Category Archives: Philadelphia Weather Outlook

THIS WEEK’S WEATHER

Tue 7:12 PM —Forecast Review — The storms that came through this evening were impressive and stronger than I would have guessed based on forecast severity parameters which were high in CAPE and Precipitable Water (PWAT) and Lifted Index. and somewhat middle of the road in Vertical Shear and Helicity. (All based on the HRRR forecast values.) As mentioned yesterday, the trigger was a “potent” short wave.

However, my update (below) posted at 3:51 PM showed very impressive vertical motion ahead of the line of storms to our west, and the greater strength of the storms was less of a surprise when they moved in.

Several tornadic signatures showed on radar. Here’s one that was impressive in upper Montgomery county—

This PHL Terminal Doppler Radar (courtesy of Weathertap.com) shows a likely tornado in the white box, based on radar signature. (Click on image for a larger view.)

Another tornadic signature in eastern Montgomery county may or may not be an actual tornado.—

This PHL Terminal Doppler Radar (courtesy of Weathertap.com) shows a possible tornado in the white box, based on radar signature. (Click on image for a larger view.)

What was really impressive was the experimental REFS model which was accurate with its timing of the lead storms in Philadelphia and the subsequent storms that are still lingering. The HRRR, our current high resolution operational model, really got the timing of today’s storms wrong.

The REFS is scheduled to become operational in early 2026, if NOAA is allowed to do its wonderful job. The REFS and the RRFS will be replacing several older, less-skillful “legacy” models such as the NAM and HREF and HIRESW-ARW models.

More about this on my RRFS page.

“Tracking” Storms?? What does that really mean??

As I’ve said here before, I avoid the using the expression “tracking” the storms. The TV people use this all the time. Storms, and especially thunderstorms, are dynamic processes. They can form at a point almost instantly. They’re not a train that arrives at a scheduled time. There’s nothing to “track”. Case in point are the storms that just formed over Center City after 4 PM.

PHL Airport Terminal Doppler Radar at 4:10 PM Click to animate (Click on image for a larger view.)

The appearance of these storms between 4-5PM suggests the REFS is doing a great job with thunderstorms.


Tuesday’s Storms Update

Posted Tuesday 07/08/25 @ 3:51 PM — At 3:45 PM, radar and hourly updated RAP model shows a line of storms far west of the city with significant upward vertical motion (vertical velocity pressure, Omega) ahead of the line. This signifies likelihood of significant strengthening of storms as they approach our area—

Radar 3:45 PM with RAP model Omega overlay. Significant vertical upward motion predicted ahead of the storms (X) suggests likelihood of intensification. (Click on image for a larger view.)

The latest REFS (experimental) shows some storms develop here as early as 5 PM, but the main batch of storms arrive near the city between 6 and 8 PM.

12z REFS 1 hour rain and standard deviation (contours) at 5 PM Not sure if this is still forecasting a bit early. (Click on image for a larger view.)

For comparison I’ve resurrected an old table with some significant storm histories. The highlighted column is today’s severity parameters and allows you (and me) to compare with today’s values.

Severity Parameter
(HRRR)
Sept 1 , 2021
Tornado Outbreak
(example of highly severe)
Recent
4-1-23
Tornadoes
(Example of severe)
Recent 08-07-23
18z HRRR Bow Echo
07-08-25
Today’s
18z
HRRR
&
Impact

Notes
CAPE
Joules/kg
3500-4200
⚑⚑⚑⚑
2100
⚑⚑
2600
⚑⚑
2680
⚑⚑
Helicity
m^2/s^2
1350
⚑⚑⚑⚑⚑
655
⚑⚑
726
⚑⚑
403
Vertical Shear
1/sec
40-46
⚑⚑⚑
40-45
⚑⚑⚑
30
20
Precipitable Water 2.7″
⚑⚑⚑⚑
0.83”
2.1″
⚑⚑

