Date: 201308
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Weather elements / visibility: Thunderstorm
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Communication Breakdown; Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Contributing factors: Weather; Procedure
Primary problem: Procedure

Narrative: Enroute; surrounded by convective conditions and following many prior deviations around large thunderstorms; we had a cell appear on the radar approximately 17 miles directly ahead on our course. We asked ATC for '10 right' to avoid the cell ahead. ATC's response was to standby. Cell depiction then turned to lightning bolt symbol. About 12 miles from cell; we contacted ATC again requesting 10 right for weather ahead. The ATC response again was to standby. Five prior to cell; ATC contacted us and asked what we wanted. We advised we were turning right to avoid cell ahead. ATC Controller then told us we were violating our clearance and wanted to know what emergency we were declaring. We advised we were turning for weather and ATC Controller then launched into a dialogue about how he was too busy directing traffic to deal with us and how we needed to declare an emergency if we wanted to deviate from his clearance; etc. Basically; instead of providing assistance and doing his job; the Controller appeared to be seeking conflict with us. I do not believe any violation of regulations occurred. This report is being provided based upon the recommendation from the Company ATC Specialist.


Second narrative: We were enroute and I was the pilot flying. We were flying in an area with scattered very large air mass thunderstorms. Some storms exceeded over 50;000 FT and were still building. We had been deviating for the last 200 NM over the front range of the Rockies. We could see thunderstorms rapidly building around and in front of us. Several times during the flight we were IMC and were flying around embedded thunderstorms. After navigating through a very large line of thunderstorms; we were able to proceed direct [to] an intersection on the RNAV arrival. Many aircraft were deviating around the storms too. We had been at FL360 and ATC descended us to FL320. We entered a layer and became IMC. We were approaching a thunderstorm cell [that] was building 20 NM in front of us. I asked the Captain; who was the pilot not flying; what he thought and we both agreed we should deviate around the storm to the north because there was large storms to the south. The Captain made three attempts to contact Center. The thunderstorm was rapidly building and was now above our altitude. We estimated the top of this storm to be above 42;000 FT. We received a lightning symbol over the storm and a magenta core had developed indicating a severe storm. The Captain attempted to contact Center again and received no response. I made the decision to deviate 10 degrees to the north. The thunderstorm had built so rapidly that I had to turn further 20 degrees to avoid contact with the storm. The Captain finally was able to establish contact with Center to tell him we were deviating to the north. The Controller became very irate and asked us if we were declaring an emergency. We told him no. Center angrily told us we had 'no right to deviate' from our clearance and demanded us to declare an emergency. The Captain and I were perplexed at the reaction of this Air Traffic Controller. The Center Controller began his tirade to us that he was busy coordinating a RJ and another 737 around thunderstorms and he was 'doing his job' and demanded that we declare an emergency. The Captain professionally told the Center Controller that he was exercising his authority for the safety of the flight to deviate around this severe thunderstorm and we were now proceeding direct to cleared intersection. We only deviated five NM to the north of this thunderstorm and the only closest aircraft was another carrier's flight 20 NM behind us at our altitude and they needed to deviate too. After landing; the Captain contacted Dispatch and spoke with the Supervisor about the incident and then spoke with a Company ATC Representative. The Company ATC Representative told us we did not violate any FAR's and recommended we both submit a report.


Synopsis: A B737-800 crew diverted around a fast building; severe thunderstorm without clearance because ATC failed to answer their request in a timely manner but the Controller objected to their action because no emergency was declared.