main threats Saturday will be strong wind gusts to 60 MPH likely with storms and severe hail east of the Laramie Range. Largest hail potential will remain with the greater instability over western Nebraksa. Possibility of a tornado is still there, but remains low. SPC has highlighted areas within the CWA east of the Laramie Range with a Slight Risk of Severe Thunderstorms while an Enhanced Risk sits over the northern Nebraska Panhandle extending to the northeast of the CWA in South Dakota. .LONG TERM...(Saturday night through Friday) Issued at 251 AM MDT Fri Jun 5 2020 Warm and mainly dry conditions expected Sunday ahead of the upper trough over the western CONUS. A few showers or storms possible out west in the afternoon as a cold front edges east during the day. Much cooler and unsettled conditions set in for Monday and Tuesday as the upper trough moves across the region with showers and a few storms especially late Monday. Dry and warmer Weds and Thursday as an upper ridge amplifies over the Rocky Mountains. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 523 PM MDT Fri Jun 5 2020 VFR flight conditions expected through 06Z, despite VCSH causing brief, erratic wind gusts near vicinity of terminals. Wind gusts of 20-30 knots are likely due to the nearby rain showers for the WY terminal sites. CDR could also stay gusty past 06Z in addition to the WY terminals mentioned before. AIA, BFF, and SNY should see winds approximately 15 knots or less through 6Z. The approaching weather system from the southwest will begin to increase chances of rain from west to east after 6Z. This will be mentioned in the next update around 0530Z. && .FIRE WEATHER... Issued at 224 PM MDT Fri Jun 5 2020 Afternoon temperatures have reached the 80s for most locations with relative humidity dropping into the low 20s and teens along and west of the Laramie Range. Wind gusts 20-25 MPH bring conditions to near Red Flag Criteria, but critical fuels are not ready. Widespread wetting rain is expected Saturday with thunderstorms and strong winds. Cooler temperatures are on the way early next week, but relative humidity in the southern Nebraska Panhandle will drop into the teens before then on Sunday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MB LONG TERM...CLH AVIATION...BW FIRE WEATHER...MB
Area Forecast Discussion
National Weather Service Des Moines IA
639 PM CDT Fri Jun 5 2020 .DISCUSSION.../Tonight through Friday/ Issued at 258 PM CDT Fri Jun 5 2020 Synoptic Overview: Short-wave trough with 70 kt H5 jet streak is moving from the upper Midwest into the northern Great Lakes Region as of this morning. Weak, broad ridging has been occurring over the Northern Rockies, and the axis is sliding eastward toward the northern Plains with another trough off the NW Pacific Coast. Surface low pressure is also pushing eastward, with surface high pressure over the northern Plains strengthening with the AVA under the ridge setup. This has been slowly pushing a boundary southeast across the Missouri River Valley today. Today: Strong WAA over the Plains will result in amplification of the H5 ridge that is shifting eastward across the central and north central CONUS. This afternoon, that will result in mid-level flow briefly being northwesterly. On the backside of the surface low over the Great Lakes and with surface high pressure over the northern Plains, near surface flow will also be generally northwesterly. As a result, this will push the boundary southeastward throughout this afternoon. Since 12z, CAM guidance has backed away from placing light showers and weak thunderstorms in southwest Iowa later this afternoon and early evening. Exploring the soundings of the HRRR and RAP, the solutions indicate rather dry air between 850 mb and 650 mb, which certainly would suppress shower activity. However, lapse rates in the low to mid levels are somewhat steep, and with clouds clearing and plenty of insolation will likely be realized. This may be just enough for a few parcels to rise and result in a few weak showers. Thus, have slightly decreased POPs for later this afternoon and evening, but have not gone completely dry. As for temperatures this afternoon, expecting a decent recovery as clouds clear in plenty of time for peak heating. Northern and northwest Iowa will remain cooler on the north side of the boundary, with temperatures in the lower 80s. Central and southern Iowa will reach the mid to upper 80s. South of the boundary, with dewpoints in the upper 60s to lower 70s, heat index values will be in the lower 90s. This will make for an overall muggy day across central and southern Iowa. Saturday and Sunday: Saturday the synoptic pattern will begin to get interesting with the northward progression of what is now Tropical Depression Cristobal, moving into the open Gulf of Mexico off the Yucatan Peninsula. The axis of the amplified H5 ridge will attempt to slide east, being set in motion by a negatively titled short-wave trough in the southwest CONUS and an Aleutian low centered off the NW Pacific Coast. As surface high pressure slides eastward with the ridge axis advancement, low-level flow turns southerly which will advect a warm-moist airmass back into the upper Midwest immediately after seeing the passage of the weak cold front from Friday afternoon. Afternoon high temperatures will recover back into the upper 80s for western and southern portions of the forecast area. Rain shower and thunderstorm chances Saturday will be highly dependent on the role of Cristobal has in blocking the eastward advancement of the ridge axis, as the short-wave trough quickly ejects northeastward into the Plains with a 70 kt H5 jet streak. This will provide a shot of CVA on the backside of the ridge and tries to force sudden height falls over the upper Midwest. However, 12z GFS/NAM//ECMWF guidance currently depicts Cristobal halting any eastward progress of the mid-latitude flow. Thus, this would keep heights steady Saturday while forcing the quick ejecting short-wave trough into the Canadian Prairie Provinces. This will certainly lead to some kind of perturbation in the mid-level flow across the upper Midwest, but 12z cycles of most guidance now keeps the better