2.6″
⚑⚑⚑⚑
Heavy rain potential
Lifted Index
º K
minus 6º
⚑⚑
minus 9.3º
⚑⚑⚑
minus 9.9º
⚑⚑⚑
Minus 8.3º
⚑⚑
HRRR Hail
inches
1.9
⚑⚑
1.4
1.8
⚑⚑

1.8
⚑⚑
Peak Wind Gusts
mph
40-50
⚑⚑
40-50
⚑⚑
65mph
⚑⚑
51.6mph
⚑⚑
NJ area
Storm Motion Shear Vector
Alignment
Aligned – ~ 90º
⚑⚑
Almost aligned
⚑⚑
aligned
⚑⚑
Somewhat aligned
250 mb
Jet Stream Wind
mph
63
135
⚑⚑
74
41
Severity Parameters Impact: ⚑ indicates favors Severity ⚐ indicates Possible Severity
↓ indicates works against Severity ⇩ Significant, but less impact

I just want to add that the HRRR shows the heaviest storms moving north and south of the immediate PHL area. Not true of the REFS and RRFS. Something to watch.

A note for those of you who are visiting this site from “X“.
Due to the highly unbalanced political environment on X, I’ve considerably cut back auto-posting there. To receive all of my forecast postings, I suggest following me on mastodon.social or bluesky.social


Tuesday’s Storms Update

One More Thing: the latest Canadian GDPS “with AI nudging” also suggests earlier timing, as early as 4PM, similar to the REFS below.

Posted Tuesday 07/08/25 @ 7:28 AM — A potent short wave and front will move through Tuesday evening. Ahead and along with this disturbance will be strong dynamics that promises more wide spread heavy rainfall and the potential for somewhat more severe storms than Monday.

In terms of timing, the REFS (experimental) still shows some showers/storms as early as 3-5 PM in the western suburbs, then moving eastward. The latest RRFS (experimental) continues to be about two hours later, with storms approaching the immediate PHL area around 6-7 PM.


The latest HRRR shows storms approaching the immediate PHL area around 6-8 PM, somewhat earlier in western suburbs.

06z HRRR forecast “simulated radar” at 8 PM Tuesday. (Click on image for a larger view.)

In terms of severity, greatest likelihood is in western sections about 5-7 PM. Heavy rain possible throughout the area.


Tuesday Storms

Posted Monday 07/07/25 @ 7:59 PM — Just wanted to add that the GFS shows some storms in Harrisburg moving through our area around midnight. Not shown in REFS or RRFS forecasts for tonight (Monday).

Posted Monday 07/07/25 @ 7:33 PM — The storms developed in many (but not all) areas around Philadelphia this afternoon. Here’s the MRMS rainfall totals—

MRMS rain-gauge measured rainfall combined with rain-gauge calibrated and interpolated radar-based summary of ACTUAL RAINFALL RECEIVED. Color shading is in inches. Line contour numbers are in mm. (25.4 mm= 1 inch)      (Click on image for a larger view.)

Tuesday should be mostly sunny hot and VERY humid again. A slight dip in the jet stream and a potent ‘short wave’ will approach, causing the development of widespread showers and thunderstorms beginning about 4 PM. Additionally, we’ll be near the right entrance region of a jet streak, enhancing available energy.

The latest GFS shows this potent area of upward motion around this short wave.

18z GFS forecast for 5PM showing strong concentration of upward vertical velocity pressure. Strong, possibly severe storms are possible. (Click on image for a larger view.)

The REFS did well today and I’ll stick with its forecast for Tuesday.

12z REFS forecast rain with standard deviation (contours) at 6 PM Tuesday. (Click on image for a larger view.)

The REFS has showers breaking out west of the city as early as 3 PM, but widespread showers and thunderstorms are expected by 4-6 PM.

