This is a common complaint and, luckily has a simple solution. I'll start with the solution and (if you're interested in the "why" of it) conclude with the cause.
First (solution)... your oven igniter has failed.
Second (cause)... Your oven utilizes a "glow" type igniter. In order for it to glow, electricity is applied and the current flowing through it causes it to get very, very hot. This electrical current is monitored by a device called a safety valve. This valve is programmed to open up main gas flow to the burner manifold after the igniter "flows" 2.6 to 3.2 amps.
Igniters are tricky little guys. Unlike a light bulb (which is either good or it's bad) igniters get "weak". So what happens is the igniter gets to 2.5, then to 2.59 then to 2.62, then back to 2.5 amps. It goes up and down. But the 2.62 amp "flow" was enough to open main gas, but not enough to ignite it. So there it goes... up and down. All the while the main gas is opening and closing, but not being ignited. This gas accumulates. Then finally, the igniter reaches it's ignition temperature.
That's when you get the explosion. The "whoosh".
It's not that difficult to replace the igniter. Yours is a part #WB2X9998 and can be purchased at a local appliance parts retailer or ordered online
PULL THE OVEN OUT SLIGHTLY, REACH BEHIND IT AND UNPLUG IT!!!
1.) 1/4" socket or nut driver
2.) Flat or Phillips screwdriver
4.) Wire cutters
5.) Wire strippers
Remove the racks and then remove the "floor" panel of the oven. Then remove the diverter panel/burner baffle. Basically, your goal here is to disassemble the bottom of the oven. You may need to pull the lower drawer out.
After you have gained access to the igniter...you'll see that it's attached to the main manifold with two 1/4" screws (take note of its' position and how it's mounted to the manifold, the new one has to be mounted exactly the same). Word to the wise, here... use a little bit of liquid dish soap on the threads BEFORE trying to un-screw these. This will lubricate the threads and keep them from stripping. If you don't heed this warning and they strip? You'll have to grind them off in order to get the igniter removed.
Wire cutter time... snip the 2 white wires about 3" from the base of the old igniter. Wire stripper time... strip those 2 wires about a 1/2".
Now the old igniter is out. Pull out your new igniter. Cut any extraneous stuff off the END of the wires then strip them about a 1/2". Now mount the new igniter to the manifold (where the old one came from). Now take one wire (doesn't matter which one) from the new igniter and twist it to one of the wires you cut and stripped while removing the old igniter. Then use one of the ceramic wire nuts (included with your new igniter) and twist it on the exposed wires clock wise. Make sure there is NO WIRE EXPOSED after doing this. If there is, remove the wire nut and cut a small amount of you twisted wire pair off.
ALL OF THE EXPOSED WIRE SHALL BE INSIDE THE WIRE NUTS.
Do the same thing for the other wire. Now tuck all of the extra wire away. At this point, you're ready to test your handywork! Set it to bake and watch her light up (without the explosion tis time)!
All that's left to do now is rebuild the lower oven, grab a coolada and get some cookie dough. I'll be over at 6:00 for snacks :-)