September 26, 2022: 48-Hour Weather Report and Intermediate-Term Outlooks; Tropical

Updated at 3 am EDT September 27, 2022 to incorporate the latest information on Hurricane Ian.

Here is what we are paying attention to this evening and the next 48 hours from this afternoon’s NWS Forecast.

...Hurricane Ian sets path towards Florida with the threat of flooding,
high winds, and severe weather increasing...

...Heavy rain continues for portions of the Lower Great Lakes Tuesday...

...Cool and unsettled weather expected to persist across the Northeast and
Great Lakes through at least mid-week...

...Well above average temperatures forecast throughout the West, with
excessive heat impacting parts of southern California...

Continuation of the NWS Short Range Forecast (It is updated twice a day and these updates can be found here.

The focus of attention this week will be Hurricane Ian, which is forecast
by the National Hurricane Center to rapidly intensify into a major
hurricane and move northward towards the Gulf Coast of Florida. The threat
for heavy rain, high winds, and severe weather will be increasing as the
storm approaches. Showers currently across the Keys to southern Florida
are forecast to become heavier and more frequent as the outer rainbands
associated with Ian begin to overspread the state. There is a Moderate
Risk of Excessive Rainfall on Tuesday for coastal portions of the southern
Florida Peninsula and for the northern half of the Peninsula on Wednesday
as heavy rainfall from the storm, on top of already wet antecedent
conditions, may lead to scattered to widespread instances of flooding. The
Storm Prediction Center has also highlighted the same regions with Slight
Risks for the threat of tornadoes. Winds are also expected to increase as
Ian approaches, with tropical storm force winds currently forecast to
reach southern portions of the Peninsula on Tuesday.

Meanwhile, an amplifying upper-level trough is forecast to continue
bringing cool and unsettled weather from the Great Lakes to the Northeast
through mid-week.  The strength of the upper trough will be maintained by
reinforcing surges of cooler air diving across central Canada.  This
pattern will favor damp, dreary weather to persist into Wednesday.  There
is a Slight Risk of Excessive Rainfall along Lake Erie and a Marginal Risk
along Lake Ontario on Tuesday as cold air aloft flowing across the warm
waters of the Great Lakes will destabilize the atmosphere and could lead
to heavy lake-effect rain. In addition to the threat for heavy rain,
temperatures will remain unseasonably cool across the Midwest and
Northeast and spread into the Southeast Wednesday. Most of the Upper
Midwest, Great Lakes, and interior Northeast will see highs in the
upper-50s and low-60s, with some locations in the Upper Great Lakes only
reaching the upper 40s Tuesday. There are Frost Advisories in effect for
portions of the Upper Mississippi Valley Tuesday morning as lows will
bottom out in the mid-30s. Southern portions of the Midwest as well as the
coastal Northeast will see highs in the mid-60s to low 70s. Temperatures
across the Southeast will cool from the upper 70s and low 80s on Tuesday
to the mid-70s Wednesday.  

In contrast to the eastern half of the country, Summer-like, well above
normal temperatures are forecast to remain over much of the West as a
strong upper-level ridge passes over the region. The hottest weather is
expected over the Southwest and southern California with highs in the
mid-100s for the interior deserts and in the 90s for all but coastal
portions of Southern California. Excessive Heat Warnings and Heat
Advisories remain in effect for the Greater Los Angeles/San Diego regions
as well as adjacent portions of the Sonoran Desert. Elsewhere, well above
normal temperatures will stretch from the Intermountain West to the
northern Rockies and northern High Plains. Highs on Tuesday and Wednesday
are forecast to soar into the upper 80s and low 90s.

Current forecast of track and other information

Maps that relate the forecast to geography can be found by clicking  Here for Day 1 and Here for Day 2.

Here is a 60-hour animated forecast map that shows how the short-term forecast is expected to play out.

If it needs to be updated click here.