(It should be mentioned the the latest RRFS has the storms moving in about 2 hours later than the REFS shown above. )

Several hours of widespread rainfall are expected with storms moving into NJ by 5-6 PM. Localized areas of 1-3″ of rain expected. Unlike today’s storms which were mostly heavy rain, Tuesday’s storms will have somewhat higher vertical wind shear and areas of elevated helicity. Some severe storms possible, especially into South Jersey and Delaware.


Monday Update

Posted Monday 07/07/25 @ 10:10 AM — The moisture associated with the remnants of tropical depression Chantal have started to move across our area today. Any sunshine will induce instability and thunderstorm formation. Here’s the latest REFS hourly rain forecast at 1 PM, 3 PM and 5 PM today—

06z REFS hourly rainfall with standard deviation (contours) 1 3 5 PM today. (Click on image for a larger view.)

Most of the activity will be in the afternoon hours and taper off by 9 PM.

Showers will be scattered, but any storm will be slow moving and capable of dropping heavy rainfall. Precipitable water forecasts are as high as they get around here, 2-3″ – 2.5″ in some areas. Flooding type rains are possible.

RRFS forecast precipitable water at 4 PM. As high as they get outside of the tropics. (Click on image for a larger view.)

Originally Posted Sun 5:37 PM —The remnants of tropical depression Chantal are located in North Carolina and the moisture and energy of this weak system is expected to move over our area on Monday.

5 PM Current satellite water vapor image with superimposed RAP model 500-1000 mb thickness lines (yellow), Mean Sea Level Pressure isobars (black contours) potential vorticity (fine violet contours) with superimposed MRMS RADAR. Water Vapor Imagery reveals emitted water vapor infrared TEMPERATURE, NOT REFLECTED LIGHT from CLOUDS. Current position of CHANTAL is indicated as {L} (Click on image for a larger view.)

Some showers are breaking out in Delaware at this time (Sunday evening) and some showers may make into Delaware County and just south of the city by 8 PM.

More numerous showers and thunderstorms will develop on Monday. Shear and helicity values are weak. The main issue with these showers and storms will be the possibility heavy, slow moving rainfall. The showers will be scattered.

For Monday, a few scattered showers are possible in the morning, but the real deal will be during the afternoon where daytime heating will induce these showers and storms. 2PM to 8 PM will be the likely time slot with showers peaking around 4PM – 5 PM Monday. It will be warm (mid 80s) and VERY humid.

Here’s the latest REFS forecast for 5 PM

12z REFS forecast for 5 PM Monday. Previous 1 hour precipitation with standard deviation (contours)(Click on image for a larger view.)

Daytime hours on Tuesday look to be dry until about 4 to 8 PM, when showers and storms move in from the southwest. It will be very warm and VERY humid on Tuesday


THIS WEEK’S WEATHER

Thursday Evening Update

Posted Thursday 07/03/25 @ 6:11 PM — As forecast this morning, much of the energy and moisture for thundershower formation is north of our area.

Here’s what it looks like at 6 PM—

6 PM RADAR with RAP model vertical velocity pressure (omega) in green contours. There are two areas of strong vertical motion to our west, but what appears to be lacking is moisture. (Click on image for a larger view.)

The latest REFS still shows some showers here around 8 PM, but it might be over-forecast.

Experimental REFS (12z) 1 hour accumulated rainfall at 8 PM. Possibly overdone. (Click on image for a larger view.)

The Fourth of July Weekend is looking quite nice, sunny but increasingly warm. Near 90º on Saturday, low 90s and more humid on Sunday.


Thursday & Fourth of July Extended Weekend

Posted Thursday 07/03/25 @ 9:38 AM — A front will move across the area with an upper level trough Thursday evening. Most of the energy and moisture will move to our north. Compared to recent thunderstorms, precipitable (cloud water) will be in the 1.4″ range compared to 2.1″ in recent storms, so rainfall amounts will be lighter.

With the exception of New Jersey, which may see some isolated storms this afternoon, the area of showers and storms moves through the immediate Philadelphia area between 7PM and 11 PM, with the latest REFS leaning towards 9-10 PM —

06z REFS 1hour prior rainfall with standard deviation (contours) at 10 AM (Click on image for a larger view.)