forcing for precipitation in the eastern Dakotas and western Minnesota. The GFS is only the model that attempts to have any kind of light rain shower activity in northern Iowa. Most ensembles members remain dry Saturday, thus will keep POPs and rain showers chances extremely limited across northern Iowa. Sunday, the large scale pattern remains roughly the same as Cristobal continues to track inland. The short-wave trough axis continues to swing northeastward into Canada. Another shot of weak CVA may reach the northern extent of the forecast area, which could force out a light shower. Thus have a brief period of low POPs north of U.S. Hwy. 18 going for Sunday. As with any extratropical cyclone, changes in the track will greatly influence these limited precipitation chances. The main weather story for the rest of the forecast area on Sunday will be brisk winds, as surface-cyclone associated with the short- wave tracks through the central Plains and increases the strength of the pressure gradient. At this time, expecting wind gusts to remain well below wind headline criteria. Extended Forecast: Warmer temperatures will continue through Monday while the H5 ridge remains in place across the upper Midwest and southerly flow continues to move in. Cristobal (or what is left of it) will bring rain shower and thunderstorm chances Tuesday through Wednesday. The 12z cycle of the GFS and ECMWF are actually in decent agreement about brining widespread rainfall to Iowa with this cyclone. The GFS is just a tad faster, but overall both models track the center of the cyclone along roughly the same track. Expect thick cloud cover Tuesday through Wednesday, which accompanied by heavy rain showers will help to reduce temperatures across the state thorugh the middle and end of the next work week. QPF will need to be monitored closely with rainfall associated with Cristobal. While several areas will be able to handle a decent amount of rainfall, other areas may begin to see flooding issues, and will also need to be concerned about river levels. As QPF becomes more certain, will have further discussions about hydrology concerns across the state. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 639 PM CDT Fri Jun 5 2020 A warm front will be located to the south and west of Iowa during the day Saturday. Precip may form in these areas but for Iowa, VFR conditions will prevail. Afternoon mixing will yield wind gusts to between 15 and 20 kts mainly across northern TAF locations. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Krull AVIATION...FAB
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
957 PM EDT Fri Jun 5 2020 .UPDATE... Waning instability coupled with intrusion of dry air and subsidence behind the cold frontal boundary will end all rain chances over the next hour, with the exception of portions of the northern Thumb where an area of residual moisture holds on. Any shower activity observed will be light in nature with no thunderstorm activity expected. This will lead into a mostly clear and calm night with a secondary weak cold front expected to pass through SE MI by the late morning/early afternoon hours. Dry air and weak frontal forcing will preclude any rain chances tied to secondary front. && .PREV DISCUSSION... Issued at 731 PM EDT Fri Jun 5 2020 AVIATION... Ongoing passage of a cold front combined with a subtle low-level boundary located just north of the Metro terminals have produced weak isolated showers confined mainly just north of the Metro area, with secondary showers wedged between KMBS to KFNT. This subtle forcing combined with a slight uptick in instability will continue to produce a low-end rain shower or short-lived thunderstorm through 01Z. Given the isolated coverage and low-confidence for development, rain and thunderstorms will be left out of this TAF issuance with the exception of KDET, where two convective cells reside. Broadscale subsidence has and will continue to fill in behind the front which will effectively end all rain chances and will produce VFR cigs through the overnight hours. Gradually wind shift from west to northwest will take place tonight and overnight, with northwesterly flow expected to hold through the bulk of TAF issuance. For DTW... Low-end chance for showers or an isolated thunderstorm through 01Z, tied to a subtle northerly boundary, otherwise, dry weather and VFR cigs overnight. DTW THRESHOLD PROBABILITIES... * Low for an isolated thunderstorm through 01Z PREV DISCUSSION... Issued at 526 PM EDT Fri Jun 5 2020 DISCUSSION... Forecast reasoning provided in the Update Discussion Issued at 1103 AM EDT regarding the severe weather potential this afternoon and early evening hours remains valid. Low level thetaE warm sector will remain in place across all of Southeast Michigan through 00Z as 6 hr 1000-500mb geopotential height falls remain centered over the area. Depth of antecedent dry air with rapid onset to lower level thetae continues to wreak havoc in the forecast soundings. The latest HRRR solutions are somewhat puzzling not giving any credit to the lower to middle 60 dewpoints that are surging across western Lower Michigan in tow of this initial shower and thunderstorm activity. The potential still exists for an isolated strong to possibly severe wind gust with deep convection through 35.0-40.0 kft agl. However, relatively slow cell movement of 25 mph and weak environmental wind field less than 25 knots through 10.0 kft agl will be a significant negative on convective environment/potential. Latest CAM signal suggests thunderstorm potential through approximately 23Z. Low level thetae scours out rapidly 03-06Z as a cold front pushes across the area. Low to midlevel wind trajectories will then transition to anticyclonic, supporting very efficient isentropic downglide on the 310-307Ke surfaces. Forecast soundings do show a clear signal for aggressive subsidence centered at 650mb by 06Z tonight. Strong support within the models for surface based ridging this weekend. Models showing very strong stability from 3.0 through 15.0 kft agl. Very quiet and ideal summer weather for Southeast Michigan. Highs this weekend are expected to reach middle 70s to around 80 degrees both Saturday