MDT HAS ALT EXCURSION DUE STRONG WIND SHEAR; SEVERE TURB AND SEVERE DOWNDRAFTS.

Narrative

I WAS THE FO ON A FLT FROM ST. LOUIS; MO; TO LOUISVILLE; KY; WITH A SCHEDULED DEP TIME OF XA15 LCL. AT DEP TIME; THERE WERE SCATTERED STORMS MOVING THROUGH THE AREA. WE WERE HOLDING SHORT OF RWY 12R AT INTXN M; WHEN THE TWR CTLR TOLD US THAT THE WIND WAS NOW FROM 330 DEGS AT 16 KTS AND ISSUED TAXI INSTRUCTIONS FOR US TO USE RWY 30L INSTEAD OF 12R. AT THIS TIME THE CAPT TOLD ME TO TELL ATC THAT WE COULD STILL ACCEPT A TKOF AT RWY 12R AT INTXN M. AT THIS TIME I PROMPTLY TOLD THE CAPT THAT WE 'COULD NOT' ACCEPT THIS BECAUSE WE HAVE A 10 KT TAILWIND COMPONENT LIMITATION ON THE MDT AND THE WINDS WERE FROM 330 DEGS AT 16 KTS. AT THIS TIME THE CAPT TOLD ATC THAT WE 'COULD' ACCEPT THE TKOF AND ATC ISSUED US A 'POS AND HOLD' ON RWY 12R AT INTXN M; AND THEN A TKOF CLRNC WITH A TURN TO 180 DEGS. ONCE AGAIN; I TOLD THE CAPT THAT WE COULD NOT ACCEPT THIS TKOF AND HE COMPLETELY IGNORED ME AND STARTED THE TKOF ROLL. I FELT THAT IT WAS MORE DANGEROUS TO WRESTLE WITH THE CAPT OVER CTL OF THE ACFT; SO I ALLOWED THE TKOF TO CONTINUE. THE TKOF WAS NORMAL AND WE SWITCHED TO DEP AND WERE ASSIGNED A CLB TO 5000 FT. WHILE ON A HDG OF 180 DEGS AND LEVEL AT 5000 FT; WE ENTERED AN AREA OF STRONG WIND SHEAR AND SEVERE TURB. WE WERE UNABLE TO MAINTAIN OUR ALT OF 5000 FT DUE TO THE SEVERE DOWNDRAFTS. THE ACFT DSNDED TO 4200 FT. THE LOSS OF ALT WAS TOTALLY UNAVOIDABLE; THE AIRSPD WAS DECAYING AT A RAPID RATE AND THE ACFT WOULD NOT MAINTAIN ALT WITHOUT STALLING. SO THE CAPT DID THE ONLY THING HE COULD DO AND THAT WAS TO LOWER THE PITCH ATTITUDE TO INCREASE AIRSPD AND THE ACFT DSNDED TO 4200 FT.