The Fourth of July Weekend is looking quite nice, sunny but increasingly warm, especially by Sunday.

A note for those of you who are visiting this site from “X“.
Due to the highly unbalanced political environment on X, I’ve considerably cut back auto-posting there. To receive all forecast postings, I suggest following me on mastodon.social or bluesky.social


Wed 9:30 AM —Forecast Review — Rainfall over the past several days was impressive, exceeding all model estimates. More amazing is the fact that we couldn’t get much of any rain here at all just a year ago.

Here’s the latest MRMS rainfall estimate over the past 72 hours. (It’s still raining in eastern NJ, so these numbers aren’t final.

MRMS rain-gauge measured rainfall combined with rain-gauge calibrated and interpolated radar-based summary of ACTUAL RAINFALL RECEIVED. Color shading is in inches. Line contour numbers are in mm. (25.4 mm= 1 inch) Time period is 72 hours back.      (Click on image for a larger view.)

What difference does a year make? Last year at this time, we were ascending on the solar cycle curve, something well-studied and associated with decreased rainfall.

This year, we’re descending on the same cycle curve, having peaked a few months ago. We’ve just passed the solar maximum of this cycle. This climate change is especially prominent over periods of two solar cycles– the double cycle is called the Hale Cycle (The Hale Cycle refers to the magnetic polarity of sunspots that reverse every two solar cycles). Is this Hale Cycle the reason for last season’s drought and our recent rainfall pattern change? Maybe.

Wednesday Update

Posted Wednesday 07/02/25 @ 9:51 AM — The models still show lingering rain in eastern NJ while clouds are expected to thin and break for some sun from west to east about 12 -3 PM

00z GDPS with “AI Spectral Nudging” forecast for 3 PM Wednesday (Click on image for a larger view.)
Wednesday Forecast

Posted Tuesday 07/01/25 @ 7:37 PM — The cold front hangs up along the coast as weak waves of low pressure move up along it. Expect additional light showers this evening and overnight into Wednesday morning. The sun will break through clouds from west to east on Wednesday afternoon.

Here’s the REFS cloud level forecast at 2 PM Wednesday

REFS cloud forecast for 2 PM Wednesday. Clouds hang tight along the shore, but sunshine increases from west to east during the afternoon. Some isolated showers possible in NJ and along the coast. (Click on image for a larger view.)

Tuesday Forecast

Posted Tuesday 07/01/25 @ 7:49 AM — Multiple rounds of showers and thunderstorms gave our region significant rainfall in some areas—

MRMS rain-gauge measured rainfall combined with rain-gauge calibrated and interpolated radar-based summary of ACTUAL RAINFALL RECEIVED. Color shading is in inches. Line contour numbers are in mm. (25.4 mm= 1 inch)   24 hour totals shown.     (Click on image for a larger view.)

A cold front moving through today. Some differences in the timing of the frontal passage with the HRDPS having the front move through about 4-5 PM, while the GFS has the front moving through about 8 PM with the showers and thunderstorms moving in 4:30PM to 7 PM

Similarly, the HRDPS has some showers moving through as early as 1 PM, especially just east of the city. The main line of showers and thunderstorms move through 3 PM -6 PM.

Based on yesterday’s model performance, I’m leaning towards the REFS and HRDPS which has showers and thunderstorms beginning at 3:00 PM to 4:30 PM, with some scattered activity possible as early as 1-2 PM mainly east of the city.

00z REFS forecast preceding 1 hour rainfall at 4 PM (Click on image for a larger view.)

All models have rain and thunderstorms continuing through the evening and night as low pressure develops along the front. Some rain may continue into early Wednesday morning. Heavy rain is expected.

Some thunderstorms may be strong to severe, but current forecasts of helicity and vertical wind shear are in the low- moderate range only.