and Sunday. Little cloud cover is anticipated. High amplitude upper level ridge is then forecasted to develop over the Central Great Lakes for the beginning of next week. Models indicate H5 heights potential exceeding 588 dam. Current forecast information suggests highs reaching the low 90s will be possible on Tuesday. Main item to be monitoring will be the forecast trends regarding Cristobal remnants as its forecasted to lift due northward into the Midwest. Uncertainty exists with timing of interaction between tropical moisture and strong upper level trough/PV over western United States. Important, because eventual track of Cristobal will bring with it a heavy rainfall and flooding risk. MARINE... Areas of gusty showers and thunderstorms are advancing across Lake Erie this evening which may lead to locally higher waves. A cold front moves through late this evening bringing about additional showers and thunderstorms followed by northwesterly flow. Wind speeds will increase on Saturday as the surface gradient strengthens due to stronger high pressure building to the northwest and a deepening low over the Northeast. High pressure over northern Ontario shifts eastward on Sunday with a secondary high over northern Lake Huron causing winds to veer toward the northeast drawing slightly cooler and drier air into the central Great Lakes. A warming trend begins on Monday as high pressure influence keeps conditions dry with lighter winds veering southeasterly. The remnants of TS Cristobal arrive mid-week presenting timing and precipitation uncertainty. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ UPDATE.......AM AVIATION.....AM DISCUSSION...CB MARINE.......KK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service North Platte NE
628 PM CDT Fri Jun 5 2020 .SHORT TERM...(This evening through Saturday night) Issued at 301 PM CDT Fri Jun 5 2020 A few of the CAMs show isolated storm development this evening across the ern Panhandle. Winds aloft are strong with 35 kts at h500mb and CAPE around 2000J/KG will be in place. Storm development across the Front range and Laramie range should be underway by 21z but as the storms move east toward wrn Nebraska, they will encounter increasing amounts of warm air at h700mb effectively capping development. If the cap is weaker than predicted by the models, isolated strong or perhaps severe storm development is possible as suggested by the HRRR and NSSL WRFARF models. Wind would appear to be the primary hazard given large delta-T-TD spread in the lower levels of the model soundings. A strong warm front with low level winds of 40 to 65 kts lifts through wrn and ncntl Nebraska tonight. These winds will continue through Saturday and Saturday night. The RAP model suggested an isolated thunderstorm chance as this occurs late tonight and Saturday morning. It is the only model to show this and the forecast is dry tonight. An area of morning stratus should develop across the Sandhills with burn-off by 17z. Severe storm development appears likely across wrn Nebraska from about 21z Saturday afternoon through 06z Saturday night. One or more clusters of storms should develop over the Cheyenne divide and nern Colo/Sern WY which will move rapidly northeast through the Panhandle and wrn Nebraska. The HRRR and NAMnest models show a forward storm motion of 50 to 60 mph. This is likely a result of the strong winds below 700mb and an approaching 50-70kt h500mb jet. The NAM is also showing 0-1km layer helicity values increasing to 500 to 1000 m2/s2 Saturday evening along a stalled Pacific front stretching north and south across all of wrn Nebraska. This is likely the reason SPC posted a 2% TOR prob across nrn Nebraska. SPC suggests bows and bow segments lifting rapidly northeast will pose a significant wind damage threat. Given the steepening lapse rates from an approaching upper level trof and very strong warm air advection progged up the Colorado plains, very large hail is possible also. .LONG TERM...(Sunday through Friday) Issued at 301 PM CDT Fri Jun 5 2020 Sfc low pressure will lift through Nebraska Sunday and the latest model blend suggests a lull in storm development. This likely the result of the best focus shifting north into the Dakotas and a strong cap across Nebraska. The NAMnest suggests storms could still fire north and south near or between highways 83 and 61, but it is the only model showing this. The forecast follows the model consensus which is dry. The model consensus is in good agreement for storm development Monday evening across ncntl Nebraska and a portion of southwest Nebraska. The models have been consistent with this feature for a couple of days now. A Pacific cold front aligned north and south across ncntl Nebraska will be the focus for development, winds aloft are strong at 50-65kt and MLCAPE should be around 3000J/KG. The Pacific front should be east of ncntl Nebraska Tuesday and cooler temperatures are in place through Friday. Shower and thunderstorm chances continue Tuesday associated with cold air aloft. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 628 PM CDT Fri Jun 5 2020 Thunderstorms and winds are the primary aviation weather threats for western and north central Nebraska. Isolated storms are possible in the panhandle and far northern Neb. late tonight into Saturday morning. Otherwise, VFR will continue with low level wind shear affecting most terminals overnight. Winds turn more southerly for Saturday and strengthening with gusts 30+ kts in the afternoon. Storm chances also increase late afternoon, starting with the western terminals. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