HAZARDS OUTLOOKS

Click here for the latest complete Day 3 -7 Hazards forecast which updates only on weekdays.  Once a week probably Monday or Tuesday I will update the images. I provided the link for readers to get daily updates on weekdays. Use your own judgment to decide if you need to update these images.  

Worldwide Tropical Forecast

(This graphic updates on Tuesdays) If it has not been updated, you can get the update by clicking here  This is a new approach and covers weeks 2 and 3 not weeks 1 and 2. It has more information but I am having trouble getting used to it. As usual, it comes with a discussion so I thought I would show that discussion tonight. I will not do that every night but if you click the link you will have that discussion.

Outlook Discussion
Last Updated – 09/20/22
Valid – 09/28/22 – 10/11/22
The Madden-Julian Oscillation (MJO) weakened during early to mid-September which is likely due to destructive interference with the ongoing La Nina. The 200-hPa Velocity Potential field depicts very small anomalies throughout much of the global tropics with the largest anomalies, associated with upper-level divergence, centered over the Maritime Continent. Although enhanced low-level trade winds remain anchored across the equatorial central Pacific, anomalous 200-hPa easterly winds shifted east to 150E for the first time since early June. This may indicate that a remnant MJO signal is propagating eastward across the Pacific to the Americas during mid-September. Objective wavenumber-frequency filtering of the CFS and ECMWF models depicts this remnant MJO, albeit in a weakened state, shifting east over the Western Hemisphere during the next two weeks and then crossing Africa to the Indian Ocean by week-3. The ECMWF and GFS models depict anomalous low-level westerlies and reduced wind shear over the East Pacific, Caribbean Sea, and parts of the tropical Atlantic during the next two weeks. These model projections along with the background state of La Nina is expected to support a fairly active period in the Atlantic basin through at least the beginning of October.

On September 14, Tropical Depression Seven developed over the tropical Atlantic and strengthened to a Category-1 Hurricane Fiona a few days later. Fiona tracked across Puerto Rico and then made a second landfall in the Dominican Republic. As of September 20, Fiona is forecast to strengthen to a Category-4 hurricane and track northward to near Bermuda later this week. Tropical Depression 8 formed on September 20 in the subtropical central Atlantic and is forecast to track northeastward. A couple of tropical cyclones, the 13th and 14th of the 2022 season, formed over the East Pacific during the past week. In the West Pacific, Typhoon Nanmadol recently made landfall in the Kyushu Islands of southern Japan.

The National Hurricane Center (NHC) is currently monitoring a tropical wave located several hundred miles east of the Windward Islands. Since this system is likely to become a tropical cyclone late in week-1, no tropical cyclone (TC) development area is posted for the Caribbean Sea during week-2. This disturbance should be monitored closely as it is expected to enter a favorable environment for strengthening heading into week-2 and could eventually impact areas of the Caribbean and southeastern United States. Multiple tropical waves are forecast to emerge from western Africa during the next two weeks and background state is expected to be conducive for one of these waves to develop across the Main Development Region of the Atlantic during week-2. Due to uncertainty on location at this time lead, a 20 percent chance over a broad spatial extent is posted. By week-3 (Oct 5-11), the main focus for TC development in the Atlantic basin climatologically shifts to the western Caribbean.

In the East Pacific, NHC is monitoring a couple of areas of low pressure for TC development during the next five days. Since any development is expected to be slow to occur and may not occur until early week-2, a 20 percent chance of genesis is designated for week-2. Dynamical models support a broad 20 percent chance of TC development across parts of the West Pacific during week-2, while a model consensus and continuity increases chances to 40 percent across the South China Sea.

The precipitation outlook during weeks 2 and 3 are largely based on La Nina precipitation composites and a historical skill-weighted blend of GEFS, ECMWF, CFS, and Canadian ensemble forecasts. Most likely TC tracks were also considered heading into the week-2 period. For hazardous weather concerns in your area during the next two weeks, please refer to your local NWS office, the Medium Range Hazards Forecast from the Weather Prediction Center (WPC), and the CPC Week-2 Hazards Outlook. Forecasts issued over Africa are made in coordination with the International Desk at CPC.