Tuesday Forecast

Posted Monday 06/30/25 @ 5:41 PM — Showers and thunderstorms moved in from the south between 2:30 PM and 4 PM.

Towering cumulonimbus clouds about 2:20 PM Looking southeast along the Schuylkill bike trail. (Click on image for a larger view.)
Current Radar composite at 5:32 PM. Additional activity in Maryland may not make it here. The REFS shows some additional activity here about 2 AM Tuesday morning. (Click on image for a larger view.)

Very few of this morning’s models accurately predicted the timing and location of this afternoon’s storms. I always like to look back and see if any specific model did well. The HRRR, our best high resolution model, didn’t perform too well today, nor did the NAM-NEST. (The AI models don’t have the high resolution needed for thunderstorms.)

Looking back, the Canadian high resolution model (HRDPS) did reasonably well. The experimental REFS also did surprisingly well.

So with that, the REFS becomes “the model of the week”. It is currently forecasting showers/thunderstorms to return between 3 and 5 PM Tuesday afternoon. Some may be strong to severe. Stay tuned.


Monday Forecast Update

Posted Monday 06/30/25 @ 9:07 AM — Yesterday’s Model Blend (NBM) proved to be correct about the lack of showers this morning, and I’ll stay with the NBM for today’s forecast, with individual models showing a range of forecast times for showers and thunderstorms.

Pop up storms can occur anytime after 1 PM today with peak activity between 5 PM and 8 PM.

The latest NBM shows activity near the city picking up about about 1-2 PM just east of the city.

06z NBM prior 1hour rain forecast for 2 PM today. Location placement is almost never exact. (Click on image for a larger view.)

A considerable increase in coverage will occur later in the afternoon. Some areas may receive heavy rain in a short period of time.

Likely focus of heavier storms will be central areas of South Jersey in the mid afternoon and areas north of the city in the late afternoon.


Originally Posted Sun 8:50 PM —The ‘cold’ front that moved through Saturday has stalled just to our south and thunderstorms have been breaking out in South Jersey for much of Sunday, especially near the Delaware Bay and Cape May.

The front will return as a warm front on Monday. Large differences in the forecast exist for Monday morning. The AI version of the ECMWF and the latest GFS have scattered showers breaking out early Monday morning, while the regular ECMWF, the AI version of the Canadian GDPS keeps us dry until 2-4 PM.

The experimental RRFS has scattered pop-up storms in the morning; this may be an example of its tendency to over-forecast convective rain.

22z RRFS

The ECMWF-AI has so much precipitation and clouds in the morning that it keeps our high temperatures in the mid to upper 80s instead of the low 90s forecast by the drier forecasts.

The model blend (NBM) keeps us dry Monday morning as well, and I’m leaning towards its forecast. Its high temp in Philadelphia is 90.5º

It’s a tough call.

The models all come together by Monday afternoon with showers and thunderstorms popping up anytime between 1 PM and 4 PM and continuing into the evening. Peak time is about 6 PM according to the NBM.

Tuesday looks even more interesting, as a cold front moves into very moist and unstable air over the Philadelphia region. Stay tuned.


THIS WEEK’S WEATHER

Thursday Thunderstorms

Posted Thursday 06/26/25 @ 5:13 PM — The NWS has issued a severe thunderstorm watch. Some strong thunderstorms have developed far northwest of Philadelphia. Latest radar at 5 PM—

Radar with RAP model superimposed vertical motion (Omega). Note the upward vertical motion is centered west of the city. (Click on image for a larger view.)

The models have only been so-so with today’s forecast. Many models have forecast areas of storms that have not materialized late this afternoon. That’s particularly true of the experimental RRFS which forecast many areas of rain at this very time.

The trend mentioned in this morning’s update suggests the heaviest activity will remain just west of Philadelphia, as shown in the NBM graphic earlier.

The latest HRDPS and NAM-NEST capture the most likely forecast, again keeping the heavy rain to our west.