624 PM CDT Fri Jun 5 2020 .SHORT TERM... 254 PM CDT Through Saturday night... Isolated severe risk through early evening: The convective potential this afternoon-evening continues to be uncertain, and if thunderstorms occur, coverage is expected to be low/isolated to perhaps widely scattered. There remains a conditional strong to severe thunderstorm risk, covered well by SPC`s Marginal (level 1) Risk. Expansive convective blow-off cirrus has been shrouding the region, though temperatures have been able to warm into the mid to upper 80s. A recent aircraft sounding out of MDW indicates a lingering cap to surface based convection there, though SPC/RAP Mesoanalysis suggests cap is eroding from the northwest. Lake breeze boundary is stalled out from the Cook County North Shore area to the eastern portion of Lake County. Potential scenario for convective initiation (CI) this afternoon into the evening is similar to earlier posted update. It will be tied to low level frontal convergence, enhanced by lake breeze convergence, likely with an emphasis on the lake breeze/cold front inflection. Visible satellite imagery shows most congested cumulus near the lake breeze in southeast Wisconsin and far northeast Illinois and there was an attempted shower near Kenosha around 2pm. Farther upstream, cumulus field not all that impressive looking and winds have already turned northwesterly in the northwest portion of the CWA with a pre-frontal wind shift. It appears true frontal boundary stretches from near the MS River to southwest Wisconsin. MLCAPE values may top out in the 1500-2500 j/kg range as suggested by recent mesoanalysis, which is more than sufficient given northwesterly deep layer shear of 30-40 kt. Biggest question mark continues to be the coverage of thunderstorms, if any, ahead of the front. 12z sounding from Aberdeen SD sampled exceedingly dry air in the 700-500 mb layer and model forecasts suggest this is in the process of being advected overhead. Lack of large scale mid and upper level forcing and relying solely on frontal convergence also adds to the uncertainty. The mid-level dry air entrainment could be tough for incipient updrafts to overcome and mature into thunderstorms, which may have been the case with attempted CI over southeast WI. Dew points have also mixed out a bit over portions of the Chicago metro, though this is not uniformly the case. It is apparent that some of the more aggressive 12z CAM solutions, namely the 3km NAMNest and NSSL WRF, will be overdone with dew points along the front, which helps explain their more concerning depiction. The above limiting factors in mind, am still concerned that a couple storms may be able to overcome the dry air entrainment, particularly in the vicinity of the lake breeze/cold front inflection through early evening where convergence will be maximized. *If* a storm or two should tap into the favorable parameter space on the instability, shear, mid-level lapse rate spectrum, there is a concern for an isolated robust severe storm. Main threats if a storm does become severe would be damaging downburst winds given steep low level lapse rates and plenty of DCAPE from aforementioned dry air aloft. In addition, with favorable shear vector orientation to cold front, any supercells would also have a large hail threat. Recent HRRR runs have been steadfast in little/no development with the front, with the aforementioned WRF based guidance on the other end of the spectrum. The latest observational trends seem to point toward coverage being low at most, but still don`t want rule out the possibility of a thunderstorm or two getting going. Will need to monitor satellite and radar trends closely. With all the uncertainty described, kept PoPs capped at 20% to 30%. The storm motions should be 30-40 mph off to the southeast, so while any thunderstorm would certainly produce brief heavy downpours, not expecting a flash flood threat. If convection occurs, it will sag south and gradually dissipate with diurnal stabilization by the mid to late evening near and south of the Kankakee River. Timing for isolated severe risk could be as early as 3-4pm in the far north to 8-9pm south of I-80. Skies will clear out tonight behind the front as the cooler and drier/less humid air mass advects in for the weekend. After a relatively cool start to the day, Saturday will be a pleasant early summer day with plenty of sunshine despite 500 mb heights from mid-level ridging over the central CONUS typically being supportive of warmer readings. This will be due to expansive high pressure taking on backdoor characteristics as is centers over the Great Lakes. Dew points are likely to drop to the 40s to around 50 Saturday afternoon, which will make it comfortable for outdoor activities. Highs will top out in the lower to mid 80s well inland (warmest south) and 70s downwind of Lake Michigan, with mid to upper 60s lakeside due to steady northeast winds. It appears that the magnitude of the northerly winds will be just shy of producing waves more concerning from a dangerous waves and currents perspective at the beach. Saturday night will feature lows in the 50s area wide, and can`t rule out an isolated upper 40s reading in far northern Illinois. Castro && .LONG TERM... 303 PM CDT Sunday through Friday... Sunday through Monday night: The southwest extent of high pressure drifting across the northern Great Lakes will remain across the area during this time as a pronounced mid/upper ridge builds eastward. With 850 hPa temps surging into the 20-22C range Sunday night into Monday, afternoon highs Monday are expected to reach the low 90s for all but the immediate lakeshore of northeast Illinois. With dewpoints in the upper 50s and low 60s under a decent amount of sunshine, some localized readings tapping into the mid 90s cannot be ruled out. With the less humid conditions, heat index values should remain capped at values near the air temperature. Tuesday through Wednesday: Focus remains on local impacts from Tropical Storm Cristobal currently drifting north off the Yucatan Peninsula. Atmospheric Rex blocking from the aforementioned mid/upper ridge over the area Sunday into Monday creates some forecast challenges with regards to Crisotbal`s movement through mid- week, but the overall forecast is for a broad and deep trough over the western CONUS this weekend to nudge the ridge eastward and pick up Cristobal`s remnants on Tuesday. Guidance has been fairly consistent on this overall evolution, though placement and timing have varied enough due to phasing issues to preclude too much specificity in the forecast at this time. Consensus guidance brings the remnants northward just west of the Mississippi River through Tuesday morning before a northeast shift across the western Great