Sat 12:58 PM —Forecast Review — Not the best Saturday forecast. I got the windy conditions forecast right, but the cloud cover today is more than I had forecast based on yesterday’s models.
Here’s the actual wind gusts at noon today—
RTMA wind and wind gusts at noon today. (Click on image for a larger view.)
Additionally, there are light sprinkles moving through the area, not forecast by any of yesterday’s models.
I took a look to see if any model last night had forecast these mid-day sprinkles and last night’s 06zECMWF (not available until this morning) got this right.
However, the NAM-NEST missed it, as did the HRRR, HREF and Canadian models. I’m surprised by that.
Originally Posted Fri 7:27 PM —The deep upper and surface low of the New England coast will gradually move eastward. We’ll still be in the colder upper cyclonic flow through most of the weekend.
A warm upper ridge is poised to move in starting Monday, however, another storm system is expected by Thursday.
Here’s the current NAEFS forecast synopsis for Sunday at 11AM showing the departing upper low—
NAEFS model statistical “mode” version with overlayed GEFS model “bias-corrected” precipitation forecast for Sunday at 11 AM. Cold upper air feature is departing. Warm upper ridge ready to move in. (Click on image for a larger view.)
Saturday
Saturday’s weather will be similar to the past two days. Considerable sunshine in the morning with clouds and sun in the afternoon. VERY WINDY and gusty. Showers/sprinkles increasingly unlikely. Sunshine very late afternoon.
NBM high temperatures: Blue Bell, PA 52º Philadelphia, PA 54º Average to low uncertainty (based on standard deviation): ± 1.5º
Sunday
Sunday will be similar to Saturday. Probably no sprinkles. A bit warmer and less windy.
NBM high temperatures: Blue Bell, PA 54º Philadelphia, PA 56º Average to low uncertainty (based on standard deviation): ± 1.7º
Sat 6:07 PM —Forecast Review —A few sprinkles moved in as early as 3:30 PM, earlier than I had forecast. The ECMWF was noteworthy as having predicted this. The main area of showers is poised to move in as originally expected after 6 PM. The showers appear to be somewhat heavier and further south than forecast.
MRMS radar image at 6 PM. Showers poised to moved in soon. (Click on image for a larger view.)
Saturday: A clipper system near the Great Lakes will move just north of our area this evening. Upper air support is not favorable for intensification and only very light showers will move in after 6 PM, mostly (but not exclusively) north of the Philadelphia area.
Before the light showers, cloudiness increases from the west, becoming mostly cloudy after 3 PM.
Here’s the current satellite water vapor image—
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. Area of rain at 7 AM is 425 miles from here, corresponding well to the latest GFS forecast.
Here’s the latest HRDPS which is the most aggressive with the showers in our area—
Canadian high resolution 1 hour precip forecast at 7 PM. (Click on image for a larger view.)
Sunday: Periods of sun and clouds. Mild Showers move in during the late evening hours. High 63º
Rain moves in after midnight Sunday for a rainy Monday.