12z HRDPS forecast for 8 PM. The main activity remains to our west and eastern parts of the city may not see all that much rainfall. (Click on image for a larger view.)

These things are tough to forecast with high precision. I guess we’ll see what happens in the next few hours.


Thursday Forecast

Posted Thursday 06/26/25 @ 9:44 AM — Nailing down the forecast locations and timing of thunderstorms yesterday met with mixed results; the additional storms forecast towards midnight didn’t materialize.

Today, Thursday, presents another thunderstorm forecast challenge. Model forecasts range from storms developing as early as 2 PM near the city to storms mostly staying to our west and south (and South Jersey) through most of the afternoon and evening.

The NBM total rain accumulation captures the overall trend of any showers and storms staying to our west, south and east—

The 12z NBM just available keeps much of the Philadelphia area rain-free through 8 PM with any showers/storms staying to our west, south and South Jersey. (Click on image for a larger view.)

In contrast to this NBM forecast is the latest ECMWF-AI model, which does have showers and storms in the immediate Philadelphia area by mid afternoon.

Also in contrast to the NBM is the Canadian GDPS- with “AI spectral nudging” which has thundershowers in and near Philadelphia between 3 PM and 7 PM.

00z GDPS with AI spectral nudging. 1 Hour Convective precipitation at 6PM (Click on image for a larger view.)

A tough call. I guess we’ll find out.


Wednesday Night into Thursday

Posted Wednesday 06/25/25 @ 8:16 PM — Isolated to scattered storms developed. Very low wind shear has resulted in the storms forming and then collapsing. (Wind shear is needed to keep thunderstorms alive.)

Current radar at 8:10 PM

Radar at 8:10 PM with RAP model vertical motion (Omega- green contours.) In addition to having no wind shear, these storms are moving into areas of negative Omega (downward vertical motion- white boxes around negative green dashed contours.) The storms should collapse, but not before some areas get some quick downpours. (Click on image for a larger view.)

Today’s HRRR was unusually poor in forecasting the current storms. The experimental RRFS did better. Continuing with the RRFS, it is shows additional scattered short-lived storms through 3 AM as the backdoor cold front slowly moves through.

Thursday will have a mix of clouds and sun. Isolated to scattered storms are expected to begin to pop about 3 PM into Thursday evening. More details tomorrow.


Wednesday into Early Thursday

Posted Wednesday 06/25/25 @ 8:30 AM — As described yesterday, the heat dome will retreat late Wednesday as cooler high pressure slowly noses in from the northeast (backdoor cold front). Before that time, temperatures will again approach high levels, between 98º to 100º in and near the city.

Dew points will be higher today at peak temperature time, and I’ll have to resort to the Heat Index temperatures to capture the full impact. (I avoid posting heat index values since I think they’re often used to unnecessarily sensationalize, exaggerate heat episodes on TV broadcasts. Maybe not so today.)

06z NBM “Apparent Temperatures”, aka Heat Index. (Click on image for a larger view.)

As for thunderstorms, high heat, high humidity and several short waves ahead of the approaching backdoor cold front will create conditions ripe for thunderstorms with heavy rain. The latest HRRR is least on-board with storms here, but the AI models, the NAM-NEST, Canadian RGEM,and the RRFS show the possibility of isolated storms (especially in the wind shift/convergence zone in NJ) as early as 2PM.

Increasingly thunderstorm coverage expected late in the afternoon and especially in the evening hours (6 PM to midnight) where they should become more numerous. Not everyone will see a storm, but those that do will likely see some heavy rain. Severe winds, always a possibility, are not expected at this time.

To convey the scattered nature of the storms, here’s another model parameter that attempts to predict the strength of individual thunderstorm cells at 7 PM.

06z NBM Estimate “Radar Echo Heights” at 7 PM. Anything over 30,000 feet can be a very strong thunderstorm cell. Here, there are some above 40,000 feet. The exact predicted location of these storms cannot be taken literally with these models. (Click on image for a larger view.)