Lakes Tuesday night. With it will come a tropical air mass with PWATs in excess of 2" and potentially strong winds in response to an anomalously deep surface low. While current indications are for the heaviest associated rains to remain just west of the CWA late Tuesday afternoon into Tuesday night, the CWA is well within the ensemble envelope of solutions to potentially fall within the axis of heaviest rain. Those with forecast sensitive interests Tuesday into Wednesday should continue to monitor the latest forecast through the weekend. Thursday through Friday: The western trough will deamplify to some extent while gradually lifting northeast into eastern Canada during this time. Most of this period should be dry with the exception of scattered precip along a potential cold front dropping south into the area on Friday. Kluber && .AVIATION... For the 00Z TAFs... 624 PM...Only forecast concern this period are the winds. There remains a small chance for an isolated thunderstorm this evening ahead of a cold front moving into northern IL. Nothing has developed so far and much of the short term guidance keeps the area dry this evening and no precip mention with this forecast. Winds are slowly turning northwesterly across northern IL and will likely become more northerly this evening...possibly turning to the north/northeast at ord/mdw but confidence is low. Winds should settle back on a light north/northwest direction overnight and winds will then turn northeasterly Saturday morning. Speeds should increase into the 10-12kt range and its possible some gusts into the upper teen kt range may develop late morning into the afternoon. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSChicago www.twitter.com/NWSChicago www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Little Rock AR
238 PM CDT Fri Jun 5 2020 .Short Term...Tonight thru Sunday... Remnant MCS drifted out of MO this afternoon and started to intensify as it moved to the southeast. The vast majority of this ended up east of the LZK forecast area, but one storm became strong enough to warrant the issuance of a warning. The area remains on the eastern edge of an upper level ridge. There is a significant amount of mid-level instability in place across the area with relatively little CIN in place. Wind shear is minimal. The dynamics of the ridge seem to be keeping most of the storms over the eastern portions of the state for the time being. The short term models have been all over the place in regards to how to handle the situation today and tonight. NAMNest and WRF models have been much more prolific with the convection, taking it well into the western portions of the state. HRRR model families have been more conservative, and while far from perfect, have been closer to the current situation. Models show the potential for further development mainly across the southeast quarter of the state, and I have gone with this trend. The potential for severe wind gusts certainly remains thru tonight. Ridging will continue across the area thru the period, and daily max temps will remain in the 90`s with dewpoints generally in the 70`s. && .Extended Term...Sunday Night thru Friday... The main story during the extended period forecast will be the arrival of Tropical Depression Cristobal. The tropical system is expected to move into the Gulf of Mexico this evening, and strengthen into a Tropical Storm as it approaches the United States. Late this weekend and into early next week, Cristobal is expected to move through portions of Louisiana, Mississippi, and Arkansas. Although Cristobal should weaken as it moves through Arkansas, much of the state will see widespread rainfall Monday through Tuesday night. Through this period, much of the central and eastern sections of the state could see between 3 and 5 inches of rain, with lesser amounts around 2 to 3 inches across western portions of the state. This will likely change as we proceed through the weekend and into early portions of the coming week, as any changes to the strength or path of the storm could alter the forecast. Strong and gusty winds may also be possible, especially across the southern portions of the state. Remnants of the storm will likely merge with troughing across the Plains regions by mid week, allowing a storm system approaching from the west to push through the Natural State. An associated surface cold front will also swing through the state, and help clear out rain chances on Wednesday and Thursday. Behind this feature, high pressure will return and help keep conditions dry. Conditions will be warm and humid, but cloud cover and rainfall from Cristobal, and the passage of a cold front, will help keep temperatures more mild than what we`ve recently seen. In fact, for most of the period, temperatures should be near normal values for this time of year. && .PRELIMINARY POINT TEMPS/POPS... Batesville AR 73 92 72 92 / 20 10 0 0 Camden AR 72 94 73 94 / 20 30 0 10 Harrison AR 70 91 70 89 / 10 20 0 0 Hot Springs AR 73 93 72 93 / 20 20 0 0 Little Rock AR 74 93 74 93 / 30 20 0 0 Monticello AR 73 92 74 92 / 40 30 0 10 Mount Ida AR 71 92 70 92 / 10 30 0 0 Mountain Home AR 71 92 71 91 / 20 10 0 0 Newport AR 71 92 75 94 / 20 20 0 0 Pine Bluff AR 73 92 73 92 / 30 20 0 10 Russellville AR 72 94 73 93 / 20 20 0 0 Searcy AR 72 92 73 93 / 30 10 0 0 Stuttgart AR 74 92 74 93 / 30 20 0 0 && .LZK Watches/Warnings/Advisories...NONE. && $$ Short Term...53 / Extended Term...69
Area Forecast Discussion
National Weather Service Miami FL