Detailed Maps and Reports for the Western Atlantic and the Pacific Oceans

Below are three maps that summarize the situation for the Atlantic, Eastern and Central Pacific. Additional information can be accessed by clicking HERE

First the Atlantic

Click to view the forecast map and have access to additional information https://www.nhc .noaa.gov/gtwo.php?basin=  atlc&fdays=5

Then Eastern Pacific

Click to view the forecast map and have access to additional information https://www.nhc.noaa.gov/gtwo.php?basin=epac&fdays=5

Then Central Pacific

Click to view the forecast map and have access to additional information https://www.nhc.noaa.gov/gtwo.php?basin=cpac&fdays=5

And the Western Pacific

Click to view the forecast map and have access to additional information https://www.metoc.navy.mil/jtwc/jtwc.html

Some Intermediate-Term Outlooks

Links to “Outlook” maps and discussions for three time periods. Days 6 – 10, Days 8 – 14, and Weeks 3 and 4.  An outlook differs from a forecast based on how NOAA uses these terms in that an “outlook” presents information from deviation from normal and the likelihood of these deviations.

You have to click on the links because they do not update automatically and I do not want to have stale images in the article. But it is not difficult to click on a link and you get a large image plus a discussion. On Fridays in a separate article, we will show the images and provide a link in this article that article. But remember what you will see is the images as of Friday. But here you can get the current images simply by clicking on them. Then hit the return arrow at the upper left of your screen to return to the article. You will not find this information easily anywhere else.

The following is provided to help the reader relate the maps and the discussion that comes with the maps to how NWS will describe an area of the U.S.

https://i0.wp.com/www.wpc.ncep.noaa.gov/bndrys1.gif?w=1100&ssl=1

Days 6 – 10 Days 8 – 14 Weeks 3 and 4
https://www.cpc.ncep.noaa.gov/products/predictions/610day/ https://www.cpc.ncep.noaa.gov/products/predictions/814day/ https://www.cpc.ncep.noaa.gov/products/predictions/WK34/

Right now you can find these maps here (We show them every Friday there but you can click above and find them).

World Forecast for Day 6 (Currently Set for Day 6 but the reader can change that)

World Weather Forecast produced by the Australian Bureau of Meteorology. Unfortunately, I do not know how to extract the control panel and embed it into my report so that you could use the tool within my report. But if you visit it Click  Here and you will be able to use the tool to view temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool. Return to this report by using the “Back Arrow” usually found top left corner of your screen to the left of the URL Box. It may require hitting it a few times depending on how deep you are into the BOM tool. Below are the current worldwide precipitation and air pressure forecasts for six days out. They will not auto-update and right now are current for Day 6. If you want the forecast for a different day Click Here  I will try to update this map each day but you have the link so you can access the dashboard and get a wide variety of forecasts.I mostly rely on the reader to interpret world maps. For this map, areas of expected precipitation for the date and time shown are clearly shown. The number of High-Pressure systems shown is called the Wave Number. Maybe I will discuss WN someday. But it shows how many Rossby Waves there are around the World. Sometimes they are hard to count. Counting Low-Pressure systems should provide the same WN.  Rossby Waves are the way the temperature distribution of the Planet remains in balance. It is basically the science of fluid dynamics.  It can be very helpful in predicting the movement of weather patterns.  You can snip an area of interest and move it into MS Paint and enlarge it.

Month to Date Information

Month to date Temperature can be found at https://hprcc.unl.edu/products/maps/acis/MonthTDeptUS.png

Month to date Precipitation can be found at  https://hprcc.unl.edu/products/maps/acis/MonthPNormUS.png

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