Wednesday- Heat Early Afternoon Reduced by Thunderstorms

Posted Tuesday 06/24/25 @ 7:57 PM — Disturbances moving across the upper heat dome are expected to bring showers and thunderstorms to our area Wednesday afternoon and evening. Some may be strong.

Water Vapor image Tuesday evening shows upper air disturbances poised to move towards us on Wednesday afternoon and evening as the heat dome retreats somewhat allowing them to reach us. (Click on image for a larger view.)

High temperatures of 99º and possibly 100º in parts of the city will be reached early, before 2 PM.

Thunderstorms develop and move in from the northwest and develop in place as early as 2 PM and continue into the evening. Impressive thermal instability (negative 8 “lifted index” and near 40 K index) and high CAPE values approaching 3000 J/Kg could make any storm strong to severe.

I’ll update Wednesday morning.


Tue 4:30 PM —Forecast Review — Another hot day, where the AI models were more accurate with their temperature forecasts than the very advanced NBM statistical Model Blend. (Although the Model Blend did fine when you factor in the standard deviation.)

Here’s the RTMA temperatures at 3:45 PM—

RTMA temperatures at 3:45 PM today. Black contours are 1º increments (Click on image for a larger view.)

Here’s the official readings from the NWS Philadelphia Airport KPHL

Highest Heat Index occurred at about 2 PM with the dew points being the highest. (Click on image for a larger view.)

Heat Continues

Posted Tuesday 06/24/25 @ 9:26 AM — Many models have similar high temperature forecast for today. The latest Model Blend (NBM) just became available. Here’s its forecast highs with degree of uncertainty (standard deviation) for today, Tuesday

12z NBM High Temperatures (not heat index or apparent temps) (Click on image for a larger view.)

Here’s the latest ECMWF-AI model high temperature forecast—

06z ECMWF-AI High Temp forecast (Click on image for a larger view.)

Here’s the new Canadian CMC GDPS-AI forecast—

00z CMC GDPS-AI model high temps for Tuesday (Click on image for a larger view.)

Heat Recap

It really felt hot today! Temperatures seem to have only reached 99º in this area, but dew points were 70º (and where highs were only 96º, e.g. Blue Bell, the dew points were closer to 74º and 75º

Here’s the RTMA @ 3:45 PM, capturing the area’s temperatures—

RTMA 15 minute repeat model. Actual with interpolated temperatures. (Click on image for a larger view.)

The NWS has modernized their website for KPHL airport, now showing temperatures every 5 minutes—

(Click on image for a larger view.)

Of interest is the localized area of showers that developed, as predicted by the new Canadian GDPS-AI along with the wind convergence zone—

Radar at 4:35 PM Wind convergence liine with showers in southern Cape May county, as predicted by the Canadian AI. (Click on image for a larger view.)

It’s interesting that the experimental RRFS did not predict these showers in Cape May. (The NAM-NEST did predict these as well.)

For Tuesday, here’s the latest ECMWF-AI temperature forecast—

ECMWF-AI Single Temperature Forecast for Tuesday(Click on image for a larger view.)

Stay cool!


Originally Posted Mon 9:22 AM —Yesterday’s high temperatures were diminished by the unexpected and unforecast clouds and showers.

The heat will be here for sure today.

Continuing with the “experiment” from yesterday, here is the new Canadian GDPS-AI along with the Model Blend (NBM) forecast high temps for today. likely about 3-4 PM—

00z Canadian GDPS-AI high temps for Monday (Click on image for a larger view.)

Here’s the Model Blend (NBM) high temps—

06z NBM forecast high temps. Contours are 1º increments. (Click on image for a larger view.)

The “Open Data” version of the ECMWF-AI single is very similar to the above.

Just to see if the Canadian has any unique insights, it is forecasting some thundershowers to develop in NJ at 3-4 PM due to the development of a moisture convergence zone—

CMC-GDPS Moisture convergence zone thundershowers.

Stay cool!