853 PM EDT Fri Jun 5 2020 .Update... Models have backed off on chances of showers and thunderstorms tonight, which has been the case this evening. Even so, there is still a chance for some to develop periodically, especially along the coastal areas, where some coastal convergence may occur. With a tropical system even having a minor influence, also can not rule out some of the storms obtaining strong thunderstorm characteristics, such as rotation or funnel clouds. && .Prev Discussion... /issued 728 PM EDT Fri Jun 5 2020/ Aviation... A relatively quiet spell is expected overnight, with some showers and thunderstorms still possible across the Gulf and West Coast. Scattered to widespread showers and thunderstorms are expected to develop across the area again tomorrow, with gusty winds, lightning, funnel clouds, heavy rain all possible. Mostly VFR conditions are expected outside of convection. Prev Discussion... /issued 350 PM EDT Fri Jun 5 2020/ Short Term... Today through tonight... Previous mesoscale discussion still valid through 22z... While highly uncertain, a localized conditional risk of a couple strong to locally severe thunderstorms could arise across portions of South Florida beginning early this afternoon and lasting into the late afternoon hours. This conditional risk appears to be greatest across the southern interior portions of South Florida early this afternoon, becoming focused over the Lake Okeechobee/interior areas later this afternoon. The primary concern with any of the stronger storms that develop this afternoon will be locally heavy rainfall -- which may lead to urban flooding, isolated strong to locally severe convective wind gusts, and frequent lightning. Important Note - An additional conditional risk of a few strong to locally severe storms may arise later this evening into the overnight hours. This threat may be greatest across the Gulf Coast of South Florida, though there is plenty of uncertainty regarding this threat at this time. Please keep up with the evolving forecast. In the low-levels, South Florida is under the influence of the western periphery of an Atlantic subtropical high, allowing for deep southeasterly flow up to near 800 mb. Rich moisture advection is quite evident in the low-levels along this southeasterly flow, acting to keep dew points in the low to mid 70s across the eastern portions of South Florida. This rich low-level moisture will likely continue to spread across South Florida from the Atlantic Coast towards the Gulf Coast, acting to strengthen low-level buoyancy. In addition, brief cloud clearing/thinning is evident across the southern and interior portions of South Florida from GOES-16 visible and water vapor imagery loops. This is also acting to strengthen surface-based instability by locally steepening 0-3 km lapse rates across the southern interior and western portions of South Florida, where horizontal convective rolls and agitated cumulus fields are currently evident. In the upper-levels, strengthening southwesterly flow in association with Tropical Depression Cristobal and an upper-level trough over the northern Gulf of Mexico is providing differential divergence across the region, leading to weak, albeit some synoptic ascent. This synoptic ascent may act to enhance/focus mesoscale convergence/ascent this afternoon along differential heating boundaries and horizontal convective rolls. As Tropical Depression Cristobal continues northward today, deep layer flow/shear will gradually strengthen across South Florida. This shear enhancement should first be realized across the Gulf Coast of South Florida later this afternoon into the evening hours when a southerly low- level jet may develop. While the flow/shear should remain relatively weak across South Florida during afternoon convection today, deep rich moisture combined with modestly steep mid-level lapse rates near 6.8 C/km and steepening low-level lapse rates may allow for a few strong convective wind gusts, with a highly conditional risk of a damaging wind gust. This threat may be enhanced by precipitation loading and modest updraft parcel accelerations in the low to mid-levels where mesoscale ascent becomes locally maximized. While there are some notable limiting factors for the development of a few strong to locally severe storms this afternoon (including lacking deep-layer flow/shear which will limit updraft separation and weak synoptic forcing for ascent), a conditional risk does appear to be present at this time. Please keep up with the latest forecast information from NWS Miami as the aforementioned threats/convective hazards will likely evolve with time. After 22z... After the initial convection moves to the north this evening, models are indicating a brief respite from active weather. However, by around 03/04z the HRRR is showing an extreme outer band of Cristobal may work its way into the area, especially the Gulf waters and the western half of the area. There appears to be a weak boundary somewhere north of the lake region, which may act to enhance some convective coverage tomorrow in the Lake region, although the entire area may see showers and storms through the day. Long Term... Saturday night through Thursday night... There is high uncertainty in the forecast after Saturday night. As Cristobal moves further north, away from the area, there is some uncertainty as to where an extreme outer band may set up. The GFS has a more distinct band, but keeps it offshore. The ECMWF looks to be trying to establish the out band, but is being affected by the lingering boundary. Either way, the best chances for rain Saturday night look to be off the Gulf coast. However, there is still too much uncertainty and there is a chance of showers and a slight chance of a thunderstorm through the night. For Sunday, while Cristobal should be getting ready to make landfall somewhere along the Central Gulf coast, the boundary over Central Florida keeps moisture and convection in the forecast, with the best chances in the Lake region, but again, can occur anywhere across South Florida through Sunday night, into Monday. Monday night should see improving conditions, although there is still a slight chance of showers through the night. By Tuesday, high pressure tries to build to the northeast, bringing the easterly flow back to the area, with ample moisture to keep periods of showers and thunderstorms through the entire week, with quieter period during the overnight hours. With the easterly flow, the Gulf coast and western interior will have the best chances for showers and storms each day, although they can not be ruled out for the east coast of eastern interior areas as well. Marine... A rather tight pressure gradient across South Florida between high pressure NE of the Bahamas and TS Cristobal will continue the moderate and gusty SE to S wind across the local waters through Sunday. The Gulf of Mexico waters