Heat and Humidity Return This Week

    Lately it's almost felt like summer was winding down and fall was right around the corner, as highs dropped to around 80° and into the low- to mid-80's with uncomfortable humidity almost nowhere to be found.  However, that's all changing starting today and for the week ahead as true summer-like conditions ramp back up and soupy air make a return.  Heat is already here to stay, and humid conditions will be on a gradual rise through the beginning of the week, culminating in the threat for scattered showers and storms for the latter half of the week.

   As I said before, high temperatures have already set into the region, but dew points will certainly be on the rise for tomorrow through Tuesday, as shown in the model data below.  We'll continue to see mostly sunny skies dominate the landscape due to a high pressure system over our area.  However, as it slides offshore, flow will come out of the southwest providing for an increase in moisture and retention of heat, so this is where the humidity increase will come from.  Generally speaking, 60-65° starts to feel sticky (tomorrow), 65-69° is uncomfortable (Monday), and 70°+ is oppressive (Tuesday), so we'll be going through all of these stages over the next few days (with highs in the 90's).

GFS MOS Data with dew points highlighted in a red box

    So when will we see rain again?  A June that was 5.65" above normal in rainfall (in Philadelphia) quelled drought concerns, but a below-average July in precipitation has made it seem pretty dry recently (almost in the lowest drought category per The National Drought Mitigation Center).  However, it appears that we could see a showery and stormy end to the week due to an approaching cold front.  Tuesday and Wednesday will see the slight threat for an isolated shower or storm, but those days will more likely than not remain dry, with partly sunny conditions.  This does not quite look to be the case for Thursday and Friday though.

   A low pressure system will move across the Great Lakes/Upper Midwest region on Thursday, and its associated cold front will affect our region to end the work week.  The period from Thursday morning to Friday evening has the highest precipitation threat for the week, with the chance for showers, downpours, and thunderstorms, with breaks of sunshine between.  Below is the GFS model run for this morning displaying Thursday's precipitation to give an idea of the rainfall across the area as the cold front approaches,  As always with being this far out, if this front speeds up, we could be looking at some rain sneaking its way into your Wednesday PM.

12Z GFS model run showing Thursday at 2pm (Image courtesy of Tropical Tidbits)