Wednesday night’s rain

Update Thu 08/11 @ 9:24 AM — Areas, especially in NJ, had some decent amounts of rain Wednesday night—

MRMS accumulated rain Wednesday night into Thursday morning. Many areas in NJ had over one inch. (Click on image for a larger view.)

Compare the above actual rain amounts above to the forecast of the experimental LAMDAX model shown here. Not perfect, but not bad!! Better placement than the NAM-NEST.

The experimental LAMDAX isn’t available every day, and when available, only web type low resolution graphics are released; no raw data is available outside of NOAA.

Rain Wednesday night into Thursday morning

Updated Wed 8/10 10:33 PM — Tonight’s models are showing considerably more rain tonight than previously forecast, in line with the experimental LAMDAX model. Many areas, but not all, may receive 0.4 to 0.8 inches. Every model shows a bullseye of localized heavy rain, but the location varies by model. Here’s the latest NAM-NEST, which is most extreme with its bullseye —

NAM-NEST. The bullseye of heavy rain is 4 inches, probably a modeling error.

Updated Wed 8/10 9:08 PM — Updated with the latest LAMDAX precip forecast which just became available below.

Updated Wed 8/10 5:54 PM —Last night, while a very few areas received a substantial rainfall, most areas last night only received a paltry amount. Even the area around Citizens Bank Park only received about 0.30″ yet it caused two rain delays.

Rainfall totals for last night (Tuesday evening/night), according to the MRMS—

MRMS total 24 hour rainfall (Tuesday evening/ night) (Click on image for a larger view.)

As for this evening (Wed), there’s lack of model agreement about where a low pressure system will develop along the stalled frontal boundary that moved through yesterday. This translates into a wide range or forecasts, most with rain south of the immediate PHL area.

The consensus forecast based on the NBM

NBM total rainfall forecast Wednesday night into early Thursday morning. Most of the rain falls from Philadelphia and southward. (Click on image for a larger view.)

We already know this forecast will be off….the same models forecast rain already beginning in some areas right now, but nothing to be seen on radar and I see blue skies outside my window.

Most of the rain will be gone by 8 AM, but a few areas may have some lingering showers, all gone by 10-11 AM, except in eastern NJ. Not a drought-buster.

Just for the heck of it, here’s the latest experimental LAMDAX high resolution model forecast, showing a very different location of the heaviest precipitation . (The LAMDX looks like it’s being developed and groomed for the next generation of models, likely to be ready for operational release in 2024. It’s still experimental and not finalized.) —

Today’s experimental 12z LAMDAX showing much different location of heaviest precip axis. The LAMDX has limited availability with only pre-made graphics, no raw data available. Click on image for larger view.

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Update Sun 08/07 @ 9:59 AM — No rain today. Heat index max from the latest 12z NBM model —

12z NBM shows max heat indices (apparent temperatures) over 100º between 2-3 PM. (Click on image for a larger view.)

The high temperature forecast is now closer to 92º (from yesterday’s forecast of 93º) but forecast dew points are somewhat higher.

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Updated Fri 8/05 9:52 AM —We had some showers Thursday evening, more widespread than had been forecast by the models. 

For today, Friday, there’s a range of forecasts, with many models showing little in the way of rainfall to as much as an inch.  The trend is for not much.  Timing varies from as early as mid to late afternoon, to storms moving through late evening and even after midnight.

I’m curious whether the new, experimental limited area model clarifies the forecast. It has maintained a forecast of a moderate cluster of storms early evening.  

Updated Wed 9:38 PM — The forecast is unchanged for Thursday.  Very hot and humid.  A few scattered thunderstorms my pop up after 5 PM, but with low vertical shear, they won’t last long or cover much territory.

A cold front approaches on Friday. A large cluster of thunderstorms will develop in western suburbs and move into the city between 6 and 8 PM. Some heavy rain possible with these storms. Shear values will again be low, so we’ll have to see if the models are getting this right.

Update Tue 08/02 @ 8:20 PM — Not much happening except increasing heat. A weak front moved through about 1 PM today. A few isolated showers broke out with the frontal passage (not predicted by the models.)

The increasing temperatures for Wednesday and Thursday are well-advertised by the regular radio and TV media.

Here’s some specifics info for Thursday based on the current NBM model —

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Weather… and Other Things 'Up in the Air'

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