will be at marginal small craft advisory levels as winds approach 20 knots and seas build due to wave energy/swells from Cristobal. The Atlantic waters will likely stay at cautionary wind/sea levels. Periodic bands or even squally- type of showers and thunderstorms with affect the Gulf waters this weekend, with more scattered showers/isolated thunderstorms over the Atlantic. TS Cristobal is forecast to make landfall along the north- central Gulf coast on Sunday, then move inland near the Mississippi Valley region early next week. High pressure over the Atlantic will build closer to Florida early next week. As a result, the pressure gradient is expected to relax, leading to overall lower wind and seas. Periods of showers and thunderstorms can still be expected over most of the local waters for the early to middle part of the next week. Beach Forecast... The breezy SE winds will keep a high risk of rip currents at the Atlantic beaches for most of the weekend. The rip current risk will also increase at the Gulf beaches beginning Saturday, and potentially to high risk levels on Sunday as wave energy from distant TS Cristobal should bring small to moderate swells to the surf zone. The wave energy and swells will also cause minor coastal flooding along portions of the Collier County coast this weekend, primarily around the times of high tide which will be during the afternoon hours, with a lower chance during the overnight time frame. && .Preliminary Point Temps/PoPs... West Palm Beach 76 86 78 87 / 30 50 40 60 Fort Lauderdale 78 86 80 87 / 30 40 40 50 Miami 78 87 79 88 / 30 40 40 50 Naples 74 87 77 87 / 30 50 50 60 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...Flood Watch through Saturday evening for FLZ063-066>075-168- 172>174. High Rip Current Risk through Saturday evening for FLZ168-172- 173. AM...None. GM...None. && Update...13
Area Forecast Discussion
National Weather Service Mobile AL
909 PM CDT Fri Jun 5 2020 .NEAR TERM /Now Through Saturday night/...A longwave ridge over the central states advances slowly eastward towards the western Great Lakes to the mid Mississippi River valley through Saturday night. The upper ridge also meanwhile begins to build into the extreme southeast states, gradually eroding an upper level weakness currently in place over the north central Gulf coast region. This transition in the upper level pattern over the region still looks set to play an important role in steering Tropical Storm Cristobal in a northerly direction across the central Gulf to approximately 100 miles south of the coast of southeast Louisiana by 12Z Sunday. Currently, a weakening Mesoscale Convective System over central Mississippi/Alabama has sent a decelerating outflow boundary into the interior portion of the forecast area. The outflow boundary continues slowly further southward into the forecast area overnight with showers and storms along the boundary gradually diminishing. Given the weakening trends seen in satellite and radar data, severe storm development is not expected with this feature. As Cristobal advances northward, easterly winds on Saturday increase to 10-20 mph, with the higher values near the coast, and similar values continue into Saturday night. Deep layer moisture steadily increases through the period, with precipitable water values of 1.5-1.8 inches increasing to 1.8-2.4 inches by Saturday night. Expect mainly scattered showers and storms to develop across the area on Saturday, then coverage increases over the southern portion of the area Saturday night as Cristobal approaches. A Tropical Storm Warning remains in effect for coastal Alabama to along the western Florida panhandle coast. A high risk of rip currents remains in effect, and a high surf warning and coastal flood advisory are in effect beginning Saturday afternoon. Lows tonight and Saturday night range from the lower 70s inland to the mid 70s at the coast, and highs on Saturday will be in the mid to upper 80s. /29 && .PREV DISCUSSION... /issued 654 PM CDT Fri Jun 5 2020/ AVIATION... 00Z issuance...Scattered showers and storms have developed over southeast Mississippi as well as over portions of coastal and south-central Alabama. Meanwhile, a line of showers and storms is moving southward over central Mississippi and central Alabama. Therefore, showers and thunderstorms will continue this evening. Kept mention of storms for BFM and MOB to account for this. Not expecting much activity around PNS. Any showers and storms are then expected to decrease overnight. With the advancement of Tropical Storm Cristobal northward towards the Gulf coast, showers and storm chances will increase Saturday morning and through the day. Lowering CIGs will accompany this, with MVFR conditions expected by late afternoon/early evening. Generally light southerly winds tonight will become more easterly by Saturday morning and increase through the day. By late afternoon, expecting sustained winds between 10 and 15 knots along the coast with wind gusts around 20 knots. Inland areas will generally remain under 10 knots during this time. /26 PREV DISCUSSION... /issued 535 PM CDT Fri Jun 5 2020/ NEAR TERM UPDATE /Now Through Saturday/...The region remains in an area of upper level weakness today, with ridges dominating areas to the east and west. This pattern will begin to break down overnight tonight with the advancement of Tropical Storm Cristobal northward towards the Gulf coast. Meanwhile, some scattered showers and storms have persisted over the open Gulf waters and along the coast this afternoon. Furthermore, an MCS is moving southward over Mississippi and central Alabama. Although, the HRRR shows this feature breaking up somewhat by the time it gets closer to the northern Gulf coast. This will continue to be monitored. With the loss of daytime heating, the chances of rain and storms will then decrease late this evening and overnight. Rain chances (as well as thunderstorm chances) will increase once again Saturday morning from the south due to an outer rain band from Tropical Storm Cristobal as it progresses north. PWATs will increase from around 1.8 inches this afternoon to over 2 inches by Saturday afternoon. Although, the heavier rain associated with Cristobal is not expected to begin until late Saturday into early Sunday. Winds will begin to increase along the coast late Saturday afternoon as well, but again, the stronger winds are not expected to begin until Saturday night. The Tropical Storm Watch was upgraded to a Tropical Storm Warning this afternoon and now also includes all Florida Gulf waters as well as most bays (except for Eastern Choctawhatchee Bay). Low temperatures are expected to be in the lower to mid 70s tonight due to increased moisture. Areas right along the coast could see even warmer lows, in the upper 70s. With increased cloud cover and rain chances, highs tomorrow will likely only reach the mid to upper 80s (with slightly cooler temperatures at the beaches). The HIGH RISK of rip currents continues for the coastal Alabama and northwest Florida panhandle beaches through early next week due to increased swell from Tropical Storm Cristobal. /26 SHORT TERM /Saturday night Through Monday night/...Tropical Storm Cristobal is forecast to be centered over the central Gulf of Mexico Saturday evening, and track northward before moving inland across southern Louisiana Sunday evening, and then move northward across the state of Louisiana throughout the day Monday. Deep layer moisture will be high through early next week, with precipitable water values increasing to between 2.2 to 2.7 inches Saturday night and Sunday due to the surge of tropical moisture around the northern edge of Cristobal`s large scale circulation. Considering the amount of deep tropical moisture in place, some of the more defined storms will be efficient, locally heavy rainfall producers bringing potential of localized flooding. Bands of heavy rainfall approaching from the south and will be most focused across extreme southwest Alabama and the inland southeast Mississippi where a Flash Flood Watch is now in effect. The latest rainfall forecast indicates potential for 3 to 6" of rain with locally higher amounts possible for these areas. Heavy rates will potentially lead to flooding of urban/low lying areas. Key take-aways for Cristobal impacts in our area at this time include: - The eastern wind field will expand outward as Cristobal approaches the coast, so a Tropical Storm Warning is now in effect for the coastal counties as far east as Destin, Florida. This warning may be expanded further northward over the next 24 hours, and will be highly dependent on storm intensity, location, and track. - Our highest confidence is in the threat of dangerous high surf and rip currents. - At least minor coastal flooding looks likely this weekend, particularly around the time of high tide on Sunday. If the storm tracks closer to the area, then the threat of storm surge would increase. - Heavy rainfall is possible, and amounts will ultimately be dependent on the track of the storm. The heaviest rain is expected to fall in areas that are still in drought, so urban and low lying areas currently appear most susceptible to flooding. - There is the potential for isolated tornadoes developing Sunday into Sunday night within outer rain bands over the southern portion of the area. Lows Saturday night will be in the upper 60s to lower 70s inland, with mid 70s along the beaches. Lows Sunday and Monday nights will range from 70 to 75 degrees inland, with upper 70s along the beaches. High temperatures Sunday and Monday will range from 80 to 85 degrees. /22 EXTENDED TERM /Tuesday Through Friday/...Cristobal continues to move inland and becomes absorbed into an upper trough early to middle of next week. A very moist pattern looks to remain over our region, so we will keep a numerous to definite coverage to showers/storms across the forecast Tuesday and Wednesday, with mainly scattered coverage of showers/storms overnight and on Thursday and Friday. Additional rainfall amounts up to 1" will be likely with locally higher amounts possible during the expected period. /22 MARINE...Light to moderate southeasterly winds will prevail through this evening. Winds will then become more easterly and increase Saturday as Tropical Storm Cristobal advances northward across the Gulf towards the coast of Louisiana. Seas will also increase during this time. Winds will then shift to be from the south by Sunday night as Cristobal moves over Louisiana and Mississippi. Please refer to the National Hurricane Center for the latest advisory on Cristobal. /26 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...Flash Flood Watch from Sunday morning through Monday evening for ALZ261>266. Tropical Storm Warning for ALZ263>266. High Rip Current Risk through late Monday night for ALZ265-266. Coastal Flood Advisory from 1 PM Saturday to 7 AM CDT Monday for ALZ263>266. High Surf Warning from 1 PM Saturday to 7 AM CDT Monday for ALZ265-266. FL...Tropical Storm Warning for FLZ202-204-206. High Rip Current Risk through late Monday night for FLZ202-204- 206. Coastal Flood Advisory from 1 PM Saturday to 7 AM CDT Monday for FLZ202-204-206. High Surf Warning from 1 PM Saturday to 7 AM CDT Monday for FLZ202-204-206. MS...Flash Flood Watch from Sunday morning through Monday evening for MSZ075-076-078-079. GM...Tropical Storm Warning for GMZ630>635-650-655-670-675. Small Craft Advisory from 7 PM Saturday to 7 AM CDT Monday for GMZ636. && $$ This product is also available on the web at: http://weather.gov/mob
Area Forecast Discussion
National Weather Service Nashville TN
745 PM CDT Fri Jun 5 2020 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Other than minor adjustments to hourly temp and dew point trends, tonight`s forecast remains on track. Latest HRRR still suggesting an isolated shower or storm in our southwest counties over the next couple of hours. Otherwise, some patchy late night fog expected. && .AVIATION... 00Z TAF DISCUSSION. VFR conditions are expected at airports this evening with decreasing cumulus clouds and some cirrus. Areas of fog overnight look to bring MVFR to IFR visibility to airports between 06-13Z with improvement back to VFR afterwards. Light and variable to calm winds are anticipated tonight into tomorrow morning. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......13 AVIATION........Shamburger